The inspection, certification, and testing methods of triangle rulers in drawing instruments, especially synthetic resin drawing triangle rulers, usually follow specific standards and processes to ensure the quality and accuracy of the products. The following is a detailed description of these methods:

1. Inspection items and standards
Appearance quality
Check the overall appearance of the triangle ruler, including whether the surface coating is intact, scratch-free, and free of obvious defects.
Length, width, and width difference
Measure the length of each side of the triangle ruler to ensure that it meets the design requirements and standard regulations.
Flatness deviation
Detect the flatness of the surface of the triangle ruler to ensure that no errors will occur during use.
Working edge straightness deviation
Evaluate whether the working edge of the triangle ruler (i.e. the edge used for drawing) remains in a straight state to ensure the accuracy of the measurement.
Angle deviation
For triangle rulers, especially right-angle triangle rulers, it is necessary to detect whether their angles (such as 30°-60°-90° or 45°-45°-90°) meet the specified requirements.
Division indication deviation
Check whether the scale on the triangle ruler is consistent with the standard to ensure the precision and accuracy of its scale.
Line length, width, and width difference
Measure the length and width of the scale lines on the triangle ruler and evaluate their consistency.
2. Inspection method
Appearance quality inspection
Use the visual inspection method, combined with a standard light source magnifying glass and other tools to carefully inspect the appearance of the triangle ruler.
Dimension measurement
Use high-precision measuring instruments (such as a grating ruler, vernier caliper, etc.) to measure the length and width of the triangle ruler.
Flatness and straightness detection
Use high-precision detection equipment such as optical flatness detector and straightness detector to detect the flatness and straightness of the triangle ruler.
Angle detection
Use a precision angle measuring instrument (such as a universal angle ruler, electronic angle measuring instrument, etc.) to detect the angle of the triangle ruler.
Division indication detection
Use a standard dividing plate or dividing instrument to compare and detect the scale on the triangle ruler.
3. Inspection standards and certification
Inspection standards
The inspection of drawing triangle rulers usually follows national or industry standards, such as QB/T 1474.2-2005 "Plotter ruler triangle ruler". These standards specify the classification, requirements, test methods, inspection rules and markings, packaging, transportation, storage, and other aspects of triangle rulers.
Certification
Triangle ruler products may need to be certified by a third-party certification body to ensure that they comply with relevant standards and regulatory requirements. The certification process usually includes product testing, factory audits, and other links, and the corresponding certification certificate is issued after the certification is passed.
IV. Precautions
Testing environment
The test should be carried out under stable environmental conditions to avoid the influence of environmental factors such as temperature and humidity on the test results.
Testing tool calibration
Ensure that the testing tools used are calibrated and within the validity period to ensure the accuracy of the test results.
Operating specifications
During the testing process, the test standards and instrument manuals should be strictly followed to avoid inaccurate test results due to operating errors.
In summary, the testing, inspection, and certification test methods of drawing instrument triangle rulers involve multiple aspects, including test items, test methods, test standards, and certification. Through strict testing and certification processes, it can be ensured that the quality and accuracy of triangle ruler products meet the requirements of relevant standards and regulations.