Release time：2020-01-16 18:44 Browse：
To ensure the perpendicularity of an elongated screw after straightening, a systematic correction and inspection process must be followed, along with proper techniques and tools. Below are the detailed steps and considerations:
Inspect the threads and surface: Ensure the screw has no bends, damaged threads, or rust.
Select a reference surface: Use a flat and perpendicular reference surface (e.g., machine table or calibrated plate).
Manual straightening (for minor bends):
Place the screw on a flat surface and gently tap the raised areas with a rubber mallet.
Check perpendicularity with a square or combination square at intervals (e.g., every 100mm).
Mechanical pressing (for severe bends):
Use a hydraulic press or arbor press with V-blocks to support the screw and apply gradual pressure.
Note: Use soft metal (e.g., copper) to protect the threads.
Specialized tools:
Dial indicator: Secure the screw in a lathe or measuring stand, rotate it, and measure radial runout (target: <0.1mm/m).
Laser collimator (for extra-long screws >1m): Ensures overall straightness.
Square gauge method:
Place the screw vertically on a reference surface.
Use a square to check gaps; measure deviation with a feeler gauge (target: ≤0.05mm/m).
CMM (for high precision):
Perform 3D scanning to generate a perpendicularity report (accuracy up to ±0.01mm).
Straighten in sections: Avoid overcorrecting one area.
Temperature control: Avoid thermal expansion effects.
Prevent secondary damage: Do not hammer threads directly.
Storage: Hang vertically or lay flat on a well-supported rack.
Material selection: For critical applications, use high-strength alloy steel or stainless steel.
For high-precision uses (e.g., aerospace), professional metrology verification is recommended.
