Even after applying force to eliminate visible bending deviations, residual stress distribution may still remain uneven within lamp posts. In certain areas, residual stress balances with external forces. When external conditions change (e.g., temperature fluctuations or prolonged loads), stress release can cause the pole to bend again—a phenomenon known as "rebound." Therefore, another key to improving straightening accuracy lies in controlling internal stress to ensure the pole maintains a stable straightened state post-correction.
Internal stress control in straightening machines is primarily achieved through two approaches: staged loading/unloading and aging treatment assistance. Staged loading involves applying incremental correction forces in phases to gradually expand plastic deformation within materials, preventing stress concentration caused by large one-time deformations. Staged unloading refers to systematically removing external forces after reaching target deformation levels, ensuring uniform distribution of residual stresses rather than localized accumulation. Some straightening machines integrate low-temperature aging or vibration aging functions, utilizing subtle temperature variations or mechanical vibrations to promote internal stress relaxation and further stabilize rod geometry. This dual control mechanism targeting both "explicit deviations" and "implicit stresses" ensures long-term linear accuracy stability, eliminating transient "correction artifacts."
