Continuous fuel‑atmosphere‑protected carburizing, quenching, cleaning, and tempering heat‑treatment production line for self‑tapping screws

This heat‑treatment production line overcomes the traditional challenges of manual handling and associated losses in decentralized heat‑treatment processes. By employing a fuel‑fired, controllable atmosphere as the core heating and carburizing medium, it reduces overall energy consumption compared with conventional electric‑heated carburizing lines. Coupled with a high‑precision oxygen‑probe‑based carbon‑potential closed‑loop control system, the furnace’s carbon potential is maintained with an accuracy of ±0.05%, fundamentally eliminating common defects such as uneven carburized layers, surface oxidation and decarburization, and excessive hardness variation—issues frequently encountered with small workpieces. Workpieces processed on this line exhibit uniformly consistent carburized layer depths, with excellent matching between core toughness and surface hardness; this ensures no brittle fracture during tightening while also guaranteeing long‑term wear resistance of the threaded surfaces and preventing thread stripping. The entire line operates continuously and automatically through the full process—from carburizing and quenching to low‑temperature tempering—significantly boosting annual throughput while requiring only minimal human supervision.