Processing technology of link arm and steering wheel of qt-600 nodular cast iron

Abstract

The invention discloses a QT-600 nodular cast iron connection arm and steering wheel processing technology successively comprising the steps: destressing annealing treatment of a casting piece; rough machining; normalizing treatment; finish machining; workpiece overall surface nitriding compound treatment; laser quenching treatment of circular bead parts of a workpiece; deformation detection; and 0.1 mm finish machining polishing adjustment. The technology improves the product stability and repeatability; the product is firstly overall nitrided, the circular bead positions are subjected to laser quenching treatment, the surface of the casting piece obtains high hardness, at the same time, the original hardness and smoothness of cast iron and reliable quality are ensured, the internal stress in the casting piece is eliminated, the gradually cracking tendency of the circular bead parts of the product is reduced, the hardness value of a laser quenched area of a connection arm and a steering seat is improved, and the contradiction between the hardness and the machining precision is solved, and due to not many laser quenching treatment parts, almost no distortion of the casting piece after laser quenching exists.

Description

technical field [0001] The invention relates to a heat treatment process for graphite cast iron workpieces, in particular to a process for processing link arms and steering wheels of QT-600 nodular cast iron. Background technique [0002] Mechanical parts are widely made of ductile iron. While they require a certain hardness on the surface, they also require to maintain the original hardness and toughness of the matrix. Due to the composition of cast iron, the inhomogeneity of the structure, the internal stress is large, and the deformation is irregular, even if it is tempered. The quality is also uneven. At present, the link arm and steering wheel of QT-600 ductile iron are processed by conventional heat treatment process. Often due to the high heat treatment hardness of the product, it is difficult to machine, resulting in difficult processing, low machining accuracy, and low heat treatment hardness. It will also cause the product to be easily cracked and damaged. If the ...

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Problems solved by technology

The quality is also uneven. At present, the link arm and steering wheel of QT-600 ductile iron are processed by conventional heat treatment process. Often due to the high heat treatment hardness of the product, it is difficult to machine, resulting in difficult processing, low machining accuracy, and low heat treatment hardness. It will also cause the product to be easily cracked and damaged. If the finishing process is completed and then heat treated, the problem of difficult processing and low hardness will be solved. However, due to the surface treatment of the product, the overall deformation will be serious, and it is still unusable. After treatment, internal stress still exists inside the product, which often leads to easy cracking and damage at the rounded corners of the product, poor product quality stability, and traditional heat treatment process will pollute the environment

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