Explain heat treatment and precision of machining process.

Content 1: Heat treatment in machining process of parts.

Heat treatment in machining process of parts can be divided into two kinds: preliminary heat treatment and final heat treatment.

Preliminary heat treatment: its purpose is to improve mechanical properties, eliminate internal stress, in order to prepare for the final heat treatment, generally including annealing, normalizing, tempering and aging treatment and other processes. Preparatory heat treatment is usually carried out after rough machining.

Final heat treatment: its purpose is to increase the hardness and wear resistance of parts, including quenching, carburizing, nitriding and other processes, generally after semi-finishing, finishing before.

Content two: machining accuracy.

Machining accuracy is mainly reflected in the following aspects, for dimensional accuracy, geometric accuracy and mutual position accuracy, which includes roundness, straightness and flatness, mutual position accuracy including parallelism, verticality and coaxiality.

Content three: what are the methods to obtain machining accuracy?

1. Dimensional accuracy: there are mainly trial cutting method, adjustment method, sizing method and automatic control method.

2, geometric shape accuracy: there are mainly trajectory method, forming method and development method and other methods.

3, mutual position accuracy: there are mainly direct installation method, alignment installation method and fixture installation method.

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