Abstract:         Regarding the assembly side-bending problem caused by the inconsistent center distance between the two chain plates of the large pitch stacker conveyor due to thermal treatment distortion, this paper systematically studied the influence law of the thermal treatment process temperature on the change rate of the center distance of the 40Cr chain plates. Taking the chain plates processed from hot-rolled flat steel and hot-rolled medium plates as the research objects, multiple groups of quenching tests were conducted within the temperature range of 800–860 ℃. The results showed that for the same batch of materials, the change rate of the center distance of the chain plates and the quenching temperature had a good approximate linear relationship within the test range, and the size sensitivity of the flat steel chain plates was higher than that of the medium plate chain plates. Based on this rule, a technical path was proposed to achieve the matching of the center distance change rate by precisely regulating the thermal treatment process temperature of different chain plates. Practical application showed that this method could stably control the assembly error within 0.03%, completely solving the side-bending problem of the chain, and the one-time acceptance rate of the product increased to 99.2%. The mechanical performance verification indicated that the breaking load of the chain under the optimized process still met the standard requirements. This research provided an effective engineering solution for the coordinated control of thermal treatment deformation of heterogeneous component assemblies.