Improving the efficiency of surface-thermal hardening of machine parts in conditions of combination of processing technologies, integrated on a single machine tool base

OBRABOTKAMETALLOV Vol. 23 No. 3 2021 technology Ta b l e 2 The initial data on the allowances and operating dimensions calculation for the processing of the hardened surface Operation No. Draft The operation and technical requirements for its implementation 15 Turning the surface 1 . Ellipticity within tolerance on diameter D 1 which is to be determined 20 Surface 1 hardening by HFC at the depth A T . The hardness of the hardened surface is 700…800 HV . Increase in D 1 diameter caused by the 8 ... 10 µm swelling per each millimeter of the hardened layer thickness. 25 Finish grinding of the surface 1 Fig. 9. Diagram of workpiece HFC har- dening by the standard technology determining the change in the depth of the hardened layer is the constancy of the gap between the inductor and the heated surface. According to the factory technology, the part is based on the surface 2 on a rigid mandrel installed in the centers. Quenching is carried out in a continuous-sequential way using an annular inductor D I +0.74 ( D = 52 H14 ) (Fig. 9). The technological gap between the inductor and the part is 3 mm. In this case, the change in the gap is due to the displacement of the center of rotation of the part, which is determined by the error of the shape of the inductor and the error of the part positioning. To obtain a circumferentially symmetrical layer, the rotation of the part is used. According to experimental data, it was found that for these conditions of HFC quenching, provided that the inductor is aligned relative to the axis of the centers – δ Т = 0.1 mm. In this case, we have δ t = 0.4 – 0.1 = 0.3 mm. 2. We determine the permissible value of the total spatial devia- tion ∑ δ еi , taking into account the operational tolerances for mis- alignment δ еi , the sequence of operations, the methods of basing and positioning. According to the data of [27, 28, 65], for carbon steels, the in- crease in the specific volume of the quenched surface is 0.5 %. During surface quenching, when the directions of free expansion