SU1286312A1 - Method of straightening crankshafts - Google Patents

Abstract

The invention relates to the repair and restoration of worn parts and allows the crankshaft to be straightened, providing an increase in the productivity of the process and an improvement in the quality of the products due to the fact that the shaft is suspended by its end flange in a vertical position. The shaft neck is heated on the side of its bulge to 860-930 ° C, and on the side of the concavity - up to 550-650 ° C. Cooled with water to 40-70 ° C areas of the necks, which were heated to 860-930 ° C. The remaining parts of the necks are cooled in air. Thereafter, the entire shaft is uniformly heated to 860-930 ° C and cooled to room temperature. Due to the fact that there is no mechanical effect on the shaft, the strength of the shafts after heat treatment is not reduced. -1 h. apt.

Description

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The invention relates to the repair and restoration of worn parts, specifically to methods of editing remanufactured parts, mainly crankshafts, and may find application in mechanical engineering in the manufacture of such parts.

The aim of the invention is to improve the performance of the dressing process and improve the quality of products.

The proposed method of drying is as follows.

The shaft to be fixed is suspended in a vertical position by its end flange, the shaft necks are heated on the side of its bulge to 860–930 ° C, and on the opposite side, i.e. from the side of the shaft concavity, at the same time the necks are heated to 550-650 ° С, then they are cooled with water to 40-70 ° С only those portions of the necks that have been heated to 860-930 ° С, the remaining portions of these necks are cooled after heating air, the entire shaft is uniformly heated to 860-930 ° C and cooled to room temperature. The cycle of heating and cooling of these areas of the necks is repeated until the beating (deflection) at the crankshaft becomes zero. In this case, the heating of the necks can be carried out by high-frequency currents.

The proposed method of straightening crankshafts in comparison with the known ones has the following, and advantages: there is no mechanical impact on the part, therefore, the strength of the crankshafts does not decrease after processing; after straightening, the crankshaft does not change its shape due to reheating of the released necks to quenching temperatures and cooling with water; while correcting the curvature of the shaft, the wear resistance (hardness, strength) of its released necks is increased; the necks of straightened crankshafts have no surface defects (burns, metal erosion, etc.).

Example. The engine crankshaft of steel 45G, received for repair, was edited by the proposed method. The above crankshaft was edited by performing the following operations in the following sequence. The crankshaft was installed in the centers of adaptation and its deflection (beating) was measured by the indicator of the average

the neck. Before straightening, the crankshaft beating was 1.41 mm. Then, the shaft was removed from the tool and hung vertically, fixing it by a flange, in a machine for quenching crankshafts. After that, two crank pins, located on both sides of the middle main neck, were installed in the inductors so that the gap between the inductor wall and the neck was 3-4 mm from the convexity of the crankshaft, and from 8 to 12 mm from the concavity side. Included generator HDTV and heated these necks at the crankshaft. Heating was controlled by heat indicators and pyrometer. When reaching the convexity of the shaft temperature at

such necks equal to 860–930 ° C (quenching temperatures), turned off the heating and instantly turned on the water supply to the surfaces heated to quenching temperatures and cooled these necks to 40–70 ° C with water.

Claims (2)

1. A method of straightening crankshafts, including local heating of the shaft and subsequent cooling in the place of its greatest deflection, characterized in that, in order to increase the productivity of the straightening process and improve the quality of products, the shaft is suspended in a vertical position beyond its end flange, to local heating on the side of its bulge up to 860–930 ° C, and on the side of the concavity up to 550–650 ° C, water is cooled to 40–70 ° C by neck sections that have been heated to 860–930 ° C; cooled in air, after which the shaft is re-uniformly heated to 860-930 ° C, and cooled to room temperature. 2. A method according to claim 1, characterized in that the heating of the necks is performed by high-frequency currents.