Complete residual compressive stress straightening device and technology for crankshaft

Abstract

The invention provides a complete residual compressive stress straightening device and technology for a crankshaft. The device and technology solve the technical problems that after an existing crankshaft finished product is accurately ground, a straightening technology is required, cold straightening is not allowed, press rectification cannot be conducted on a press machine, either, and therefore tensile stresses can be formed on the surfaces, opposite to loading force, of the circular bead positions at the two ends easily, the original fatigue strength of the crankshaft is lowered, and cracking can happen easily in the work running process of an engine. The complete residual compressive stress straightening device is provided with an upper rolling swing arm and a lower rolling swing arm. One end of the upper rolling swing arm and one end of the lower rolling swing arm are hinged together through an open pressurization device, and the other end of the upper rolling swing arm is provided with an upper rolling part. The upper rolling part comprises an upper rolling wheel, and the upper rolling wheel is connected with the upper rolling part in a rotating mode. The other end of the lower rolling swing arm is provided with a lower support rolling part. The lower support rolling part comprises lower support roller wheels, and the lower support roller wheels are connected with the lower support rolling part in a rotating mode. The complete residual compressive stress straightening device and technology can be widely applied to correction happening when radial run-out of the crankshaft is out of tolerance.

Description

technical field [0001] The invention relates to a crankshaft straightening device and method, in particular to a crankshaft complete residual compressive stress straightening device and method. Background technique [0002] We know that after the crankshaft is cast or forged to form a blank, it needs to be machined. The basic process of machining is rough machining, semi-finishing and finishing, and finally forms a finished product. The finishing process is usually done on a grinding machine. After finishing grinding, in order to ensure the good working performance of the engine, the runout of the intermediate shaft diameter of the crankshaft shall not exceed 0.15mm. However, due to the stress release during the processing, After the crankshaft is finely ground, about 20% of the intermediate shaft diameter runout will be out of tolerance. If it is not straightened, it will become a waste product. [0003] After the existing finished crankshaft is finely ground, it must be s...

AI Technical Summary

Problems solved by technology

[0004] The present invention aims to solve the problem that the finished crankshaft is not allowed to be cold straightened after fine grinding, because the forced cold straightening method is used to press and straighten the crankshaft. Loading, it is easy to form tensile stress on the surface opposite to the loading force at the rounded corners at both ends, which reduces the original fatigue strength of the crankshaft by 10%, and it is easy to cause fracture during the working process of the engine; at the same time, thermal alignment cannot be performed. It will cause oxidation on the surface of the finished crankshaft, and the hardened layer and compressive stress formed at the rounded corners by the previous heat treatment process such as quenching and nitriding will also be destroyed. To provide a finished crankshaft after fine grinding, the finished crankshaft There is no need for cold straightening, no forced cold straightening method, no tensile stress will be formed on the surface opposite to the loading force at the rounded corners at both ends, the original fatigue strength of the crankshaft will not be reduced, and it is not easy to appear during the operation of the engine fracture, and does not require thermal straightening at the same time, it will not cause oxidation on the finished surface of the finished crankshaft, and the hardened layer and compressive stress formed at the fillet by the pre-heat treatment process of the finished crankshaft, such as quenching and nitriding, will not be damaged. Measurement Simple, simple process parameters, convenient operation, a crankshaft completely uniform residual compressive stress straightening device and method that can use constant rolling force to form residual compressive stress on the crankshaft after fine grinding

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