Die bending and forging finishing process of crank blank of low-speed diesel engine

Abstract

The invention relates to a die bending and forging finishing process of a crank blank of a low-speed diesel engine, wherein a production method is as follows: an upset crank blank is obtained through the processes of steelmaking, upsetting of a steel ingot and drawing, and then the upset crank blank is molded into a standard crank blank by the press function of a finishing punch and a backward extrusion function of an arc molding block of a finishing die through the finishing punch on an oil press of 8000T. In comparison with a traditional method, the process in the invention is capable of guaranteeing full fibers of a crank pin and a crank arm, and getting rid of secondary forging in the die forging process simultaneously, thereby achieving a purpose of finishing the forging by one time, decreasing the flowing time in the crank production process, preventing from folding a crank opening, disposing oxide skin accumulation of the opening, decreasing machining allowance of forgings, improving the internal quality of the crank forgings, the qualification rate of forging flaw detection and the material utilization rate.

Description

technical field [0001] The invention relates to a roll bending hot die forging forming method for forging a crank of a low-speed diesel engine by using a special forming die. Background technique [0002] The crank is an important part of the crankshaft. According to the crankshaft design of the semi-combined low-speed diesel engine, the opening gear of the low-speed diesel engine crank must be forged with the crank arm of the crank, so that the fiber of the tube opening gear and the crank arm is continuous; this requires that the shape of the low-speed diesel engine crank cannot be opened through previous machining. Turn the method into shape. The low-speed diesel engine crank produced by the traditional method is opened by machining, and the quality is difficult to meet the complex working conditions of the crank. [0003] At present, the main method for producing low-speed diesel engine cranks is bending forging, followed by block forging, bending forging, and die forgi...

AI Technical Summary

Problems solved by technology

[0004] The die forging method is the technology disclosed in the Applicant's "Manufacturing Process and Device for Crankshaft Crank Throw of Large Diesel Engine for Marine Use" (Chinese Patent 200410060819.3) and "Manufacturing Device for Crank Throw of Crankshaft of Large Diesel Engine for Marine Use" (Chinese Patent 200420076782.9), and it is mainly aimed at S60MC And the patented technology of crank bending and forging for models below S60MC, the basic idea is to pass the block crank blank through the closed cavity, and use the punching plate to form the middle opening; the formed crank has opening folding and oxide scale accumulation And so on, these problems affect the finishing size of the crank after the final molding, and this technology has the disadvantages of different models, the mold cannot be shared, and the cost of tooling is very high.

[0005] The bending forging method is a process of using the device disclosed in the applicant's "Adjustable Device for Bending and Forging Large Diesel Engine Crankshaft Forgings of Marine Diesel Engines" (Chinese Patent 200620095181.1), and using this device to bend the two crank arms of the crank to a certain degree The required tooling is mainly for the crank bending and forging process of the S60MC machine and models below the S60MC machine. This technology still does not solve the problems of open gear folding and scale accumulation of the formed crank, and it cannot cover it comprehensively. The current mainstream models of low-speed diesel engine cranks (S90MC and models below S90MC)

[0006] The crank design of the new low-speed diesel engine requires integral forging of the opening gear and the crank arm. In the forming process, how to position and align the formed crank arm is relatively uniform, and the opening gear size meets the design requirements, which is also very difficult.

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