Preparing method of G20Cr2Ni4 bearing steel large-scale special-shaped cross section annular blank

Abstract

The invention discloses a preparing method of a G20Cr2Ni4 bearing steel large-scale special-shaped cross section annular blank. The preparing method comprises the steps that a G20Cr2Ni4 alloy bar is heated to be 1180+ / -20 DEG C in a certain heating mode, and is then subjected to upsetting, punching and rolling to become a rectangular cross section annular blank; then, the rectangular cross section annular blank is expanded into a primary special-shaped cross section annular blank at the pressure of 24 to 28MN; next, the primary special-shaped cross section annular blank is expanded into a secondary special-shaped cross section annular blank at the pressure of 22 to 26MN; then, the upper end of the secondary special-shaped cross section annular blank higher than a loose tooling is subjected to free upsetting to be flush with the loose tooling at the pressure of 10 to 14MN, and the final special-shaped cross section annular blank is obtained. The method has the advantages that the forming pressure required by the blank manufacturing can be effectively reduced, meanwhile, the flow direction of process excess materials can be effectively controlled, and the forming dimension of an intermediate blank is ensured. The method is applicable to the preparation of the intermediate blank of a large-scale special-shaped cross section annular blank element.

Description

technical field [0001] The invention relates to a blank-making method of a ring forging, in particular to a method for preparing a large ring blank of G20Cr2Ni4 bearing steel with special-shaped cross-section. Background technique [0002] The ring rolling technology of ring forgings is an advanced forging technology, which is becoming more and more mature, and the size of ring forgings is getting bigger and bigger, and the shape is becoming more and more complex. In order to obtain a ring forging with qualified shape and size and excellent performance, the key is to make a reasonable intermediate blank. [0003] The Chinese invention patent specification CN101020284A (application number: 200710077667.1) published on August 22, 2007 discloses a method for making a high-temperature alloy large-scale special-shaped cross-section ring blank. The blank-making process adopted in this patent is: upsetting and punching on a forging press , rolled into a rectangular ring blank on a...

AI Technical Summary

Problems solved by technology

This process is used to make blanks. After the mold is closed, the mold is completely closed. When producing large and heavy rings, such as large-scale special-shaped cross-section ring blanks made of G20Cr2Ni4 bearing steel, the weight of the forging is relatively large, reaching 1.5 tons. To 2 tons or even higher, the maximum value of the instantaneous pressure of mold closing has reached more than 100MN (equivalent to a pressure of 10,000 tons), but there are very few domestic manufacturers with tens of thousands of tons of forging equipment, and most manufacturers are unable to produce such large and heavy-duty forging equipment. Shaped ring forgings

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