Anti-cracking method for large steel casting

Abstract

The invention belongs to the technical field of casting, and particularly relates to an anti-cracking pre-cleaning method for a large steel casting provided with a shaft hole. The method comprises thefollowing step of knockout, wherein the casting is placed for 4-5 days after being poured, and after the casting is solidified, sand boxes in three or more layers upwards from the ground are integrally lifted by 20-50mm and placed for 8-9 days before shakeout; shakeout, wherein manual shakeout is performed for 30-50min; and riser cutting, wherein the cutting temperature is controlled to be 200-350 DEG C, a riser and a patch on an outer ring flange of the casting are cut firstly, and then a riser and a patch of the middle main shaft hole of the casting are cut. According to the anti-cracking pre-cleaning method for the large steel casting provided with the shaft hole, a pre-cleaning method and a pre-cleaning process in the prior art are changed, the complete and effective pre-cleaning method is provided, and the parameter value range of each joint is strictly controlled, so that stress is reduced, and cracks are prevented from being generated.

Description

technical field [0001] The invention belongs to the technical field of casting, in particular to a pre-cleaning method for preventing cracking of large steel castings with shaft holes. Background technique [0002] Large-scale steel castings with shaft holes are generally made of carbon steel, with a complex structure and a tonnage of 50 tons to 80 tons. It is difficult to cast. The outer ring structure of the steel castings includes an upper flange and a lower flange. The main shaft hole is about m, the outer ring and the main shaft hole are connected by two beams and a drive shaft hole, the drive shaft hole, the main shaft hole and the beam are interlaced, and the drive shaft hole and the outer ring form a large wall thickness difference , coupled with the particularity of its structure, the casting stress is mainly concentrated in this part, which can easily lead to cracking of the casting, and the cracks generated are usually irreparable penetrating cracks, and even dire...

AI Technical Summary

Problems solved by technology

[0002] Large-scale steel castings with shaft holes are generally made of carbon steel, with a complex structure and a tonnage of 50 tons to 80 tons. It is difficult to cast. The outer ring structure of the steel castings includes an upper flange and a lower flange. The main shaft hole is about m, the outer ring and the main shaft hole are connected by two beams and a drive shaft hole, the drive shaft hole, the main shaft hole and the beam are interlaced, and the drive shaft hole and the outer ring form a large wall thickness difference , coupled with the particularity of its structure, the casting stress is mainly concentrated in this part, which can easily lead to cracking of the casting, and the cracks produced are usually irreparable penetrating cracks, and even directly lead to the scrapping of the casting

[0003] Due to the large tonnage of the above-mentioned steel castings, the specific process of pre-cleaning in the prior art is: normal temperature boxing and sand shakeout, preheating, cutting and risking, and mass heat treatment; The operation of the cleaning process will cause large cracks at the junction of the drive shaft hole and the outer ring, and the crack length can reach 0.5m~2m. Such cracks are basically irreparable, and as the storage time increases, the cracks will continue to extend

Therefore, the pre-cleaning method in the prior art is not suitable for the production of large-scale rusted steel parts with shaft holes. Therefore, it is necessary to focus on the pre-cleaning method suitable for the production of large-scale steel castings with shaft holes to reduce casting stress and avoid cracks. produce