A method for preventing cracking of large steel castings

Abstract

The invention belongs to the field of casting technology, and particularly relates to a pre-cleaning method for preventing cracking of large steel castings with shaft holes. The sand boxes with more than 3 floors above the ground are raised 20-50mm as a whole, and shake out after 8-9 days; shakeout: artificial shakeout, sand shakeout time is 30-50min; riser cutting: cutting temperature is controlled at 200- 350°C, first cut the riser and subsidy on the flange of the outer ring of the casting, and then cut the riser and subsidy of the middle spindle hole of the casting. This application provides a pre-cleaning method for preventing cracking of large steel castings with shaft holes, which changes the pre-cleaning method and process in the prior art, provides a complete and effective pre-cleaning method, and strictly controls the cracking of each node. Parameter value range to reduce stress and prevent cracks.

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