High-strength non-cracking antiwear precise hollow axle and its making technology

Abstract

A high-strength antiwear precise hollow shaft without breaking is made up of low-alloy cast steel containing C, Si, Mn, Cr, Ni, Mo, V and Fe through smelting, casting, annealing, coarse turning, modifying, fine turning, grinding, drilling and reaming. Its advantages include high strength, toughness and hardness, no defects and stress, high accuracy, long service life and low cost.

Description

technical field [0001] The invention relates to a precision hollow shaft with high strength, wear resistance and no fracture, which is mainly used in industries such as mines, building materials, metallurgy, electric power and machinery. It is a variety of horizontal rotary mills (also known as tube mills) for grinding and refining various ore raw materials or their semi-finished products, such as: raw material mill (raw mill), clinker mill (cement mill), drying mill, coal mill, etc. Key components in grinding and other equipment. The invention also relates to a manufacturing process of a high-strength, wear-resistant and non-fracture precision hollow shaft. technical background [0002] In the field of prior art, whether it is an advanced center drive or a backward edge drive mill, whether it is a large-scale grinding and refining production with a large momentum rotation or a small-scale grinding and refining production with a small momentum rotat...

AI Technical Summary

Problems solved by technology

As everyone knows, after annealing ZG35 or ZG45 cast steel, while eliminating or reducing casting stress, improving machinability and weldability, its strength, hardness and wear resistance will be greatly reduced to those of A3 steel; In the processing process after normalizing or annealing, the large area of ​​the bearing pad surface and the R area is repaired without preheating and tempering. On the one hand, the deformation stress is sharply increased, and the hardness of the bearing pad surface is seriously uneven. ; On the other hand, give the user the illusion that the appearance is temporarily qualified or basically qualified

This is the fundamental reason why the hollow shaft was seriously unqualified when it was re-inspected after being placed for several months, and a few products also showed self-cracking or unstable operation, and the root cause of pull-out or breakage in less than 3 months

Coupled with the ubiquitous internal casting defects of cast steel blanks: porosity, sand inclusions, cracks, segregation, etc., and deformation caused by various internal stresses (such as casting residual stress, repair welding, processing stress, etc.), it will inevitably seriously affect Improve the manufacturing quality, mechanical strength and service life of the hollow shaft

When the hollow shaft is subjected to the impact of rotating load and the grinding heat above 180°C or the hot air at 450-550°C, deformation of various stresses will inevitably occur, which will affect the service life and even break immediately

In particular, ZG40Cr has poor castability when casting hollow shaft blanks, and cracks often occur during tempering, so it can only be used for casting small hollow shaft blanks

[0016] The service life of imported hollow shafts is generally 8 to 10 years, and the price is expensive, generally around 60,000 yuan / ton; currently, the service life of hollow shafts with the best quality in China is generally 3 to 5 years, and most of them are 1 to 2 years Between; there are also many hollow shafts that crack after being used for 1 to 2 months; resulting in frequent shutdown or maintenance, which seriously affects the production progress, product quality and economic benefits of the manufacturer. The scrap rate of hollow shafts in China is very high. Therefore, its price is also very expensive, generally around 25,000 yuan / ton to 30,000 yuan / ton

[0017] The hollow shaft has a short service life and high manufacturing and use costs. It has been a technical and economic problem that has been urgently needed to be solved for many years in domestic mining, building materials, metallurgy, electric power and other production industries and machinery manufacturing industries.