Overhead crane wheels is small but important part of overhead crane. The quality of the overhead crane wheels affects the overhead crane quality and operation. The heat treatment to the crane wheels can directly the quality of overhead cranes wheel. In today article, the basic knowledge on heat treatment for overhead crane wheels will be put in length for your reference.
Overhead crane wheel usually are produced from the ZG310-570 cast steel or steel with better quality. The small size overhead crane wheels can be made of forged steel but not below the 45th stainless steel. The bear crane wheels bearing heavy loads are made of alloy steel, such as ZG55CrMn, ZG50MnMo, etc. Alloy material are also used when it is required to reduce the diameter of the overhead crane wheels and eventually to lower the height of the overhead cranes.
In order to increase the load capacity and service life of crane wheel, the wheel tread must be heat treated. It is required that the medial surface of wheel hardness is 300-380HB, 20mm of hardened depth not less than 260HB, which can be achieved under the current technical conditions by using a variety of heat treatments.
It is required in regulation GB6067 –1985 that the crane wheels should be scrapped when the rim thickness wear up to 50% of the original thickness. In "Crane design manual", it points out that the crane wheel rim bears the lateral pressure of crane, with 70% - 80% of the crane wheels rubbing on the side of the track, which may result in the wearing of the flange and making the wheel scrapped.Therefore, the heat treatment of the crane wheel should include the rim profile, i.e., during power frequency quenching, if the heat induction coil is too narrow, the rim inside surface hardness will not able to meet requirements.It is required in regulation GB6067 –1985 when the wheel tread thickness wear up to 15% of the original thickness should be scrapped. In the manufacturing process, to keep the tread hardness is moderate (too high will severe wear of the rail) and wheel tread depth at the 20mm meet the requirements (too low will cause severe wear of the wheel), it is the certain difficult. According to years of experience, when the carbon content less than 0.5% of the cast steel or ordinary carbon steel material, on the surface of the wheel tread depth of hardened layer will not meet requirements.Some manufacturers due to capacity constraints or because of cost considerations, the wheels were used table flame quenching heat treatment method, this method has only 2-5mm of hardened depth and the surface is brittle, running process, the wheel tread cracking and hardening off, causing wheel scrap, this approach should not be adopted.