Recently, the Mining Machinery Plant introduced a round bell kiln for stronger branding and higher quality of Hadfield steel products. The round bell kiln is a special heat treatment device with rolling and breaking walls and upper and lower bushing round castings, with the advantages of precise temperature control, small casting heat treatment deformation and short water entry time. The bell kiln, which was installed on May 18, has been successfully operated and achieved initial results after over 40 days of commissioning and heat treatment process adjustment.

In the past, workers needed to manually hang fence for the casting quenching process, which caused an uncertainty in personnel reaction time that seriously affected the time requirements of the process.

Therefore, the machinery plant designed and manufactured the quenching steel fork to cancel the lifting rail operation, reducing the time it takes for the work piece to enter the water by 40 seconds and effectively guaranteeing the quenching quality.

The tracking shows that the deformation of the work piece after quenching is controlled within a range of 5 to 8 mm, and the machining process can be started without profile adjustment. At the same time, the cross-bar operation makes the stress of the quenching fence reasonable, reducing the weight by 50%, and saving 5.5 tons of steel used in the quenching fence every month.

Due to the good sealing performance of the bell kiln, the oxide skin thickness of the castings after quenching is less than 1 mm, while that of the other two electric kilns in the mechanical plant is 2 to 3 mm. A thinner oxide scale means a thicker wall on the casting, which is equivalent to an increase of 4 mm in the wall thickness of the wear-resistant casting. Taking the rolling and breaking walls of two mines as an example, the initial wall thickness is 110 mm, and the wall thickness after use is 40 mm. Increasing wall thickness by 4 mm is equivalent to prolonging service life by 5%.

Relying on the control accuracy and reasonable production organization of the round kiln, the machinery plant has made the quality of Hadfield steel products fully meet the requirements of the 2009 national standard and Metso mining machine, further enhancing its “quality control” capability and greatly improving the stability of spare parts. Starting with the two-wall castings, the machinery plant will realize the industrial upgrading to produce high-end wear-resistant castings and export products.