Research On Influence Factors Of Tri-ethylamine Cold Box Core-making Process

Tri-ethylamine Cold Box Core-making Process, with the features of more efficiency, energy saving, good casting surface quality, accurate dimension, good core collapsibility, has been widely used in automobiles, internal combustion engines, tractor, engineering machinery, rolling stock, brake pump. However, the high usage amount of resin, low performance and bad storage of sand core lead to the high scrap rate in production process of some Foundry Enterprise. Therefore, further studies on these problems can provide technical support for optimization of Tri-ethylamine Cold Box Core-making Process, enhancing sand core performance and reducing production cost, which have important realistic significance.In this paper, combining the production practice of No.1 Foundry Plant, Dongfeng motor Co., Ltd (hereinafter called: No.1 Foundry Plant), reasons for the high usage amount of resin and low efficiency of core-making were analyzed. Furthermore, effects of process conditions for sand core performance of Tri-ethylamine Cold Box based on actual production were studied. Finally, several improvement measures of ISOCURE of No.1 Foundry Plant were proposed, and the results achieved are as follows.Through analyzing quality of raw materials and production process of Tri-ethylamine Cold Box Core-making of No.1 Foundry Plant, high water content of the raw sand and the compressed air is identified as the main reason for high usage amount of resin.The effect of the amount of added resin on sand core performance was studied. The results showed that the initial strength and the 24h final strength of sand core increased with the increase of amount of addition of resin, the gas evolution indicate the same variation tendency. When the amount of added resin is 1.8%, he 24h final strength reach the maximum at the ratio of two components is 50:50, and the initial strength reaches its maximum at the ratio of 55:45. It is also can be seen that the tensile strength of sand core has good stability when the ratio is between 50:50 and 55:45.And then, research of water-based paint, environmental humidity and temperature on strength and fracture of sand core were also explored. The results showed that the water-based paint made the 24h final strength decrease significantly, but the decline rate decreased with the increase amount of added resin; the strength of core painted during storage time 1-6h was lower than that of immediate painted core and painted after storage 24h. In the environment of room temperature and high humidity, the core strength decreased significantly due to high humidity with the extension of storage time. In the environment of 40℃and RH100%, the sand core reaches its maximum strength within 5h, and then the strength declined rapidly with the extension of storage time. The resin binding bridge showed cohesive-fracture-dominated compound fracture in the environment of room temperature and low humidity, While, the resin binding bridge showed the adhesive fracture because of moisture-induced cracks in high humidity environment.Based on these, several improvements for the raw water content, sand mulling, compressed air dryer, dip coating and heating, process and tooling parameters and sand core storage have been proposed to reduce the usage amount of resin and increase efficiency of core-making.