# Design of riser for bridge bearing steel casting

Taking the steel damping bearing as the research object, because of the complex structure of the product, the calculation of the casting modulus by dividing into soft single geometry method has a large workload and low data accuracy, and using three-dimensional engineering drawing to calculate the modulus will be more accurate and efficient. According to the calculation, the modulus MC of the casting is 4.5cm, and the expanded pouring number f of the open riser is 1.2, then the riser modulus MR is calculated to be 5.4cm according to the formula.

When pouring horizontally, the riser is placed on the theoretical plane of the casting. Due to the large area of the layout surface, the standard cylindrical open riser can be placed. According to the casting manual, the modulus of the open riser with D 340mm × h340mm is 5.66cm, which meets the design requirements. When the carbon content of cast steel is 0.1% ~ 0.3% and the pouring temperature is over 1600 ℃, the value of ε is about 5%. After pouring, the top of the riser is covered with a layer of insulation material, so the feeding efficiency of the riser is 15% of the upper limit. According to the formula, 5% × (V riser + V casting) = 3228cm3, V riser × 15% = 4628cm3. It can be seen that 3228cm3 is less than 4628cm3, which meets the design requirements.

In order to increase the feeding channel of the riser, the waist round riser is designed, with the width × length × height = 240mm × 320mm × 360mm, and the modulus is 5.6CM. According to the feeding liquid volume method, 5% × (V riser + V casting) = 2780cm3, V riser × 15% = 3288cm3, it can be seen that 2780cm3 ＜ 3288cm3, which meets the design requirements.

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