Chills & Chill Placement for Hot Spots
冷铁与激冷布置控制厚壁热节
标签：冷铁, 激冷, 热节, 顺序凝固
铜合金导热快但厚壁热节仍难补缩，冷铁可将局部凝固速度提高 2–3 倍实现顺序凝固。布置原则：外冷铁厚取热节厚 0.6–0.9 倍、间距 ≤ 冷铁厚 1.5 倍以避免「热节迁移」；与铸件接触面刷涂料防白口/激脆。黄铜厚断面配合冒口使用时，冒口模数应 ≥ 热节模数 1.2 倍；冷铁过厚反而造成表面皱皮，需 X 光验证内部致密度后调整。
Copper conducts heat fast, but thick hot spots still feed poorly; chills raise local solidification rate 2–3× for directional solidification. Rules: external chill thickness 0.6–0.9× hot-spot thickness, spacing ≤1.5× chill thickness to avoid shifting the hot spot, and coat chill faces to prevent chilled hard spots. With risers on thick brass sections, riser modulus ≥1.2× the hot spot; overly thick chills cause surface wrinkling—verify with radiography and iterate.