针对煤矿井下复杂顶板高位钻孔穿越破碎层位段下放大直径套管过程中施工效率低、人工劳动强度大等问题，设计了大直径套管下放装置。介绍了大直径套管下放装置的方案制定，详细叙述了前内撑组件、后内撑组件和缸体、卡瓦等关键零部件的设计过程，并简述了利用钻机进行套管下放的工艺步骤。现场工业性试验过程中，向倾角为17°的4个定向钻孔内累计下入直径为ϕ245 mm长度为1.5 m的套管68根，共计102 m；大直径套管下放装置动作灵敏，性能可靠，满足了复杂顶板高位钻孔机械化下放大直径套管的功能需求。

Aiming at the problems such as low construction efficiency and high labor intensity in the process of lowering large diameter casing through the broken stratum of complex roof high level drilling in coal mine, a large diameter casing lowering device is designed. This paper introduces the design of large diameter casing lowering device, describes in detail the design process of front inner support assembly, back inner support assembly, cylinder block, slip and other key parts, and describes the technological steps of casing lowering by drilling rig. During the field industrial test, 68 casings with a diameter of ϕ245 mm and a length of 1.5 m were run in 4 directional boreholes with a tilt angle of 17°, totaling 102 m. The large diameter casing lowering device is sensitive and reliable, and can meet the functional requirements of mechanized large diameter casing lowering in complex roof high level drilling.