Machining method for large-length-diameter-ratio deep through holes in end face of round plate

The invention discloses a machining method for large-length-diameter-ratio deep through holes in the end face of a round plate. The method includes the following steps that S1, a material plate is fed, wherein the side faces of the material plate at least comprise a pair of parallel positioning faces used for clamping and positioning; S2, the faces of the material plate are held horizontally, machining allowance for forming an internally-cut round plate face is reserved, and the positions of the two ends of each deep through hole are marked on the surface of the material plate; S3, guiding holes are machined, wherein the material plate is clamped on a machine tool through the positioning faces, and the positions A1, A2, A3...An and the positions B1, B2, B3...Bn are each provided with one guiding hole in the directions of the axes of the deep through holes; S4, small through holes are pre-formed through a perforating machine, wherein the perforating machine starts to form the through holes with the hole diameter smaller than the hole diameter required during machining from the guiding holes along the axes; S5, wire-cutting low-speed feeding is performed, and hole expanding is performed till the deep through holes with the hole diameter meeting the machining requirement are formed; and S6, a workpiece is taken down, and the periphery of the material plate is turned till the peripheral face meets the size requirement. The machining method is good in clamping and positioning, and the precision of the machined deep through holes is high.