METHOD FOR MANUFACTURING AND TREATMENT OF CAST IRON TUBING CASTING OF TUNNEL LINING OF UNDERGROUND METRO STRUCTURES Russian patent published in 2018 - IPC E21D5/10 

FIELD: construction.

SUBSTANCE: method includes making a casting model of a predetermined tubing size. Making the upper and the lower half moulds from moulding mixture with using a model. Assembling the casting mould and casting the mould with cast iron molten to 1,200-1,400°C. Wherein after creating a casting tubing model and preparing the materials for the moulding and the core mixtures in mixing runners with vertically rotating rollers, the resulting moulding mixture is fed through a storage hopper to shaking-type moulding machines, and each half-mould is filled with the mixture. Thereinafter their subsequent finishing is carried out, and tubing marking is installed on the lower half-mould, which is then fed to a pass-through gas dryer, in which this half-mould is heated at a temperature of 320-350°C for 35-55 minutes. After that, the heated bottom half-mould is assembled with the "raw" top half-mould by means of fastening them with clamps after preliminary installation of the gating system into the lower half-mould, by means of which molten cast iron is poured into the mould, which is left to cool on a foundry conveyor for 6-18 hours. After cooling and disassembling the casting mould, the gating system is extracted from the lower half-mould, as well as the cassting, which is cleaned, chipped and sent for controlling the presence of foundry defects. Thereinafter, the finally chipped casting is machined. By means of milling 2 parallel and 2 radial sides of a cast tubing preform and their seam grooves simultaneously from both sides, as well as its 4 support pads (bosses), on a bed-type mill and a boring mill to produce shavings with the weight equal to 10-16% of the weight of the finished tubing. Thereinafter, fixing openings are drilled on each said tubing sides by means of a radial drilling machine, with subsequent spotfacing of annular areas for sealing washers, after which drilling and threading in the backfill opening and drilling the openings in the tubing back are carried out.

EFFECT: simplifying the production process of casting and machining the cast tube preform, reducing the energy and labour costs.

1 cl