Patent ID: 9222357
Filing Date: 2015-12-29
Classification: B23Q,E21D,Y10T

Abstract:
1. A bit exchange method for a shield tunneling machine in which a cutter head is supported at a front of a shield body so as to rotate around a shield axis, drilling bits are disposed on a front surface of the cutter head, and worn one of the drilling bits is exchanged from a working space provided in the cutter head, the method comprising: retracting the drilling bit from a drilling position where the drilling bit is protruded forward from a front plate of the cutter head through an opening, to a protruding/retracting hole formed on a holding cylinder in a bit housing case on a back side of the front plate; meanwhile, injecting a filler from the drilling bit into a retraction space containing the retracted drilling bit, covering an opening surface of the holding cylinder by moving a gate plate so as to close an open/close space formed between the front plate and the opening surface of the holding cylinder in the bit housing case; and discharging the filler injected between the gate plate and the drilling bit in the protruding/retracting hole with a pressure reduced to an atmospheric pressure, allowing the gate plate to come into contact with an edge of the protruding/retracting hole at a front of the holding cylinder by a pressure difference between a face collapse earth pressure for pressing the gate plate from a front surface of the gate plate and an atmospheric pressure on a back side of the gate plate, and closing the protruding/retracting hole by pressing a sealant disposed between the edge of the protruding/retracting hole and the gate plate.