JP2741298B2 - Screw conveyor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a screw conveyor.

[0002]

2. Description of the Related Art A screw conveyor is used, for example, in an earth pressure type shield construction method to discharge excavated earth and sand filled in a cutter chamber of a shield machine. The screw conveyor is generally provided with a cylindrical casing having an inlet and an outlet for earth and sand formed therein, a rotating shaft disposed coaxially with the casing inside the casing, and attached to the rotating shaft. And a screw blade, and earth and sand are transferred in the casing by rotation of the rotating shaft.

[0003] As a screw conveyor of this kind, a stationary space (sand plug zone) is provided in a casing by removing a screw blade from a rotating shaft portion near a discharge opening, and a stop by compaction of earth and sand in the stationary space. 2. Description of the Related Art There is known a structure that uses a water effect to prevent eruption at a discharge port.

[0004]

However, in a screw conveyor provided with such a stationary space, in the case of highly permeable gravel or coarse sand, the internal friction angle of the soil near the boundary between the screw blade and the stationary space. Is likely to occur, and as a result, a phenomenon of causing blockage in a stationary space occurs. Therefore, there was a problem that the shield excavation work was interrupted, the screw blades were damaged, or a driving machine having a large rotating torque was required in order to stably discharge the soil. The present invention has been devised in view of the above circumstances, and an object of the present invention is to prevent the occurrence of a blockage phenomenon in a stationary space without the need for a driving device having a large rotating torque by a simple configuration, An object of the present invention is to provide a screw conveyor capable of preventing damage to blades and stably discharging soil.

[0005]

In order to achieve the above object, the present invention has a cylindrical shape and a predetermined length, and has an inlet for earth and sand at one end in the longitudinal direction and a discharge opening at the other end. A casing, a rotating shaft disposed coaxially with the casing inside the casing, and a screw blade attached to the rotating shaft, wherein the screw blade is rotated from a portion of the rotating shaft near the discharge port. In the screw conveyor in which the stationary space is provided in the casing by removing, the outer diameter of the screw blade near the stationary space is formed smaller than the outer diameter of the screw blade on the inlet side over a predetermined axial length. Is characterized in that a closed buffer space is provided on the upstream side.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view of a screw conveyor in use, FIG. 2 is an enlarged sectional view of a main part of the screw conveyor, and FIG.
5 to FIG. 5 are views taken along arrows AA, BB, and CC of FIG. 2, respectively. 1 is earth pressure type shield machine, 3 is cutter, 5
Is a cutter chamber, and excavated earth and sand in the cutter chamber 5 is transferred backward by the screw conveyor 7,
Furthermore, it is transported backward by the belt conveyor 9.

The screw conveyor 7 includes a casing 11
, A rotating shaft 13 and a screw blade 15. The casing 11 is cylindrical and has a predetermined length, and has an inlet 17 for earth and sand at one end in the longitudinal direction and a discharge port 19 at the other end.
Are formed. The inlet 17 is disposed in the cutter chamber 5, and the discharging port 19 faces above the belt conveyor 9, and the drive unit 2 is provided at the end of the casing 11 on the discharging port 19 side.
1 is attached. The rotating shaft 13 is the casing 11
Is arranged coaxially with the casing 11 inside, and is rotationally driven by a driving machine 21. The screw blade 15 is spirally wound around the rotation shaft 13, and has an outer diameter that is large enough to face the inner peripheral surface of the casing 11. The rotating shaft portion 13A near the discharge port 19 is provided with the screw blade 15
Is removed over a predetermined axial length and this part 13
A and the casing 11 form a stationary space 23.

The portion of the screw blade 15 near the stationary space 23 is formed over a predetermined length L by a small-diameter portion 15A having an outer diameter smaller than that of the upstream portion thereof. Space 25
Is configured. In this embodiment, the outer diameter of the screw blade 15 of the small diameter portion 15A is formed to be の of the outer diameter of the screw blade 15 on the upstream side, and the upstream screw blade 15 and the screw blade 15 of the small diameter portion 15A are formed. The outer diameter of the blade at the boundary is gradually reduced as it reaches the closed buffer space 25.

Next, the operation will be described. At the time of tunnel excavation, the earth and sand in the cutter chamber 5 is transferred from the inlet 17 of the casing 11 to the earth discharging port 19 by the driving of the screw conveyor 7 and discharged from the earth discharging port 19. In the closing buffer space 25, the stationary space 2 is rotated by the rotation of the small outer diameter screw blades 15 constituting the small diameter portion 15A.
Blockage of the earth and sand moving to 3 is alleviated. Therefore, the conventional blocking phenomenon that tends to occur in the stationary space 23 can be mitigated, and at the same time, the spout at the discharge port 19 can be prevented by the water stopping effect in the stationary space 23. Therefore, according to the present embodiment, the simple configuration of reducing the outer diameter of the screw blade 15 can prevent the occurrence of the blocking phenomenon in the stationary space 23 without the need for the driving device 21 having a large rotating torque, and 15 can be prevented from being damaged and soil can be discharged stably.

In the embodiment, the screw conveyor 7 used for discharging the soil by the mud pressure shield method is applied, but the use of the screw conveyor of the present invention is not limited to this, and is optional.

[0011]

As is apparent from the above description, according to the present invention, a closed structure in which the outer diameter of the screw blade is reduced is provided in front of the stationary space.
It is possible to prevent the occurrence of a blocking phenomenon in a stationary space without requiring a driving machine having a large rotation torque, and it is possible to prevent damage to the screw blades and stably perform earth removal.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a use state of a screw conveyor.

FIG. 2 is an enlarged sectional view of a main part of the screw conveyor.

FIG. 3 is a view taken along line AA of FIG. 2;

FIG. 4 is a view taken in the direction of arrows BB in FIG. 2;

FIG. 5 is a view taken along line CC in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Earth-pressure shield machine 7 Screw conveyor 11 Casing 13 Rotary shaft 15 Screw blade 17 Inlet 19 Discharge port 23 Stationary space 25 Closed buffer space

Claims (1)

(57) [Claims] 1. A casing having a cylindrical shape having a predetermined length, an inlet for earth and sand formed at one end in the longitudinal direction, and a discharge opening formed at the other end, and a coaxial interior of the casing inside the casing. A rotary shaft disposed on the rotary shaft, comprising a screw blade attached to the rotary shaft, a screw conveyor provided with a stationary space in the casing by removing the screw blade from the rotary shaft portion near the discharge port, An outer diameter of the screw blade near the stationary space is formed to be smaller than an outer diameter of the screw blade on the inlet side over a predetermined axial length, and a closed buffer space is provided upstream of the stationary space. And screw conveyor.