JP4195855B2 - Screw conveyor applied to tube propulsion equipment - Google Patents

Description

  The present invention relates to a screw conveyor applied to a pipe propulsion device used for propelling a pipe into the ground for laying a pipe line in the ground, in particular, a ground composed of a suspended sand layer.

  For laying underground such as water and sewage pipes, gas pipes, cable pipes, etc., a pipe propulsion device that sequentially pushes multiple pipes consisting of steel pipes and concrete pipes from underground shafts in the ground is used. It has been.

  Some pipe propulsion devices include a screw conveyor for excavating the ground prior to a pipe (propulsion pipe) propelled in the ground and for transporting the sediment generated by the excavation. The screw conveyor includes a tubular casing disposed inside the propulsion pipe, a shaft disposed in the casing, a screw blade surrounding the shaft, and a bit attached to a tip portion of the shaft. Have.

  According to this, the screw conveyor is propelled together with the propulsion pipe by the operation of a hydraulic jack that is installed in the shaft and forms a part of the pipe propulsion device. At this time, the shaft of the screw conveyor is rotationally driven by the rotational drive device installed in the shaft, thereby performing ground excavation by the bit at the tip of the shaft, under the action of the rotating screw blades, The excavated earth and sand taken in the casing is sent through the casing in a direction opposite to the propulsion direction of the propulsion pipe.

  By the way, in excavation in the stagnant sand layer, the amount of excavated soil in the casing becomes excessive due to the earth water pressure in the face, which may cause the face to collapse.

  Conventionally, in order to avoid such collapse of the face, it has been proposed to arrange an elastic cylinder having elasticity around a part of the longitudinal direction of the shaft at least at one location in the casing (described later). Patent Document 1).

  The elastic cylinder body is airtightly fixed to the inner peripheral surface of the casing at both ends thereof, and air is supplied between the elastic cylinder body and the peripheral surface of the casing so that the inside of the casing is used as the shaft. Inflates towards. As a result, the space between the shaft, which is the earth and sand movement space in the casing, and the peripheral surface of the casing is narrowed, and the amount of earth and sand fed in the casing is reduced. As a result, excessive soil uptake is suppressed.

By the way, since the casing of the screw conveyor in the said conventional pipe propulsion apparatus is comprised as what is arrange | positioned inside the said propulsion pipe, a diameter is smaller than the diameter of the said propulsion pipe. For this reason, in particular, when the propulsion pipe has a small diameter, there are cases in which relatively large gravel in the earth and sand generated by excavation cannot be taken into the casing.
JP-A-6-323093

  An object of the present invention is to provide a screw conveyor for a pipe propulsion device that can suppress excessive uptake of earth and sand caused by excavation of the ground during pipe propulsion and can take in relatively large gravel in the excavated earth and sand. Is to provide.

  The present invention relates to a screw conveyor applied to an apparatus for propelling pipes into the ground, and a plurality of pipes propelled into the ground and connected to each other, and the pipes disposed inside the casing as casings. And an elastic cylinder having a portion of the screw blade disposed around the shaft, the screw blade surrounding the periphery of the shaft and a shaft having a bit attached to the tip of the shaft. And an elastic cylinder that is airtightly or liquid-tightly fixed to the shaft at both ends thereof, and an elastic blade having elasticity that spirally surrounds the elastic cylinder, and the elastic cylinder and the elastic blade Is expandable in the radial direction by the supply of fluid between the shaft and the elastic cylinder, and can contact the peripheral surface of the casing. The said elastic blade | wing shall have an outer diameter smaller than the outer diameter of the other part of the said screw blade | wing in a non-expanded state.

  According to the present invention, a part of the screw blades of the screw conveyor is made of an elastic cylinder and elastic blades having elasticity, and a part of the screw blades abuts on the peripheral surface of the casing by expansion due to fluid supply. Since the screw blades are partly expanded, the sectional area of the space defined by the shaft and the peripheral surface of the casing can be reduced by the expansion of a part of the screw blade. It is possible to limit the amount of excavated earth and sand taken in. In addition, since the casing of the screw conveyor is formed with the pipe to be propelled, the intake opening for the excavated earth and sand can be made larger than that of the conventional screw conveyor, thereby comparing in the excavated earth and sand. Large gravel can also be taken into the casing.

  Preferably, the outer diameter of the elastic blade forming a part of the screw blade is set to be smaller than that of the other portion of the screw blade in the non-expanded state. According to this, while securing the feeding capability of the excavation earth and sand which this elastic screw has in the elastic screw, expansion inhibition by the elastic screw of the elastic cylinder located inside the elastic screw, and the peripheral surface of the casing accompanying this The contact obstruction of the elastic cylindrical body to the can be reduced.

  Referring to FIGS. 1, 4 and 5, a screw conveyor of the present invention which is applied to and forms a part of a pipe propulsion device is indicated generally by the numeral 10.

  The screw conveyor 10 includes a plurality of pipes 12 that are propelled in the ground and connected to each other, and a hollow shaft 14 that is disposed inside the casing with the pipes 12 serving as casings, and screw blades 16 that surround the periphery of the hollow shafts 14. And a shaft 14 having a bit 18 attached to the distal end thereof, and the bit 18 is projected from the distal end of the leading tube 12 to the outside.

  The pipe propulsion device includes a hydraulic jack (not shown) for providing thrust to both the pipe 12 and the screw conveyor 10 installed in a shaft (not shown) constructed in the ground, and a screw conveyor. And a rotational power source (not shown) such as a hydraulic motor for rotationally driving the shaft 14 about its axis.

  A pipe 12 made of a concrete pipe, a steel pipe shown in the drawing, or the like is pushed into the ground from the shaft with the shaft 14 under the operation of the hydraulic jack. At this time, the shaft 14 is rotationally driven by the operation of the rotational power source, and the ground 20 is excavated by the bit 18 prior to the propulsion of the pipe 12.

  A bit 18 for excavating the ground 20 is attached to the shaft 14 via a cutter head 22. The cutter head 22 has an outer peripheral surface having a diameter slightly smaller than the inner diameter of the tube 12. It is continuous and surrounds the periphery of the tip of the shaft 14.

  The cutter head 22 also has an opening 24 opened forward in the propelling direction of the pipe, and earth and sand generated by excavation of the ground 20 are taken into the casing, that is, the foremost pipe 12 through the opening 24. The cutter head 22 is further provided with a supply port 26 for a liquid such as muddy water supplied to the earth and sand taken into the casing in order to counteract the soil water pressure of the face when excavating the ground 20. Yes. The supply port 26 is connected to a liquid supply source (not shown) disposed on the ground or in the shaft via a hose 28 disposed in the casing.

  The excavated earth and sand taken in the casing is sent backward in the propulsion direction in the casing by the action of the screw blades 16 that rotate, and finally transported to the ground through the shaft.

  In the screw conveyor 10 according to the present invention, a part of the screw blade 16 (hereinafter referred to as “screw blade portion”) 30 is formed of an elastic material such as rubber (for example, natural rubber having a hardness of 60). ing.

  In the illustrated example, the screw blade portion 30 is located between and adjacent to another screw blade portion 32 located behind the cutter head 22 and the other screw blade portion 34. These other screw blade portions 32, 34 are formed of a metallic material such as steel.

  Also, in the illustrated example, to provide the screw blade portion 30, the shaft 14 has three portions 36, 38, 40 connected to each other corresponding to the screw blade portion 30 and the other two screw blade portions 32, 34, respectively. It is configured.

  Further, in the illustrated example, the outer diameter of the screw blade 16 is set to be smaller in the order of the rear screw blade portion 34, the front screw blade portion 32, and the middle screw blade portion 30. Desirably, all the screw blade portions 30, 32, 34 have the same outer diameter as the rear screw blade portion 34, and are close to the peripheral surface (inner peripheral surface) of the casing 12 like the rear screw blade portion 34. The front screw blade portion 32 is set to a slightly smaller outer diameter than the rear screw blade portion 34 and the screw blade portion 30 is set to a smaller outer diameter for the reasons described later. Yes.

  As for the front screw blade portion 32, the front tube 12 constituting the free end of the casing is lowered by its own weight and easily comes into contact with the front screw blade portion 32. Therefore, the outer diameter of the front screw blade portion 32 is set to be smaller than the outer diameter of the rear screw blade portion 34. Note that the cutter head 22 has a function of supporting the front tube 12 in order to prevent the front tube 12 from descending.

  The screw blade portion 30 formed of an elastic material includes a cylindrical elastic body surrounding the shaft 14, more specifically, the shaft portion 36 corresponding to the screw blade portion 30, that is, an elastic cylinder body 42, and the elastic cylinder body in a spiral shape. The blades are elastic blades, i.e., elastic blades 44. The elastic cylinder body 42 and the elastic blades 44 are preferably formed integrally with the elastic material.

  The elastic cylindrical body 42 has both end portions in contact with the peripheral surfaces of both end portions of the shaft portion 36. The elastic cylinder 42 has two bands 46 that surround each of the two ends 46 and a plurality of bolts that extend through both ends of the band and the elastic cylinder 42 and are screwed to both ends of the shaft portion 36. The shaft portion 36 is fixed to the shaft portion 36 through 48 and is in airtight contact with the shaft portion 36.

  In addition, a recess having an outer diameter smaller than the outer diameter of both end portions, more specifically, a cylindrical surface 48 is formed between both end portions of the shaft portion 36. Therefore, an annular sealed space 50 is formed around the shaft portion 36 by the both end portions of the shaft portion 36, the cylindrical surface 48, and the elastic cylindrical body 42.

  Further, the shaft portion 36 is provided with a hole 52 communicating with the hollow interior and the sealed space 50. The hole 52 is connected to a pressurized air supply (not shown) including an air compressor located on the ground or in the shaft via a hose 54 extending through the shaft portion 36 and the shaft portion 40 behind it. Yes.

  The elastic cylinder body 42 and the elastic blades 44 can expand in the radial direction by the supply of the pressurized air from the pressurized air supply source to the sealed space 50 and can contact the peripheral surface of the casing.

  According to this, by adjusting the supply amount of the pressurized air to the sealed space 50, the expansion amount of both the elastic cylindrical body 42 and the elastic blade 44 (part 30 of the screw blade) can be adjusted. By adjusting the expansion amount, the distance between the shaft portion 30 and the inner peripheral surface of the pipe 12 around the shaft portion, that is, the peripheral surface of the casing is reduced (FIG. 2) or zero (FIG. 3). That is, the cross-sectional area of the space 56 between them can be reduced or made zero.

  In the state shown in FIG. 2, the elastic blades 44 are in contact with the peripheral surface of the casing, but the elastic cylinder 42 is not in contact. In this state, a spiral sealed space 56 having an interval corresponding to the height dimension of the elastic blade 44 is generated between the elastic cylinder 42 and the peripheral surface of the casing, and the excavated earth and sand are in this narrow spiral space. Pass through.

  In the state shown in FIG. 3, the casing is closed (that is, the spiral space 56 disappears) by the contact of both the elastic blades 44 and the elastic cylinder 42 with the peripheral surface of the casing, and the excavated earth and sand are It cannot pass through the casing.

  By adjusting the size of the cross-sectional area of the spiral space 56, the amount of the earth and sand conveyed to the rear in the casing under the feeding action of the screw blade 16 is limited to a smaller one, or That is, the conveyance of earth and sand can be stopped. Thereby, the excessive removal of the excavated earth and sand from the said face and the collapse accompanying the imbalance of the pressure balance of the face accompanying this can be prevented.

  In determining the outer diameter of the screw blade portion 30, the following is taken into consideration. That is, the spiral space 56 is generated when the peripheral surface of the elastic blade 44 is in close contact with the casing (FIG. 2), and the spiral space 56 is lost when the elastic cylindrical body 42 is in close contact with the casing ( 3) (in other words, the tight contact of the elastic cylinder 42 with the casing is not hindered by the elastic blade 44), the outer diameter of the screw blade portion 30 is set to be the elastic cylinder 42 and the elastic blade 44. It is determined in consideration of the type of constituent material, the degree of elasticity, and the like.

  In the present invention, the casing surrounding the shaft 14 and the screw blades 16 is composed of the pipe 12 propelled into the ground, so that the casing is composed of a pipe member other than the pipe 12 and the pipe member is the pipe 12. Compared with the case where it arrange | positions inside, the cross-sectional area of the conveyance path for the said excavation sediment can be made larger. Therefore, even when relatively large gravel is mixed in the excavated earth and sand, it can be taken into the casing and discharged.

  The fluid supplied to the sealed space 50 can be a liquid such as water instead of the pressurized air. At this time, the both ends of the elastic cylinder 42 are fixed to the shaft portion 36 so as to be in a liquid-tight state in which water does not leak.

It is a longitudinal cross-sectional view of a part of the screw conveyor according to the present invention. FIG. 2 is a longitudinal sectional view of a part of the screw conveyor similar to that shown in FIG. 1, in which a part of the screw blades of the screw conveyor is expanded and only the elastic blades are in contact with the peripheral surface of the casing. A screw conveyor similar to that shown in FIG. 1 in which a part of the screw blades of the screw conveyor is expanded, both of the elastic cylinder and the elastic blades are expanded, and these are in contact with the peripheral surface of the casing. It is a one part longitudinal cross-sectional view. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. FIG. 7 is a cross-sectional view taken along line 7-7 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Screw conveyor 12 Pipe 14 Shaft 16 Screw blade | wing 42 Elastic cylinder 36 Elastic blade | wing

Claims (2)

A screw conveyor applied to an apparatus for propelling a tube into the ground,
A plurality of tubes propelled in the ground and connected to each other;
A shaft disposed inside the casing with the tube as a casing, the shaft having a screw blade surrounding the periphery of the shaft and a bit attached to the tip of the shaft,
An elastic cylinder in which a part of the screw blade is a cylindrical elastic cylinder having elasticity arranged around the shaft, and is airtight or liquid-tightly fixed to the shaft at both ends thereof, and the elasticity An elastic blade having elasticity that surrounds the cylinder in a spiral shape, and the elastic cylinder and the elastic blade expand in a radial direction by supplying fluid between the shaft and the elastic cylinder, and the casing Screw conveyor that can come into contact with the peripheral surface of the screw.   The screw conveyor according to claim 1, wherein the elastic blade has an outer diameter smaller than an outer diameter of another portion of the screw blade in a non-expanded state.

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