JP3942292B2 - Excavation casing for hard soil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a casing structure for excavating a circular shaft in a hard soil ground.
[0002]
[Prior art]
The method of excavating a shaft with a circular casing is to hold a circular casing with an excavating blade tip at the tip with an excavator, apply pressure input and rotational movement in the circumferential direction to cause the excavation to sink, and the ground in the casing with a bucket Perform excavation and earth removal. There are three types of rotational movement of the casing: a method of continuously turning in one direction, a method of turning inversion sometimes, and a method of performing a reciprocating rotary motion every minute.
[0003]
When the natural ground is soft, the circular casing's drilling edge is made of saw-toothed mild steel plate, but as the natural ground becomes harder, hardened edge and hard alloy edge are used. However, the ultimate cutting edge is a cemented carbide cutting edge.
[0004]
The life of the shaft edge of the shaft casing must be maintained until at least one shaft is completed. Otherwise, the construction of the excavated part may be destroyed in the middle of the construction to remove the casing, It is necessary to replace the cutting edge in the shaft with a risk.
[0005]
Cemented carbide is a powder obtained by sintering carbide powder such as tungsten or titanium using iron or nickel as a binder, and is characterized by being extremely hard and excellent in toughness and heat resistance. Although it is mainly used for cutting tools for metal cutting, it has recently been frequently used for excavating blades for civil engineering construction. Cemented carbide blades for shaft excavation casings are usually attached by welding a cemented carbide chip with a hard steel base directly to the casing or by bolting.
[0006]
When drilling a hard soil ground using a cemented carbide cutting edge, the cemented carbide tip itself is not easily worn, but the so-called No. 2 cemented carbide chip holding base or the welded part of the platform is hard soil In many cases, the excavation blade tip falls off and becomes unusable before the cemented carbide chip is worn out due to friction with the excavation scrap.
[0007]
[Problems that the Invention is to Solve
The wear of the second part of the cemented carbide cutting edge of the circular casing is prevented, and the life of the cutting edge is extended until at least one shaft has been excavated.
[0008]
[Means for Solving the Problems]
The reason why the second part of the cemented carbide chip is worn is that hard earth excavated debris enters between the second part of the ground and the cutting edge and wears by friction. Therefore, a hard block is attached in front of the direction of travel of the cemented carbide cutting edge so that excavated soil does not enter between the cutting edge and the ground. This block must be hard, but it can be processed into an arbitrary shape and is suitable for its price. It should be hardened or brazed with cemented carbide grains, so-called composite lots. Is appropriate.
[0009]
The composite lot is made of tungsten carbide particles of about 1 mm to 10 mm wrapped in a brazing material to form a rod shape. This is welded to the base material with a gas torch to form a metal block containing tungsten carbide particles.
[0010]
The block is arranged before the cemented carbide cutting edge when the casing is rotated in one direction, and before and after the cemented carbide cutting edge when rotating the casing reciprocally.
[0011]
The method of arranging the cemented carbide blade tips at the tip of the casing is to attach so-called clams that are alternately arranged with the outer blade that cuts the ground on the outside of the casing and the inner blade that cuts the inner ground, but outside the number of inner blade Increasing the number of blades improves excretion of excavated soil.
[0012]
When high pressure water of 10 to 100 kilograms per square centimeter is sprayed on the excavation blade tip, the excavation earth and sand are washed and the effect of removing excavation waste is increased. If this high-pressure water is supplied from the ground to the cutting edge, the water supply pipe is easily damaged when the bucket is moved in and out of the casing. Also, if the water supply pipe is piped outside the casing, it will be crushed by the clamp band of the excavator or it will interfere with excavation. Therefore, a thick steel pipe having a diameter similar to the plate thickness of the casing shell is cut into the plate thickness and welded. In the method of supplying high-pressure water to the water supply pipe from the ground equipment to the casing, if the casing is reciprocating, it is supplied by a hose, and if it is one-way, it is supplied via an appropriate swivel joint.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an example of a cemented carbide cutting edge 1 that moves in one direction, and FIG. 2 shows an example of a cemented carbide cutting edge 1 that reciprocates. In either case, a cemented carbide chip 2 is brazed to a base 3 made of mild steel.
[0014]
FIG. 3 shows an example of the arrangement of the cemented carbide cutting edge 1 and the block 4 when the casing is viewed from below. The cemented carbide cutting edge 1 has an outer blade that cuts the outer periphery and bottom of the casing, and an inner blade that cuts the inner periphery and bottom, and the block 4 is arranged forward with respect to the excavation direction so as to protect each cutting edge. .
[0015]
FIG. 4 is a diagram illustrating the positional relationship between the XX cross section of the cemented carbide cutting edge 1 shown in FIG. 3 and the YY cross section of the block 4 similarly. The block 4 is placed in a position to protect the cemented carbide cutting edge 1 from the ground excavation debris.
[0016]
FIG. 5 shows the XX cross-section of the outer cutter and the ZZ cross-section of the inner cutter shown in FIG. 3 in order to show the positional relationship between the inner cutter and the outer cutter of the cemented carbide cutting edge 1. The outer blade and the inner blade have a widening of the tip corresponding to a saw clam, overcut the casing excavation groove 13 , reduce sliding resistance of the casing shell 12, and facilitate the discharge of excavated soil. I have it.
[0017]
FIG. 6 is a diagram in which an example of the reciprocating blade edge arrangement is developed from the circumferential surface to the plane. The block 4 is arranged at a position sandwiching the cemented carbide cutting edge 1. FIG. 7 shows another example in which the block 4 and the cemented carbide cutting edge 1 are arranged at equal intervals.
[0018]
FIG. 8 is a cross-sectional view of the high-pressure water supply pipe 5 supplied to the cutting edge. Several water supply pipes 5 are cut into the casing shell 12 and welded. Arrangement of the water supply pipe is placed in a position equally dividing the circumference, thereby preventing ovalization of the casing by welding distortion. The outer diameter of the water supply pipe 5 is made smaller than the thickness of the casing shell 12 so that it does not protrude from the thickness of the casing shell 12. Description of the method of supplying water from the high pressure water pump to the water supply pipe 5 is omitted.
[0019]
This high-pressure water is sprayed in the excavation groove 13 (see FIG. 5) excavated with the cemented carbide cutting edge, and the excavation debris on the entire circumference is washed as the casing rotates.
[0020]
【The invention's effect】
The following effects can be achieved by the present invention.
The wear of the cemented carbide cutting edge is eliminated and the life of the expensive cutting edge is extended.
[0021]
The block is attached to a free shape to some extent and is easy to process.
[0022]
When a composite rod is used for the block, the cemented carbide particles outcrop contribute to excavation to some extent.
[0023]
By cleaning the excavation groove with high-pressure jet water, more excavation debris than removed by the block can be excreted.
[0024]
By embedding the high-pressure water pipe for cleaning in the wall thickness of the casing shell, it looks exactly the same as the integral casing, and there is no influence on the inner and outer surfaces of the casing.
[Brief description of the drawings]
FIG. 1 is a diagram of a cemented carbide cutting edge for one-way excavation.
FIG. 2 is a diagram of a cemented carbide cutting edge for bi-directional excavation.
FIG. 3 is a diagram showing an arrangement of excavation blade edges and blocks when a casing is viewed from below.
FIG. 4 is a diagram for explaining the relationship between a cemented carbide cutting edge and a block.
FIG. 5 is a diagram for explaining a relationship between a chamfered chamfer blade set and a drilling groove.
FIG. 6 is a development view of the relationship between the cutting edge and the block of the reciprocating casing.
FIG. 7 is a developed view of another example of the relationship between the cutting edge and the block of the reciprocating casing.
FIG. 8 is a partial cross-sectional view of a casing incorporating a high-pressure water supply pipe.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cemented carbide cutting edge 2 Cemented carbide tip 3 4 Block 5 Water supply pipe 6 Welding 11 Casing 12 Casing shell 13 Excavation groove 14 Excavation direction 15 Ground

Claims (2)

A shaft excavation casing comprising a circular casing and an excavation cutting edge provided at the lower end of the casing, and constructing a circular shaft in the ground by rotating the casing, wherein the cutting edge is formed of a cemented carbide chip. A cemented carbide blade tip comprising a table or a welded portion of the table that holds the cemented carbide chip, the blade tip is an outer blade whose tip extends outside the outer diameter of the casing, and the tip is the casing of constituted by an inner edge extending inward from the inner diameter to the front with respect to the drilling direction of the cemented carbide cutting edge, the cemented carbide hardfacing welding block to protect the pedestal or base of the weld holding the or A circular hard earth shaft excavation casing in which cemented blocks of cemented carbide grains are arranged in an outward direction with respect to the outer blade and inward with respect to the inner blade . The circular hard earth shaft excavation casing according to claim 1, wherein a water supply pipe is buried in the shell of the casing.

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