JPH0538154Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Field of Industrial Application The present invention relates to a cutting device for use in the all-casing construction method.

b. Prior Art When inserting a casing tube underground using the conventional all-casing construction method, the cutting edge protrudes slightly outward to facilitate insertion.

C. Problems that the invention aims to solve However, the following problems arose as a result.

(1) When inserting into collapsible sandy soil, sand will spill out between the outer circumferential circle created by the cutting edge and the outer circumferential circle of the casing tube, and the sand will become an obstacle when the casing tube is pulled out. There were cases where it became impossible to pull out.

(2) If there was a defect in the casing tube connection or if the outer periphery of the casing tube was uneven, even if the condition described in (1) above was only slight, it may have become impossible to pull out the casing tube.

d Means for solving the problem In the present invention, the cutting edge of the casing tube is made to protrude outward during insertion,
We solved this problem by adopting a structure that retracts inward when it is pulled out.

In other words, the gist is that, in a cutting device for an all-casing construction method in which a large number of cutting edges are attached to the tip of a cutting tube, an outer surface protruding portion that can protrude outward from the tube and an acute angle to the outer surface protruding portion are used. A cutting device for an all-casing construction method comprising a plurality of cutting edges each having an inwardly sloping lower surface of the tube formed so as to be rotatable at a certain angle inwardly of the tube. .

In the drawings, 1 is a casing tube, and 2 is a number of cutting edges attached at intervals to the lower end of the casing tube.

The cutting edge 2 has a projection 3 on the outside thereof.
is provided with a slope 4 at its lower end, and its upper end 5 is fitted into a recess 6 provided at the lower end of the casing tube 1. A gap 9 is formed between the lower end surface 7 of the casing tube 1 and the shoulder portion 8 of the cutting edge 2 during excavation. The cutting edge 2 can thus be pivoted inwardly by an angle α relative to the casing tube 1. 10 is a slope formed on the upper edge of the protrusion 3;
11 is earth and sand.

e Function When the casing tube is inserted, the cutting edge 2 is inserted with the slope 4 formed on its lower surface, so that the outer side of the cutting edge 2 protrudes outward as shown in FIG. 1, and excavates earth and sand. and,
When a load is applied to the cutting edge 2 by the earth and sand 11 when the casing tube is pulled out, the cutting edge 2 rotates inward by an angle α, as shown in Fig. 3, without being subjected to the resistance of the earth and sand. ,
It gets pulled out.

f. Effects of the invention According to the invention, the casing tube can be inserted and pulled out efficiently in a construction method using a casing tube, for example, an all-casing construction method.

[Brief explanation of the drawing]

Figure 1 is an enlarged vertical cross-sectional view taken along line A-A in Figure 2 of the cutting edge of the casing tube, showing the state when it is inserted into the excavation, and Figure 2 shows the state of the cutting edge installed in the casing tube. The perspective view shown in FIG. 3 is a view similar to FIG. 1, showing when the casing tube is pulled out. DESCRIPTION OF SYMBOLS 1... Casing tube, 2... Cutting edge, 3... Projection, 4... Slope, 5... Cutting edge upper end, 6... Casing lower end recess, 9... Gap.

Claims (1)

[Scope of utility model registration request] In a cutting device for an all-casing method in which a number of cutting edges are attached to the tip of a cutting tube, the tube has a protrusion protruding outward and an inward slope formed at an acute angle with respect to the protrusion. A cutting device for an all-casing construction method comprising a plurality of cutting edges each having a shaped lower surface, which are mounted so as to be rotatable at a certain angle toward the inside of the tube.