JP5833955B2 - Steel pipe foundation - Google Patents

Description

  The present invention relates to a steel pipe foundation used when a pole body such as an electric pole is built on the ground, and a steel pipe foundation provided with a tip claw for cutting the ground at the tip of the steel pipe foundation to be rotationally pressed with an earth auger. About.

  Conventionally, it has been carried out that steel pipe foundations are buried in a predetermined ground, and these pillar bodies are built by inserting and fixing pillars such as electric poles, streets or signal lights inside the steel pipe foundation. . At this time, it is possible to improve the efficiency of construction by rotating and pressing the steel pipe foundation into the ground using an earth auger vehicle of a small general purpose heavy machine.

  Here, Patent Document 1 is referred to as a conventional example of such a steel pipe foundation. In this document, a foundation pipe 22 having a plurality of cutting blades 21 fixed to the tip is used as the steel pipe foundation 20, and the foundation pipe 22 is rotated by a screw auger provided in an earth auger vehicle to thereby obtain a predetermined depth of the ground. It is press-fitted into a buried state.

  By the way, as shown to Fig.8 (a), (b), the cutting blade 21 fixed along the outer peripheral surface of the lower end part of the conventional steel pipe foundation 20 is formed by the plate-shaped blade shape. Therefore, when such a steel pipe foundation 20 is rotated with respect to the soil with an earth auger wheel, as shown in FIG. 9A, the cutting blade 21 excavates while cutting the ground E into a circle as the steel pipe foundation 20 rotates. Will proceed.

  However, as shown in FIG. 9B, the respective cutting blades 21 are worn as the excavation progresses, and the initial sharp cutting edge angle increases, resulting in a disadvantage that the excavation efficiency of the cutting blade 21 is significantly reduced.

  Further, as the wear of each cutting blade 21 progresses, as shown in FIG. 9B, the outer periphery of the steel pipe foundation 20 comes into contact with the inner periphery of the excavation hole H, and a load is generated on the rotational power of the earth auger wheel. . For this reason, a large earth auger vehicle is required to increase the work efficiency of excavation.

  Further, in order to solve such a problem, if the thickness of the cutting blade 21 is increased, the life of the cutting blade 21 is extended, but the inner diameter of the excavation hole H is increased, and the steel pipe foundation 20 and the excavation hole H after installation are increased. The gap between and becomes an unstable foundation.

  Further, according to the shape of the conventional cutting blade 21, a plurality of types of cutting blades 21 are required by changing the plate thickness depending on the state of the ground E or changing the gradient angle of the blade.

Japanese Patent Publication No. 8-6544

  The present invention has been made in view of the above circumstances, and relates to the improvement of a steel pipe foundation used when building a pole body such as a utility pole on the ground, and in particular, a tip claw provided at the tip of the steel pipe foundation. An object of the present invention is to provide a steel pipe foundation that can be efficiently excavated by improving the structure. In the present invention, the “cutting blade” in the prior art is referred to as “tip claw”.

In order to achieve the above object, claim 1 of the present invention is a steel pipe foundation in which a plurality of tip claws are provided on the outer peripheral surface of the lower end portion of a steel pipe that is rotationally press-fitted into the ground. It has a mounting portion for mounting and a blade portion formed on the tip side of each tip claw, and the blade portion has a sharp cutting edge in the rotation direction of the steel pipe, and rises in an arc shape toward the outside of each tip claw raised portions have a was,該隆Okoshibu is characterized in that a shape down gently downward with the cutting edge with raised arc from near the top of the outer surface of the tip nail.

  Moreover, Claim 2 of this invention forms the clearance gap adjustment part which consists of a single or several level | step difference surface between the attachment part provided in the inner side of the front-end | tip nail | claw, and a blade part in Claim 1, and lower end of a steel pipe The gap between the tip claw and the wall surface of the excavation hole is adjusted by applying only the attachment surface of the tip claw to the outer peripheral surface or the inner peripheral surface of the portion or by fixing the gap adjustment portion in a predetermined position. It is characterized by doing so.

  Further, according to a third aspect of the present invention, in the first or second aspect, an escape portion having an inclined surface from the blade tip is formed inside the tip claw, and the blade tip of the tip claw is formed in the excavation hole by rotating and pressing the steel pipe into the soil. The same blade edge angle is maintained from the start of excavation to the end of excavation.

  According to the steel pipe foundation of claim 1 of the present invention, the plurality of tip claws fixed to the lower end portion of the steel pipe have a raised portion that is raised in an arc shape toward the outside, so that when the steel pipe is rotationally press-fitted into the soil, the tip The raised portion of the claw pushes and expands the wall surface of the excavation hole, and as a reaction, the wall surface of the excavation hole is easily restored, and the gap between the steel pipe inserted into the excavation hole and the excavation hole can be filled.

  In addition, since the outer surface of each tip claw has a raised portion that protrudes in an arc shape toward the outside, even after the raised portion of each tip claw is polished by the wall surface of the excavation hole due to the rotary press-fitting of the steel pipe, The raised shape can be maintained. Therefore, it is possible to eliminate the inconvenience that the tip claw polished as in the past adheres to the wall surface of the excavation hole and the load during rotation increases.

  Moreover, in Claim 2, since the clearance gap adjustment part which consists of a single or several level | step difference surface is formed between the attaching part provided in the front-end | tip nail | claw, and the blade part, the front-end | tip nail | claw is formed in the peripheral surface of the lower end part of a steel pipe. It is possible to adjust the clearance between the tip claws inclined toward the outside by fixing the mounting surface in a state where the mounting surface is applied or fixing the clearance adjustment portion in a predetermined position. Accordingly, in such a configuration, by fixing the tip claw with the attachment angle adjusted, it is possible to change the outer diameter when the tip claw rotates.

  Furthermore, by fixing the tip claw with its mounting angle adjusted as described above, the cutting diameter can be changed, and the optimum friction performance according to the ground condition, that is, wear on the wall surface of the drilling hole is reduced. It becomes possible.

  Furthermore, in Claim 3, since the escape part which makes an inclined surface from a blade edge | tip is formed in the attachment surface side of a front-end | tip nail | claw, when rotatingly press-fitting a steel pipe in soil, the soil of the wall surface of a digging hole becomes an abrasive. By polishing the tip of the tip claw, it is possible to maintain a sharp cutting edge and maintain the same cutting edge angle from the start of excavation to the end of excavation.

It is a figure which shows the steel pipe foundation which concerns on the Example of this invention, (a) is a side view of a lower end part, (b) is a figure which shows the lower end of a steel pipe. It is an external view which shows the front-end | tip nail | claw of the steel pipe foundation based on the Example of this invention, (a) shows the front-end | tip claw of Example 1, (b) shows the front-end | tip claw of Example 2. FIG. It is a figure which shows the front-end | tip nail | claw of the steel pipe foundation based on Example 1 of this invention, (a) is an inner side view, (b) is an outer side view, (c) is a side view, (d) is an attachment part side. End view, (e) is an end view on the blade portion side. (a) And (b) is a figure which shows the state which fixed the front-end | tip nail | claw which concerns on Example 1 of this invention to the outer peripheral surface of the lower end part of a steel pipe by changing the attachment angle. It is a figure which shows the front-end | tip nail | claw of the steel pipe foundation based on Example 2 of this invention, (a) is an inner side view, (b) is an outer side view, (c) is a side view, (d) is an attachment part side. End view, (e) is an end view on the blade portion side. (a)-(c) is a figure which shows the state which fixed the front-end | tip nail | claw which concerns on Example 2 of this invention to the outer peripheral surface of the lower end part of a steel pipe by changing the attachment angle. (a) And (b) is a figure which shows the condition of the blade edge | tip angle when the front-end | tip nail | claw of the steel pipe foundation based on this invention is grind | polished by the wall surface of an excavation hole. It is a figure which shows the conventional steel pipe foundation, (a) is a side view of a lower end part, (b) is a perspective view which shows a cutting blade. (a) And (b) is a figure which shows the condition of the blade edge | tip angle when the front-end | tip nail | claw of the conventional steel pipe foundation is grind | polished by the wall surface of an excavation hole.

  As shown in FIGS. 1A and 1B, the steel pipe foundation 1 of the present embodiment fixes a plurality of tip claws 3 at predetermined intervals along the outer peripheral surface 2a of the lower end portion of the steel pipe 2 that is rotationally press-fitted into the ground. It is a thing. In this embodiment, the four tip claws 3 are fixed at equal intervals along the outer peripheral surface 2a of the lower end portion of the steel pipe 2. However, the number of other tip ends is not limited to this number. You may make it attach the nail | claw 3. FIG. Moreover, you may fix a front-end | tip nail | claw along the internal peripheral surface 2b of the steel pipe 2. FIG.

  Further, in this embodiment, the tip claws 3 attached to the steel pipe 2 are two kinds of tip claws 3 as shown in FIGS. 2 (a) and 2 (b). 3, it has an attachment portion 4 for attachment to the outer peripheral surface 2 a of the lower end portion of the steel pipe 2 and a blade portion 5 formed on the distal end side of each distal claw 3. Further, the blade portion 5 has a blade edge 6 in the rotation direction of the steel pipe 2 and a shape having a raised portion 7 that protrudes in an arc shape toward the outside of each tip claw 3.

  Further, as shown in FIGS. 2A and 2B, the tip claw 3 has a single or a plurality of step surfaces 8 between the inner surface 11 of the attachment portion 4 of the tip claw 3 and the blade portion 5. , 8a and 8b are formed as gap adjusting portions 10. With such a configuration, as shown in FIGS. 4 and 6, the inner surface 11 of the tip claw 3 is applied to the outer peripheral surface 2 a of the lower end portion of the steel pipe 2, or the step surfaces 8, 8 a, 8 b of the gap adjusting portion 10. It is possible to adjust the gap between the tip claw 3 and the wall surface W of the outer excavation hole H by fixing in a state where any one of the predetermined positions is applied.

  Further, the tip claw 3 has an inclined relief portion 12 formed from the cutting edge 6 on the inner side thereof, and the cutting edge 6 of the tip claw 3 is turned into the wall surface of the excavation hole H by rotationally press-fitting the steel pipe 2 into the soil. By polishing with W, it is possible to maintain the same edge angle from the start of excavation to the end of excavation.

  Hereinafter, as an embodiment of the present invention, the configuration of each tip claw shown in FIGS. 2 (a) and 2 (b) will be described separately in Embodiment 1 and Embodiment 2. FIG.

  The tip claw 3 fixed to the steel pipe foundation 1 of this embodiment has a single protruding between the mounting portion 4 and the blade portion 5 provided inside the tip claw 3 as shown in FIG. The clearance adjustment part 10 which consists of this level | step difference surface 8 is formed.

  The configuration of this embodiment will be described with reference to FIGS. 3 (a) to 3 (e). Each tip claw 3 has an outer peripheral surface of the lower end portion of the steel pipe 2 shown in FIGS. 4 (a) and 4 (b). It has the attachment part 4 for attaching to 2a. The mounting portion 4 has an inner surface 11 formed in an arc shape corresponding to the radius of curvature of the outer peripheral surface of the steel pipe 2, and is formed on the outer peripheral surface 2a of the lower end portion of the steel pipe 2 as shown in FIG. When the tip claw 3 is fixed, the inner surface 11 is brought into contact with the outer peripheral surface 2a of the lower end portion of the steel pipe 2, and the upper end of the tip claw 3 is joined by the welded portion 16a. It becomes possible to join by the welding part 16b.

  Further, as shown in FIG. 4 (b), the upper end edge 11 a of the inner surface 11 of the tip claw 3 is brought into contact with the outer peripheral surface 2 a of the lower end portion of the steel pipe 2, and the step surface is formed on the outer peripheral surface 2 a of the lower end portion of the steel pipe 2. 8, the arc shape formed on the upper edge 11 a and the step surface 8 of the inner surface 11 is in contact with the outer peripheral surface 2 a of the lower end portion of the steel pipe 2 in a stable state and joined by the welded portion 16 b. Is possible.

  Further, the blade portion 5 formed on the tip claw 3 has a sharp blade edge 6 as shown in FIGS. 3A, 3B and 3C in the rotation direction of the steel pipe 2, and the outer periphery of the blade edge 6 has a lower end. By making the notched side 13 having a sloped portion, the cutting edge 6 has a shape that can easily bite into the ground.

  Further, as shown in FIG. 3A, the blade portion 5 of the tip claw 3 has a flat portion 14 having a predetermined width along the reverse rotation blade portion 15 of the blade portion 5 on the inner surface 11 of the tip claw 3. Have. Further, a relief portion 12 inclined from the cutting edge 6 having the above-described shape to the flat portion 14 is formed on the inner surface 11 of the tip claw 3, and the gradient angle of the relief portion 12 is formed as shown in FIG. Forms the cutting edge angle α. In addition, said reverse rotation blade part 15 acts as a blade part when rotating the steel pipe 2 in the reverse direction.

  Furthermore, the front-end | tip nail | claw 3 of a present Example has the protruding part 7 which protruded in the arc shape toward the outer side. As shown in FIG. 3 (c), the raised portion 7 of the tip claw 3 forms a raised portion 7 that is raised in an arc shape in the protruding direction of the outer surface from the vicinity of the upper portion to the lower side on the outer surface of the tip claw 3. doing. As shown in FIG. 3B, the alignment of the raised portion 7 extends downward from the vicinity of the upper portion of the outer surface of the tip claw 3 and bends along the notched side 13 of the blade portion 5. And has a shape reaching the lower end. Further, as shown in FIG. 3 (c), when the alignment of the raised portion 7 is viewed from the side, the raised portion 7 gently falls in the downward direction where the blade edge 6 is located while being raised in an arc shape from the vicinity of the upper portion of the outer surface of the tip claw 3. It is supposed to have a shape.

  As a mode of fixing the tip claw 3 having such a configuration to the outer peripheral surface 2a of the lower end portion of the steel pipe 2, as shown in FIG. 4 (a), the inner surface of the tip claw 3 is provided on the outer peripheral surface 2a of the lower end portion of the steel pipe 2. 4 or as shown in FIG. 4 (b), the gap claw G2 between the tip claw 3 and the wall surface W of the excavation hole H is obtained by welding and joining with the stepped surface 8 of the gap adjusting portion 10 being applied. Can be adjusted.

  4 (a) and 4 (b) show that the steel pipe 2 is placed on the ground E, and the tip of the screw auger of the earth auger wheel is locked to the attachment (not shown) provided on the upper part of the steel pipe 2 for rotational press-fitting. By doing this, the situation in the middle of forming the excavation hole H in the ground E is illustrated.

  As shown in these figures, the plurality of tip claws 3 fixed to the outer peripheral surface 2a of the lower end portion of the steel pipe 2 have the raised portions 7 that are raised in an arc toward the outside, so that the steel pipe 2 is rotationally press-fitted into the ground E. In this case, the raised portion 7 of the tip claw 3 pushes and expands the wall surface W of the excavation hole H, and as a reaction, the wall surface W of the excavation hole H is easily restored, and the steel pipe 2 inserted into the excavation hole H and the excavation It becomes possible to fill the gap G with the hole H.

  4B, the upper end edge 11a of the inner surface 11 of the tip claw 3 is brought into contact with the outer peripheral surface 2a of the lower end portion of the steel pipe 2, and the step surface is formed on the outer peripheral surface 2a of the lower end portion of the steel pipe 2. When 8 is contacted and welded, the maximum outer diameter of the tip claw 3 can be changed and the inner diameter of the excavation hole H can be increased by increasing the cutting edge angle of the tip claw 3.

  G1 and G2 shown in FIGS. 4 (a) and 4 (b) indicate gaps between the steel pipe 2 having the same diameter and the wall surface W of the excavation hole H, and when the cutting edge angle of the tip claw 3 is increased, G1 <G2. FIG. 4B shows that the gap G2 in FIG. 4B is larger than the gap G1 in FIG. G1, G2, and G3 described in Examples 2 and 3 to be described later also indicate a gap between the steel pipe 2 having the same diameter and the wall surface W of the excavation hole H. When the blade edge angle is increased, G1 <G2 <G3, which indicates that the gap increases in the order of G1, G2, and G3.

  Further, in this embodiment, as shown in FIGS. 7A and 7B, the outer surface of each tip claw 3 has a raised portion 7 that is raised in an arc shape. It is possible to keep the raised portion 7 on the outer surface of each tip claw 3 even after the outer surface is polished by the wall surface W of the excavation hole H. Therefore, it is possible to eliminate the inconvenience that the tip claw 3 comes into close contact with the wall surface of the excavation hole H due to wear of the tip claw 3 and the load at the time of rotation increases.

  Furthermore, since the escape portion 12 that is inclined from the cutting edge 6 is formed inside the tip claw 3, the cutting edge 6 of the tip claw 3 is polished by the wall surface W of the excavation hole H by rotationally pressing the steel pipe 2 into the soil. This makes it possible to maintain the same edge angle from the start of excavation to the end of excavation.

  As shown in FIG. 2 (b), the tip claw 3 of this embodiment forms stepped surfaces 8 a and 8 b protruding in two stages between the mounting portion 4 and the blade portion 5 provided inside the tip claw 3. The other configurations are the same as those of the first embodiment. Therefore, in the present embodiment, the configuration other than the stepped surfaces 8a and 8b is the same as that shown in FIGS. 3A to 3E of the first embodiment as shown in FIGS. And have the same function and effect.

  However, in the aspect which fixes the front-end | tip nail | claw 3 of a present Example to the outer peripheral surface 2a of the lower end part of the steel pipe 2, as shown in FIG. By applying only the inner surface 11, it is possible to join the upper end portion of the tip claw 3 with the welded portion 16 a and join the portion of the lower stepped surface 8 a with the welded portion 16 b.

  Moreover, as shown in FIG.6 (b), while contacting the upper end edge 11a of the front-end | tip nail | claw 3 with the outer peripheral surface 2a of the lower end part of the steel pipe 2, the upper end part of the front-end | tip claw 3 is joined by the welding part 16a, and the steel pipe 2 It is possible to apply the welded portion 16b so that the lower stepped surface 8a is placed on the outer peripheral surface 2a of the lower end portion of the steel plate.

  Furthermore, as shown in FIG.6 (c), while contacting the upper end edge 11a of the front-end | tip nail | claw 3 with the outer peripheral surface 2a of the lower end part of the steel pipe 2, the upper end part of the front-end | tip claw 3 is joined by the welding part 16a, It is possible to join by the welding part 16b so that the high level | step difference surface 8b may be put on the outer peripheral surface 2a of 2 lower end part.

  According to the configuration of the second embodiment, as shown in FIGS. 6A to 6C, the attachment angle of the tip claw 3 attached to the outer peripheral surface 2a of the lower end portion of the steel pipe 2 is adjusted in three stages. Thus, by increasing the cutting edge angle of the tip claw 3, the maximum outer diameter of the tip claw 3 can be changed, and the inner diameter of the excavation hole H can be enlarged.

  In Examples 1 and 2 described above, the tip claw 3 is configured to be attached to the outer surface 2a of the lower end portion of the steel pipe foundation 1, but the present invention is not limited to such an example, and the steel pipe foundation. 1 may also be attached to the inner side surface 2b of the lower end portion. In this case, the attachment portion 4 of the tip claw 3 is provided on the outer surface 2a of the tip claw 3, and the raised portion 7 raised by a predetermined height is formed on the outer surface 2a of the blade portion 5 to form the cutting edge 6. It is necessary to.

  The steel pipe foundation of the present invention relates to the improvement of a steel pipe foundation used when building a pole body such as a utility pole on the ground, and in particular, by excavating work by improving the tip claw provided at the tip of the steel pipe foundation. It can be used as a steel pipe foundation that can be efficiently performed.

DESCRIPTION OF SYMBOLS 1 Steel pipe foundation 2 Steel pipe 2a Outer peripheral surface 2b of a lower end part Inner peripheral surface 3 of a lower end part 4 Tip nail 4 Attaching part 5 Blade part 6 Cutting edge 7 Raised part 8 Step surface 8a, 8b Step surface 9 Gradient surface 10 Gap adjustment part 11 Inner side surface 11a Upper end edge 12 Escape part 13 Notch side 14 Flat part 15 Reverse rotating blade part 16a, 16b Welding part α Cutting edge angle G1, G2, G3 Gap E Ground H Excavation hole W Wall surface

Claims (3)

In a steel pipe foundation with a plurality of tip claws on the outer peripheral surface of the lower end of the steel pipe that is press-fitted into the ground, each tip claw is attached to the lower end of the steel pipe and a blade formed on the tip side of each tip claw and a section, the blade portion and having a sharp cutting edge in the rotational direction of the steel pipe, have a raised portion that protrudes in an arc toward the outside of the tip nail該隆Okoshibu the outer surface of the tip nail A steel pipe foundation characterized by a shape that rises in an arc from the top and gently descends downward with a cutting edge . A clearance adjustment part consisting of a single or multiple step surfaces is formed between the attachment part provided on the inside of the tip claw and the blade part, and only the attachment surface of the tip claw is provided on the outer peripheral surface or inner peripheral surface of the lower end of the steel pipe. 2. The steel pipe foundation according to claim 1, wherein the gap between the tip claw and the wall surface of the excavation hole is adjusted by applying or fixing the gap adjustment portion in a state where a predetermined portion is applied. . A relief part that forms an inclined surface from the blade tip is formed inside the tip claw, and the tip of the tip claw is polished by the wall surface of the drilling hole by rotating and pressing the steel pipe into the soil, so that the equivalent from the start of excavation to the end of excavation The steel pipe foundation according to claim 1 or 2, wherein the blade edge angle is maintained.