JP2021038545A - Casing bit and casing pipe tip structure - Google Patents

Abstract

To improve the workability of removing obstacles by actively cutting obstacles such as reinforced concrete.SOLUTION: In a casing bit 11 having a bit body 13 fixed to a tip of a casing pipe and a tip 15 held by the bit body 13, a flat tip flat surface portion 13a and an inclined flat surface portion 13b are formed on the surface of the tip portion of the bit body 13. A conical protruding portion 15a, which is a part of a cemented carbide chip, is formed on a part of these flat surface portions 13a and 13b.SELECTED DRAWING: Figure 1

Description

The present invention relates to a casing bit used for civil engineering work such as foundation pile work, and more particularly to a casing bit capable of satisfactorily crushing and cutting an underground obstacle such as reinforced concrete.

As a casing bit suitable for removing obstacles, there is one disclosed in Patent Document 1 below. This casing bit has a configuration in which chips held in the bit body are arranged so as to line up in the rotation direction of the casing pipe, and a recess for holding the chips is formed in a part of the width direction of the bit body. ..

The casing bit having such a configuration can suppress the chip from falling off. Further, even if the tip in front of the rotation direction is damaged, the tip behind it exerts the excavation ability, so that high durability can be obtained even when excavating an obstacle such as a reinforcing bar.

However, the casing bits up to now, including the casing bit of Patent Document 1, have a mode in which the tip of the tip appears to protrude from the surface of the casing bit, but the tip of the tip has only the unevenness of the casing bit. It follows a certain outline. That is, the tip of the casing bit is not so much as protruding from the surface of the casing bit like an independent peak, but rather as being exposed to the surface along the uneven outer shape.

For this reason, the obstacle has been crushed by acting strongly on the obstacle, but it is weak in terms of the action of sharply cutting and effectively cutting, and the work may take time.

Japanese Unexamined Patent Publication No. 2011-236644

A main object of the present invention is to improve workability by positively and well cutting obstacles.

The means for that is a bit body fixed to the tip of the casing pipe and a casing bit having a chip held by the bit body, and a flat flat surface portion is formed on the surface of the tip portion of the bit body. A side surface in which the base portion of the chip is embedded in a part of the flat surface portion, and the protruding portion of the chip protruding from the flat surface portion is inclined from the direction perpendicular to the flat surface portion in the direction in which the tip end side of the protruding portion becomes thinner. It is a casing bit having.

In this configuration, the protruding portion of the chip has a side surface that protrudes from a flat flat surface portion and is inclined from a direction perpendicular to the flat surface portion to narrow the tip end side of the protruding portion. For this reason, the protruding portion is not a mode in which it is buried in the form along the surface of the flat surface portion, but a mode in which it protrudes from the flat surface portion. The base of the chip having such a protrusion is strongly held by the bit body.

The protruding portion of the tip as described above rotates at the tip of the casing pipe and cuts sharply against an obstacle with a smaller blade angle than before.

According to the present invention, since the chip has a protruding portion protruding from the flat surface portion, the obstacle can be positively and satisfactorily cut. As a result, the workability of removing obstacles can be improved. Moreover, since it cuts well, noise during work can be reduced.

Perspective view of the outer blade casing bit. Front view of the tip of the casing pipe. Front view of the outer blade casing bit. Rear view of the outer blade casing bit. Right side view of the outer blade casing bit. AA sectional view and BB sectional view of FIG. Top view of the outer blade casing bit. A perspective view of the bit body and the tip of the outer blade casing bit. Right side view of the inner blade casing bit. FIG. 2 is a cross-sectional view taken along the line CC of FIG.

An embodiment for carrying out the present invention will be described below with reference to the drawings.

FIG. 1 shows a perspective view of the casing bit 11. As shown in FIG. 2, the casing bit 11 has a bit body 13 fixed to the tip of the casing pipe 12 and a cemented carbide tip 15 held by the bit body 13.

FIG. 2 is a front view showing a part of the tip end portion of the casing pipe 12, and shows the outer peripheral surface of the casing pipe 12. The casing bit 11 is detachably fixed via a holder 16 fixed to the tip of the casing pipe 12.

Such casing bits 11 include an outer blade casing bit 11a (hereinafter, referred to as “outer blade”) directed toward the outer peripheral surface side of the casing pipe 12 and an inner blade casing bit 11b directed toward the inner peripheral surface of the casing pipe 12. (Hereinafter referred to as "inner blade"). In FIG. 2, the casing bit 11 on the right side of the drawing is the outer blade 11a, and the casing bit 11 on the left side of the drawing is the inner blade 11b. The outer blade 11a and the inner blade 11b are alternately fixed at intervals along the circumferential direction.

Of the casing bits 11, the front view of the outer blade 11a is shown in FIG. 3, the rear view is shown in FIG. 4, the right side view is shown in FIG. 5, and the AA cross-sectional view and the BB cross-sectional view of FIG. 3 are shown in FIG. It is shown in a) and (b), respectively. The right side surface is a surface that becomes the front side in the rotation direction when rotating clockwise.

As shown in these figures, flat flat surface portions 13a and 13b are formed on the surface of the tip end portion of the bit body 13, and the base portion 51 of the chip 15 is embedded in a part of the flat surface portions 13a and 13b. Of the chips 15, the projecting portions 15a protruding from the flat surface portions 13a and 13b have side surfaces 15b and 15c inclined in a direction in which the tip end side of the projecting portions 15a becomes thinner from the direction perpendicular to the flat surface portions 13a and 13b.

As shown in FIG. 8, the bit body 13 is held by the holder 16 (see FIG. 2) described above, and therefore has two leg pieces 31 and 32 arranged in parallel with a predetermined gap. .. These leg pieces 31 and 32 have a substantially rectangular shape that is vertically long when viewed from the front. The widths of the leg pieces 31 and 32, that is, the length in the direction corresponding to the circumferential direction of the casing pipe 12 are appropriately set. A bolt hole for fixing the fixing bolt 17 to the holder 16 is formed through a position near the lower part of the center of the pair of leg pieces 31 and 32. The bolt hole 31a of the leg piece 31 located on the outer peripheral surface side of the bit body 13 is a bottle hole for accommodating the head of the inverted conical bolt 17. The bolt hole 32a of the leg piece 32 located on the inner peripheral surface side of the bit body 13 is a bolt hole having a female screw into which the male screw of the bolt 17 is screwed (see (a) in FIG. 6).

A head 33 that integrates the leg pieces 31 and 32 is formed at the tip of the two leg pieces 31 and 32, that is, at the upper end. The base portion 34 located at the lower part of the head 33 has a plate shape, and the width of the base portion 34 is wider than the width of the leg pieces 31 and 32. The thickness of the base portion 34 in the direction corresponding to the thickness of the casing pipe 12 is the same as the distance between the outer surfaces of the pair of leg pieces 31 and 32, that is, the surfaces corresponding to the outer peripheral side and the surfaces corresponding to the inner peripheral side. The outer surfaces of the leg pieces 31 and 32 and the base portion 34 are flush with each other.

The integrated tip portion 35 connected to the head portion 33 before the base portion 34 is narrower than the base portion 34 in the width direction, and the inclined side surface 35a is inclined toward the middle on both side surfaces in the width direction toward the tip side. have. The tip portion 35 has a shape that protrudes toward the outer peripheral side of the casing pipe 12 in the outer blade 11a and toward the inner peripheral side of the casing pipe 12 in the inner blade 11b. In the outer blade 11a, an outer peripheral side inclined surface 35b that is inclined toward the outer peripheral side toward the tip side is formed on the outer peripheral side surface of the tip portion 35 of the bit body 13 of the outer blade 11a. On the other hand, an inner peripheral side inclined surface 35c that is inclined toward the outer peripheral side toward the tip side is formed on the inner peripheral side surface of the tip portion 35 of the bit body 13 of the outer blade 11a. As shown in FIG. 3, which is a front view, the outer peripheral side inclined surface 35b is an isosceles trapezoid for front view. The inner peripheral side inclined surface 35c is also an isosceles trapezoid for front view as shown in FIG. 4 which is a rear view.

The tip portion 35 of the head 33 having the inclined side surface 35a, the outer peripheral side inclined surface 35b, and the inner peripheral side inclined surface 35c has the tip flat portion 13a and the inclined flat portion 13b as the above-mentioned flat portions 13a and 13b. .. The tip flat portion 13a is formed at the tip of the bit body 13, and is horizontal with no inclination in the width direction (left-right direction). In the case of the outer blade 11a, the position of the tip flat portion 13a in the thickness direction of the bit body 13 is closer to the outer peripheral side than the intermediate position in the thickness direction. On the contrary, in the case of the inner blade 11b, the position of the tip flat portion 13a in the thickness direction of the bit body 13 is closer to the inner peripheral side than the intermediate position in the thickness direction.

The inclined flat surface portion 13b is in contact with the tip flat surface portion 13c and is inclined with respect to the tip flat surface portion 13a. In the case of the outer blade 11a, the outer peripheral side inclined surface 35b is directed in the direction corresponding to the outer peripheral side of the casing pipe 12. It is protruding. In the case of the inner blade 11b, the inclined flat surface portion 13b is projected in the direction corresponding to the inner peripheral side of the casing pipe 12 by the inner peripheral side inclined surface 35c.

These flat surface portions 13a and 13b, that is, the tip flat surface portion 13a and the inclined flat surface portion 13b are rectangular in a plan view and are long in the horizontal direction corresponding to the circumferential direction of the casing pipe 12.

The flat surface portions 13a and 13b have recesses 36 for holding the above-mentioned chip 15. The recess 36 is for fixing one chip 15. Since a plurality of chips 15 are provided on the tip flat surface portion 13a and the inclined flat surface portion 13b, a plurality of recesses 36 are formed on the tip flat surface portion 13a and the inclined flat surface portion 13b, respectively.

Specifically, the recesses 36 of the tip flat surface portion 13a and the inclined flat surface portion 13b are lined up in a row along the longitudinal direction of the flat surface portions 13a and 13b. The recess 36 is a circular hole in a plan view having a size that fits in the flat surfaces 13a and 13b. Two recesses 36 are formed in the tip flat surface portion 13a, and three recesses 36 are formed in the inclined flat surface portion 13b at intervals so as not to interfere with each other.

By fixing the tip 15 to these recesses 36, a plurality of projecting portions 15a are provided in a row on the tip flat surface portion 13a and the inclined flat surface portion 13b along the longitudinal direction of the flat surface portions 13a and 13b.

As shown in FIG. 8, the chip 15 fixed to the recess 36 has a cylindrical base 51 having a size to be inserted into the recess 36 and is sharp. The height of the base 51 is shorter than the depth of the recess 36. Specifically, the tip portion 52 beyond the base portion 51 of the chip 15 has a conical shape, and the tip portion 52 is inclined in two stages. That is, of the tip portion 52, the inclination of the portion 52a on the base 51 side and the portion 52b on the tip side are different, and the inclination of the portion 52b on the tip side is gentler than that of the portion 52a on the base side.

The chips 15 held in the five recesses 36 all have the same shape and hardness.

By fixing the chip 15 to the recess 36, the following protruding portion 15a can be obtained. That is, the protruding portion 15a is sharp and has a conical shape. Further, the protruding portion 15a has a different inclination between the side surface 15c of the flat surface portions 13a and 13b side portions (base 51 side portion 52a) and the side surface 15b of the tip end side portion (tip end side portion 52b), and the tip side side surface 15b. The slope is gentler than that of the side surfaces 15c on the flat surface portions 13a and 13b.

The tip 15 is fixed to the recess 36 of the bit body 13 by fitting the base 51 into the recess 36 and brazing or the like. Since the base portion 51 of the chip 15 has a short recess 36, the portion of the chip 15 that protrudes from the flat surface portions 13a and 13b, that is, the portion that becomes the above-mentioned protruding portion 15a is a part of the above-mentioned tip portion 52. is there.

Further, the casing bit 11 has a built-up portion 18 at a portion surrounding the flat surface portions 13a and 13b. The overlay portion 18 reinforces the surface of the bit body 13.

The built-up portion 18 integrally has a raised portion 18a. The raised portion 18a is raised and protruded in the protruding direction of the protruding portion 15a on both sides of the flat surface portions 13a and 13b in the width direction of the tip surface of the bit body 13, that is, on both sides in the direction corresponding to the circumferential direction of the casing pipe 12. It is a portion having a height lower than that of the portion 15a. Specifically, raised portions 18a are formed on both sides of the flat surface portions 13a and 13b in the longitudinal direction of the tip flat surface portion 13a.

The built-up portion 18 including the raised portion 18a has a structure having carbide particles 19. That is, the built-up portion 18 is formed by adhering the cemented carbide particles 19 while welding, as shown by enlarging a part in FIG. 6A. The thickness of the built-up portion 18 is appropriately set, but the height of the portion aligned with the protruding portion 15a in the excavation action direction is made lower than the height of the protruding portion 15a.

The cemented carbide particles 19 used for forming the overlay portion 18 have a spherical shape as shown in FIG. 6A. The sphere shape does not mean only a perfect sphere, but means a shape like a sphere without sharp corners, and it is sufficient if the shape is a sphere or a shape close to it. The cemented carbide particles 19 are not obtained by crushing a waste cemented carbide, but are formed into a spherical shape by powder metallurgy.

The size of the cemented carbide particles 19 depends on the thickness of the overlay portion 18, but is preferably smaller. If the size exceeds several mm, the integralness of the overlay portion 18 may be lowered. However, if it is too small, the workability when forming the built-up portion 18 may deteriorate. Therefore, the particle size of the cemented carbide particles 19 is preferably, for example, about φ0.5 mm to φ2 mm, and more preferably about φ0.5 mm to φ1.5 mm. The size of the cemented carbide particles 19 used may be unified or may vary.

When the size of the cemented carbide particles 19 is within the above-mentioned range, the thickness of the built-up portion 18 is preferably, for example, about 3 mm to 5 mm.

The cemented carbide particles 19 seen in the overlay portion 18 have a spherical shape with no corners, and the overlay portion 18 has a dense appearance as a whole.

FIG. 9 is a right side view of the inner blade 11b. As shown in this figure, the inner blade 11b has a configuration in which the direction of the head 33 of the outer blade 11a is opposite to the inner and outer directions. The right side surface in this case is also the surface that becomes the front side in the rotation direction when rotating clockwise.

The tip structure of the casing pipe 12 in which the outer blade 11a and the inner blade 11b as described above are arranged on the circumference of the tip is as follows (see FIGS. 2 and 10). The bit body 13 of the outer blade 11a and the inner blade 11b has a tip flat surface portion 13a formed at the tip position, and the outer blade 11a has an inclined flat surface portion 13b protruding toward the outer peripheral side of the casing pipe 12. The inner blade has an inclined flat surface portion 13b protruding toward the inner peripheral side of the casing pipe 12.

The base portion 51 of the chip 15 is embedded in a part of the tip flat surface portion 13a and the inclined flat surface portion 13b. Of the chips 15, the protruding portion 15a protruding from the tip flat surface portion 13a or the inclined flat surface portion 13b is the side surfaces 15b, 15c in which the tip end side of the protruding portion 15a is inclined from the direction perpendicular to the tip flat surface portion 13a or the inclined flat surface portion 13b. have. The protruding portion 15a of the tip flat portion 13a of the outer blade 11a is closer to the outer peripheral side than the intermediate position in the thickness direction of the bit body 13, and the protruding portion 15a of the tip flat portion 13a of the inner blade 11b is the bit body 13 It is closer to the inside than the middle position in the thickness direction of.

Therefore, as shown in FIG. 10 which is a cross-sectional view taken along the line CC of FIG. 2, the tip of the casing pipe 12 is located at the same height as the outer blade 11a and the inner blade 11b, but in the thickness direction. It has a tip flat portion 13a that is displaced in the direction of separation. Further, the outer blade 11a has an inclined flat surface portion 13b facing the outer peripheral side, and the inner blade 11b has an inclined flat surface portion 13b facing the inner peripheral side, and a plurality of protruding portions 15a arranged in a row in the circumferential direction of the casing pipe 12, respectively. Has. For this reason, a total of four rows of sharp protrusions 15a, two rows in the propulsion direction and two rows diagonally with respect to the propulsion direction, are sequentially excavated and cut.

In FIG. 10, the arrow A indicates the rotation direction in the case of clockwise rotation.

As described above, the protruding portion 15a of the chip 15 in the casing bit 11 projects so as to stand out from the flat surfaces 13a and 13b of the bit body 13, and also has a side surface that is inclined with respect to the direction perpendicular to the flat surfaces 13a and 13b. It has 15b and 15c. When excavation is performed using such a casing bit 11, the protruding portion 15a of the tip 15 is sharply cut with a small blade angle as the casing pipe 12 rotates. Therefore, even if there is an obstacle such as a reinforcing bar, it can be positively and satisfactorily cut. As a result, obstacles can be removed efficiently. In addition, since obstacles can be cut well, noise during excavation can be reduced and the working environment can be improved as much as possible.

Moreover, since the entire base portion 51 of the chip 15 is embedded in a part of the flat surface portions 13a and 13b, the chip 15 can be strongly held by the bit body 13. Therefore, cutting against obstacles can be reliably performed.

Such a tip 15 is formed not only on the tip flat surface portion 13a but also on an inclined flat surface portion 13b protruding to the outer peripheral side and the inner peripheral side, and four rows of sharp protruding portions 15a sequentially excavate and cut. Therefore, the workability against obstacles is particularly good.

Further, the plurality of projecting portions 15a are arranged in a row along the longitudinal direction of the flat surface portions 13a and 13b, that is, the horizontal direction corresponding to the circumferential direction of the casing pipe 12, and the projecting portions 15a are independent of each other. Therefore, cutting against obstacles can be performed more strongly.

In particular, since the protruding portion 15a has a sharp conical shape, it can be cut satisfactorily.

Further, since the side surfaces 15b and 15c of the protruding portion 15a have a two-step inclination, the strength and durability of the protruding portion 15a itself can be increased.

The durability of the casing bit 11 is enhanced by the built-up portion 18 having the carbide particles 19, and the raised portions 18a are formed on both sides of the protruding portion 15a of the tip flat portion 13a located in the propulsion direction in the rotational direction. Therefore, durability can be obtained while ensuring machinability.

The above configuration is one form for carrying out the present invention, and the present invention is not limited to the above-mentioned configuration, and other configurations may be adopted.

For example, the shape of the protruding portion 15a of the chip 15 may be another shape such as a tapered plate shape in addition to the conical shape as described above. When the protruding portion 15a has a tapered plate shape, the longitudinal direction of the tip of the protruding portion 15a is directed to the horizontal direction corresponding to the circumferential direction of the casing pipe 12.

When fixing a plurality of chips 15, the shape and hardness of the chips 15 may be changed according to the fixed portion.

The mode of the flat surface portion for fixing the chip 15 and the arrangement of the protruding portion 15a can be appropriately designed.

11 ... Casing bit 12 ... Casing pipe 13 ... Bit body 13a ... Tip flat part 13b ... Inclined flat part 15 ... Chip 15a ... Protruding part 15b, 15c ... Side surface 18 ... Overlay part 18a ... Raised part 19 ... Carbide particles 51 ... base

Claims (9)

A casing bit having a bit body fixed to the tip of a casing pipe and a tip held by the bit body.
A flat flat surface is formed on the surface of the tip of the bit body.
The base of the chip is embedded in a part of the flat surface portion.
A casing bit having a side surface in which a protruding portion of the chip protruding from the flat surface portion is inclined from a direction perpendicular to the flat surface portion in a direction in which the tip end side of the protruding portion becomes thinner. The casing bit according to claim 1, wherein the protruding portion of the chip is sharp. The inclination of the side surface is different between the flat portion side portion and the tip end side portion of the protruding portion of the chip.
The casing bit according to claim 1 or 2, wherein the portion on the tip end side has a gentler inclination than the portion on the flat surface portion side. The casing bit according to any one of claims 1 to 3, wherein the protruding portion of the chip has a conical shape. The flat surface portion is in contact with the tip flat surface portion formed at the tip of the bit body and is inclined with respect to the tip flat surface portion, and is an inclined flat surface that protrudes toward the outer peripheral side or the inner peripheral side of the casing pipe. The casing bit according to any one of claims 1 to 4, which is a part. The flat surface portion has a shape long in the horizontal direction corresponding to the circumferential direction of the casing pipe.
The casing bit according to any one of claims 1 to 5, wherein a plurality of the projecting portions are provided in a row on the flat surface portion along the longitudinal direction of the flat surface portion. The casing bit according to any one of claims 1 to 6, wherein a built-up portion having cemented carbide particles is formed in a portion surrounding the flat surface portion. On both sides of the tip surface of the bit body in the flat surface in the direction corresponding to the circumferential direction of the casing pipe, the overhanging portion is integrated with the protrusion in the protruding direction and is higher than the protruding portion. The casing bit according to claim 7, wherein a low ridge is formed. The bit body fixed to the tip of the casing pipe and the casing bit having the tip held by the bit body are the tip structures of the casing pipe arranged on the circumference of the tip.
The outer blade casing bit and the inner blade casing bit are provided as the casing bits, and these are arranged alternately.
The outer blade casing bit and the bit body of the inner blade casing bit have a tip flat portion formed at the tip position and have a tip flat portion.
The outer blade casing bit has an inclined flat surface portion that is in contact with the tip flat surface portion and is inclined with respect to the tip flat surface portion and protrudes to the outer peripheral side of the casing pipe.
The inner blade casing bit has an inclined flat surface portion that is in contact with the tip flat surface portion and is inclined with respect to the tip flat surface portion and protrudes toward the inner peripheral side of the casing pipe.
The base portion of the chip is embedded in the tip flat surface portion and a part of the inclined flat surface portion.
Of the tip, the protruding portion protruding from the tip flat surface portion or the inclined flat surface portion has a side surface that is inclined from a direction perpendicular to the tip flat surface portion or the inclined flat surface portion in a direction in which the tip end side of the protruding portion becomes thinner.
The protruding portion of the tip flat portion of the outer blade casing bit is closer to the outer peripheral side than the intermediate position in the thickness direction of the bit body, and the protruding portion of the tip flat portion of the inner blade casing bit is , The tip structure of the casing pipe that is closer to the inside than the intermediate position in the thickness direction of the bit body.

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