JP6864802B1 - Cutting bit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting bit having high cutting performance, excellent durability and high reliability in a cutting operation. SOLUTION: The cutting bit can rotate integrally with a casing 1 and can advance and retreat in the radial direction of the casing 1. The cutting bit 51 in the pile cutting device that cuts the existing pile 4 by attaching the cutting bit 51 to the rocking body 44 and pressing the cutting bit 51 against the outer peripheral surface of the existing pile 4 while rotating the casing 1 is shaken. It is configured to include a fixing portion that is detachably fixed to the moving body 44, and a main body portion that is formed so as to extend diagonally from the fixing portion and has a cutting edge made of a super hard material at the front edge portion in the rotation direction. To do. By providing the cutting bit 51, the existing pile 4 can be efficiently cut with almost no restrictions due to the pile type or the pile diameter of the existing pile 4, and a general-purpose pile cutting / removing device provided with the cutting bit 51 can be used. The sex is enhanced, and the cost reduction is promoted. [Selection diagram] FIG. 11

Description

The present invention relates to a cutting bit used in a pile cutting / removing device that cuts and removes an existing pile buried in the soil on the way.

As a method of cutting and removing an existing pile buried in the soil at a predetermined depth position, a method of cutting the existing pile buried in the soil from the outer peripheral side (outer circumference cutting method) and an inner circumference A method of cutting from the side (inner circumference cutting method) is known, but the outer peripheral cutting method with less restrictions from the pile shape is the mainstream.

In this outer peripheral cutting method, for example, as shown in Patent Document 1 and Patent Document 2, a casing driven to be rotated is arranged outside an existing pile buried in the soil and attached to the inner surface side of the casing. A cutting bit is attached to a movable member that is movable in the radial direction of the casing, and the cutting bit is pressed against the existing pile and rotated integrally with the casing. It is designed to be cut, and cutting bits suitable for each construction method are shown.

Japanese Unexamined Patent Publication No. 2019-15576 JP-A-2007-162435

By the way, the pile cutting device shown in Document 1 moves a cylindrical device main body 3 having a first outer cylindrical portion 4 concentrically and the first outer cylindrical portion 4 along the device main body 3. The first driving device 8 (8a, 8b) and the cutting bits 9a, 9b are provided, and the first outer cylindrical portion 4 is attached to the device main body 3 by the first driving device 8 (8a, 8b). By moving along the line, the cutting bits 9a and 9b are configured to stand up on the cross-sectional center side of the device main body 3 or to lie down on the inner peripheral wall 3N side of the device main body 3.

On the outer circumference of the device main body 3, the first upper arm 1 (1a, 1b) and the first lower arm 2 (2a, 2b) stand up on the cross-sectional center side of the device main body 3, or inside the device main body 3. It is provided so as to lie down on the peripheral wall 3N side, and the cutting bits 9a and 9b are formed so as to extend the other end of the first upper arm 1 (1a, 1b).

However, since the cutting bits 9a and 9b are formed so as to extend the other end of the first upper arm 1 (1a, 1b) as described above, the device main body 3 Since the amount of extension from the outer circumference is large and the rigidity in the rotation direction is low, when the tip portion of the cutting bits 9a and 9b is pressed against the pile P to cut the pile P while rotating the cutting bits 9a and 9b, the cutting bit There is a problem in ensuring the strength of 9a and 9b and the reliability of the cutting work.

On the other hand, the underground pile cutting device shown in Document 2 is attached to a casing driver, a casing 5 rotationally driven by the casing driver, and an inner wall of the casing 5 so as to be openable and closable, and has an arcuate horizontal cross-sectional shape. , A plurality of excavated bodies 20 having excavated claws 22 (corresponding to cutting bits) on the lower side, and vertically attached to the upper part of the excavated body 20 on the inner wall of the casing 5, each opens and closes the corresponding excavated body 21. It is supposed to be equipped with a hydraulic cylinder 23.

However, since the excavated body 20 has a semicircular arc shape, all of the large number of excavated claws 22 attached to the excavated body 20 are rarely involved in the cutting work, and some of them are usually located closer to the center in the arcuate direction. Since the excavation claw 22 is only involved in the cutting work, it is uneconomical to provide a large number of excavation claws 22 in terms of the running cost of the cutting device. Further, since the specific structure of the excavation claw 22 is not shown, the cutability of the excavation claw 22 is not clear, and there is a problem in terms of cutting performance.

Therefore, in view of the above problems, the present invention has been made for the purpose of providing a cutting bit having high cutting performance, excellent durability, and high reliability in cutting work.

In the present invention, the following configuration is adopted as a specific means for solving such a problem.

In the first invention of the present application, on the inner peripheral side of a casing that is fitted and inserted on the outer peripheral side of the existing pile so as to include the existing pile and is rotationally driven, the existing pile is integrally rotated with the casing and in the radial direction of the casing. An existing pile that cuts the existing pile by arranging a rocking body that can move forward and backward, attaching a cutting bit to the rocking body, and pressing the cutting bit against the outer peripheral surface of the existing pile while rotating the casing. The cutting bit in the cutting / removing device, the cutting bit is formed at a fixing portion that is detachably fixed to the rocking body and an obliquely extending shape from the fixing portion and at the front edge portion in the rotation direction. It is characterized in that it is provided with a main body portion provided with a cutting edge made of a super hard material.

In the second invention of the present application, in the cutting bit according to the first invention, the cutting edge portion of the main body portion has a clearance angle of 13 ° to 17 ° and a negative rake angle of 6 ° to 10 °. It is characterized by being provided.

In the third invention of the present application, in the cutting bit according to the first or second invention, the cutting edge is integrally formed of a block body having a substantially triangular columnar shape, and is fitted in a receiving groove provided in the main body portion. It is characterized by being fixed together.

(A) First Invention of the Present Application According to the cutting bit according to the first invention of the present application.
(A-1) Since the existing pile can be cut from the outer peripheral side by the cutting bit that rotates integrally with the casing, there is almost no restriction on the pile type (PC pile, steel pipe pile, etc.) of the existing pile or the pile diameter, and the cutting bit can be cut. The versatility of the existing pile cutting / removing device provided is enhanced, and the cost reduction of the cutting / removing device is promoted.
(A-2) Since the cutting bit is detachably attached to a movable member that rotates integrally with the casing, it is easy to replace the cutting bit when it is worn, and as a result, the cutting removal device is running. Costs can be kept low,
Etc. can be obtained.

(B) Second Invention of the Present Application According to the cutting bit according to the second invention of the present application, the following unique effects can be obtained in addition to the effects described in the above (a). That is, in the present invention, by providing the clearance angle in the cutting bit, the contact between the cutting bit and the cutting surface is suppressed in both the PC pile and the steel pipe pile, the cutting into the existing pile is improved, and the cutting efficiency is improved. Further, by providing the cutting bit with a negative rake angle, the strength performance of the cutting bit is improved and its durability is promoted, and as a synergistic effect of these, cutting of an existing pile provided with the cutting bit is performed. The cutting performance in the removing device will be further improved.

(C) Third Invention of the Present Application According to the cutting bit according to the third invention of the present application, the following peculiar effects can be obtained in addition to the effects described in the above (a) or (b). That is, in the present invention, the cutting edge is integrally formed of a block body having a substantially triangular thick plate shape, and a fixing structure is adopted in which the cutting edge is fitted and fixed in the receiving groove provided in the main body portion. The fixing strength of the cutting edge in the bit is improved, and the effect in terms of cutability and durability is remarkable especially in cutting concrete piles such as PC piles in which irregular impacts are easily generated during cutting work. ..

It is an overall view of the cutting removal apparatus of the existing pile to which the cutting bit which concerns on embodiment of this invention is applied. It is a partial cross-sectional enlarged view of the part A of FIG. It is an enlarged external view of the part B of FIG. It is an enlarged cross-sectional view which shows the state at the time of non-operation of a cutting mechanism part. FIG. 4 is a view taken along the line CC of FIG. It is an enlarged cross-sectional view which shows the state at the time of operation of the cutting mechanism part. FIG. 6 is a view taken along the line DD of FIG. It is explanatory drawing of the cutting state of a PC pile. It is explanatory drawing of the cutting state of the cast-in-place pile. It is explanatory drawing of the cutting state of a steel pipe pile. It is an overall perspective view of the cutting bit which concerns on embodiment of this invention. It is a front view and a bottom view of the cutting bit. It is a side view and the bottom view of the cutting bit.

"Overall configuration of existing pile cutting and removing device Z"
FIG. 1 shows an existing pile cutting / removing device Z provided with a cutting bit according to an embodiment of the present invention. The cutting / removing device Z is configured by connecting the casing 1 to the lower side of the auger 3 suspended and supported by a support base such as a leader via a swivel joint 2.

The casing 1 is composed of a pipe body having an inner diameter dimension (for example, about 500 mm to 600 mm) larger than the existing pile to be cut and removed by a predetermined dimension, and in this embodiment, the casing 1 is sequentially connected coaxially. It has a three-divided structure including an upper casing 11, an intermediate casing 12, and a lower casing 13, and the upper end of the upper casing 11 is connected to the lower side of the swivel joint 2.

Then, the casing 1 is driven into the soil along the existing pile 4 (see FIGS. 4 and 5) while being rotated by the auger 3 and is driven into the soil along the existing pile 4 (see FIGS. 4 and 5). At the lower end of the lower casing 13 located at the lowermost end, as shown in an enlarged view in FIG. A plurality of outer excavation blades 15 attached in a radial outward protrusion are provided.

Then, the soil in contact with the outer circumference of the existing pile 4 is cut by each of the tip excavation blades 14 at a position appropriately separated from the outer circumference, and edge cutting is performed. Further, the outer portion of the edge cutting portion is excavated in an annular shape having a predetermined width by the plurality of outer excavation blades 15, and a traveling gap of a guide case 34 described later provided on the outer circumference of the lower end of the lower casing 13 is formed. Reference numeral 17 is a spiral blade for discharging excavated soil.

Although not shown here, in reality, a jet nozzle is provided on the tip side of the lower casing 13, and water supplied from the upper end side of the casing 1 is supplied from the jet nozzle to the lower casing 13. The excavation work is performed by the tip excavation blade 14 and the outer excavation blade 15 while injecting into the vicinity of the tip to promote the collapse of the soil.

Further, in the casing 1, the existing pile 4 is cut after the casing 1 is driven into the periphery of the existing pile 4 to a predetermined depth, and after the cutting, the cut pile is supported from below as a pile support mechanism. A cutting mechanism 30 that also functions, and a driving mechanism 19 that drives the cutting mechanism 30 are provided. Hereinafter, the cutting mechanism 30 and the driving mechanism 19 will be described respectively.

"Cut mechanism 30"
As shown in FIGS. 4 to 7, the cutting mechanism 30 includes a rocking body 44 attached to an inner peripheral surface near the lower end of the lower casing 13 and a rocking lever connected to the center of the outer circumference of the rocking body 44. It is configured to include a 41 and a cam body 33 provided in the lower casing 13 so as to be engaged with the swing lever 41. In this embodiment, the cutting mechanism 30 is arranged at two positions facing each other with the axial center of the lower casing 13 interposed therebetween.

As shown in FIGS. 4 to 7, the rocking body 44 is formed by bending a plate material having a predetermined width into a substantially semicircular shape along the inner surface of the lower casing 13, and both ends thereof are respectively. It is formed so as to extend diagonally upward. Then, as shown in FIG. 5, the rocking body 44 has both ends thereof at the center of one of the two center lines L _b and L _{c extending in the orthogonal direction through the axial center of the lower casing 13.} It is swingably supported by a pair of pivot shafts 43 arranged on the _{pivot axis L d} separated in parallel with the line L _{b by a predetermined interval.}

Therefore, as shown in FIG. 4, the rocking body 44 has a position where its outer surface is substantially parallel to the inner surface of the lower casing 13 (hereinafter, the position of the rocking body 44 at this time is referred to as a “non-operating position”). , between a position proximate been swung axis L _a closer to the axis line L _a of the lower casing 13 as shown in FIG. 6 (hereinafter, the position of the oscillator 44 in this event is called a "working time position") It is possible to swing with.

Further, on the outer surface on the center line L _c of the oscillator 44, one end of the swing lever 41 is pivotally by a connecting pin 42. The other end of the swing lever 41 is connected to the lower rod 23 of the drive mechanism 19 described later via a pivot pin 32 that moves in the vertical direction along the guide slot 35 provided on the guide case 34 side. There is. Further, the lower edge portion of the opening 18 of the lower casing 13 is provided with a cam body 33 that is slidably engaged with a cam surface formed of a peripheral surface on one end side of the rocking body 44.

At its "first position", the swing lever 41 is pulled upward by the lower rod 23 as shown in FIG. 4, and the entire swing lever 41 is housed inside the guide case 34. ing. At this time, the cam surface on one end side of the swing lever 41 is in contact with or close to the upper edge of the cam body 33, and is connected to one end side of the swing lever 41 by the connecting pin 42. The rocking body 44 is set to the "non-operating position".

Further, in the "second position" of the swing lever 41, as shown in FIG. 6, the lower rod 23 pushes the swing lever downward downward, and the cam surface on the lower end side thereof is the lower edge portion of the cam body 33. The lower half portion thereof is pushed out toward the center of the lower casing 13 by sliding contact with the lower casing 13. In response to the displacement of the swing lever 41, the swing body 44 swings and displaces toward the center of the lower casing 13 with the pivot shaft 43 as the center, and is positioned at the "operating position".

Further, the rocking body 44 has a first cutting bit 51 (corresponding to the “cutting bit” in the claims) described below and a second cutting bit that supports the cutting work by the first cutting bit 51. 52 is attached.

The first cutting bit 51 corresponds to the "cutting bit" in the claims, and as shown in FIGS. 11 to 13, a substantially rectangular block-shaped external shape having an inclined surface 51A1 on one side. The main body 51A to which the cutting blade 53 made of cemented carbide is attached in a fitted and fixed state to the receiving groove 51A3 formed in the portion from the inclined surface 51A1 to the bottom surface 51A2, and the above-mentioned cutting of the main body 51A. It is configured to include two plate-shaped fixing portions 51B erected at a position far from the blade 53 and provided with a bolt fixing hole 54. Therefore, the cutting edge 53 portion of the first cutting bit 51 is in a state of extending diagonally downward with respect to the fixed portion 51B.

Further, as shown in FIG. 13, the first cutting bit 51 has a clearance angle of 13 ° to 17 ° (“18 °” in this embodiment) and 6 ° to 6 ° with respect to the cutting direction of the cutting edge 53. A negative rake angle of 10 ° (“8 °” in this embodiment) is provided. Due to this clearance angle, the contact between the first cutting bit 51 and the cut surface of the existing pile is suppressed, the cutting into the existing pile is improved, and the cutting efficiency is improved. Further, by providing the negative rake angle, the strength performance of the first cutting bit 51 is enhanced, and its durability is promoted. The first cutting bit 51 has a particularly high cutting ability for both concrete and metal materials.

Although an attachment to the oscillator 44 of the first cutting bit 51, in this embodiment, as shown in FIGS. 4 and 5, the position on the center line L _c of the oscillator 44, said center in total three position of the two-position separated by appropriate dimensions from each position in the circumferential direction on both sides on the line L _c, the front side of the swinging direction of the swinging body 44 (i.e., the axis L _a closer of the lower casing 13) It is attached by fitting the fixing portion 51b described in 2 to the receiving portion 44c (see FIGS. 12 and 13) provided at the end edge portion and fastening it with a fixing bolt. In this attached state, the first cutting bit is attached. The cutting edge 53 portion of the 51 is in a state of extending obliquely downward by a predetermined amount from the inner surface of the rocking body 44 at a predetermined inclination angle.

In this embodiment, for one oscillator 44 the first bit 51 as mentioned above, although three radially arranged to direct the axis L _a of the lower casing 13, the present The invention is not limited to this, and for example, it is possible to increase or decrease the amount according to various conditions such as the type of the existing pile to be cut and the diameter dimension.

On the other hand, the second cutting bit 52 is manufactured of a cemented carbide material into a triangular columnar shape having a length substantially matching the width dimension of the rocking body 44, and one ridge line portion thereof is used as a cutting edge. Then, the second cutting bit 52 is directed on the inner surface of the rocking body 44 in the axial direction of the rocking body 44 and with the surface facing the cutting blade abutting against the inner surface of the rocking body 44. It is fixed by welding.

In this embodiment, the second cutting bit 52 is welded and fixed on the inner surface of the rocking body 44, but in other embodiments, the second cutting bit 52 is attached to the rocking body 44. It is configured to be detachably fixed on the inner surface, and can be attached and detached according to the cutting work form.

The rocking body 44 configured in this way swings "between the non-operating state position" and the "operating position" in response to the displacement of the swing lever 41 driven by the drive mechanism 19 described later. By displacing, the existing pile 4 is cut by the first cutting bit 51 and the second cutting bit 52.

"Drive mechanism 19"
As shown in FIGS. 1 and 2, the drive mechanism 19 includes a hydraulic cylinder 20 attached to the upper end side of the upper casing 11 of the casing 1, and a swing lever on the hydraulic cylinder 20 and the cutting mechanism 30 side. It is configured to include a rod 21 for connecting 41. Further, the rod 21 has a two-divided structure of an upper rod 22 made of a round bar and a lower rod 23 made of a square bar, and the lower end of the lower rod 23 is connected to the swing lever 41. ..

In this embodiment, corresponding to the provision of two sets of the cutting mechanisms 30, the drive mechanism 19 is also provided at two positions sandwiching the axial center of the casing 1 in the radial direction. .. Then, the swing lever 41 on the cutting mechanism 30 side operates in response to the expansion / contraction movement of the hydraulic cylinder 20, so that the swing body 44 swings between the “non-operating position” and the “operating position”. Moved back and forth.

"Explanation of operation of cutting removal device Z"
Here, an operating state related to cutting and removing the existing pile 4 by the cutting / removing device Z will be described.

A: Preliminary work First, the cutting / removing device Z is suspended and supported on a support base such as a leader, and is positioned and arranged directly above the existing pile 4 to be worked. Then, the hydraulic cylinder 20 of the drive mechanism 19 is reduced, and the rocking body 44 of the cutting mechanism 30 is set to the "non-operating position". Here, as the existing pile 4, a hollow cylindrical PC pile or a PHC pile is assumed.

B: Excavation work Next, the auger 3 is driven to rotate the casing 1 and the casing 1 is lowered, and the casing 1 is lowered while excavating the periphery of the existing pile 4 located inside the casing 1. Let me. Then, when the cutting mechanism 30 reaches the target cutting position of the existing pile 4, the descent of the casing 1 is stopped. At this point, the pair of left and right cutting mechanisms 30 are positioned at the “non-operating position” shown in FIG. 4, and both the first cutting bit 51 and the second cutting bit 52 of the rocking body 44 are already installed. It maintains a non-contact state with respect to the outer peripheral surface of the pile 4.

C: Cutting work Next, while rotating the casing 1, the hydraulic cylinder 20 of the drive mechanism 19 is extended, and the rocking body 44 is "operated" from the "non-operating position" via the rocking lever 41. The time position is changed, and the first cutting bit 51, the scope of claims, the second cutting bit 52 is pressed and urged against the outer peripheral surface of the existing pile 4. Then, the existing pile 4 is cut from the outer peripheral surface of the existing pile 4 in the axial direction by the first cutting bit 51, and a cutting groove is formed that goes around the outer periphery of the existing pile 4, and the first cutting bit 51 continue to retracted into the該切Kezumizo with the progress of cutting (see cutting surface P _b in FIG. 8). When the amount of immersion of the first cutting bit 51 into the cutting groove reaches a predetermined amount, the second cutting bit 52 is pressed against the upper portion of the cutting groove, and the second cutting bit 52 pushes the upper side of the cutting groove. portion is cut upward inclined (see cutting surface P _a in FIG. 8), cuts the space of the first bit 51 is secured, it is possible to continue cutting operations by the first bit 51.

Along with the progress of cutting the existing pile 4 by the first cutting bit 51, the first cutting bit 51 reaches the embedded vertical bars 5 and horizontal bars 6 to cut them, and further from the vertical bars 5 and horizontal bars 6. Cut the concrete part near the center. Then, when the first cutting bit 51 reaches the inner peripheral surface of the existing pile 4, the existing pile 4 becomes a cutting pile 4B above the cutting portion and a remaining pile 4 below it. Be disconnected.

Although it is a rare case, depending on the conditions such as working conditions, the vertical streaks 5 and the horizontal streaks 6 are not completely cut by the first cutting bit 51, and are pushed by the rotation of the first cutting bit 51. It may gradually deform toward the center of the pile and escape. However, in such a case, since the first cutting bit 51 extends from the edge portion of the rocking body 44 toward the center of the existing pile 4, the extending portion of the first cutting bit 51 extends to the reinforcing bar. When the reinforcing bar 5 and the horizontal bar 6 are forcibly twisted and cut by the first cutting bit 51 by being caught on the 5 and the horizontal bar 6 and rotating integrally with the casing 1 in this state. Since the same state as is obtained, no problem occurs. That is, the existing pile 4 is surely cut by the cutting mechanism 30 without being influenced by the cutting form of the vertical bars 5 and the horizontal bars 6.

D: Removal work of the cut pile 4B When the existing pile 4 is cut at a predetermined position and divided into the remaining pile 4A and the cut pile 4B, the rotation of the casing 1 is stopped, while the shaking of the cutting mechanism 30 is performed. The moving body 44 is held in the "operating position". In this state, the excised pile 4B is held in a state of being supported from below by the rocking body 44 itself and the first bit 51 attached to the rocking body 44 itself. Therefore, if the casing 1 is pulled up as it is, the cut pile 4B is removed from the excavation hole integrally with the casing 1.

E: Cutting and removing work when the existing pile 4 is a solid cast-in-place pile In this case as well, the cutting work of the existing pile 4 and the removing work of the cut pile 4B are performed by using a PC pile in which the existing pile 4 is hollow. It is basically the same as the case of a PHC pile, and the cutting work for the PC pile and the PHC pile is only continued until near the center of the pile axis, and the same applies to the cutting for the vertical and horizontal bars. That is, as shown in FIG. 9, in the cut pile 4B, a large substantially truncated cone portion (see cutting surface Pa) concave portion is formed in the cut portion, and in the remaining pile 4A, the concave portion (cutting surface) is formed in the cut portion. See Pb) is formed. Therefore, the cutting and removing device Z can be used to remove the cutting pile 4B without any problem.

F: Cutting and removing work when the existing pile 4 is a steel pipe pile Cutting and removing work when the existing pile 4 is a steel pipe pile Also in this case, basically, cutting work and cutting pile of the existing pile 4 The removal work of 4B is the same as when the existing pile 4 is a hollow PC pile or PHC pile or a cast-in-place pile, but in the case of a steel pipe pile, the cutting depth is the PC pile or PHC. Since it is smaller than piles and cast-in-place piles, specific measures are required.

That is, in the case of steel pipe piles, the pipe wall thickness is smaller than that of PC piles or PHC piles, and the pile cutting work is completed when the depth of cut of the first cutting bit 51 is small. There is almost no need to secure the cutting space of the first cutting bit 51 by the second cutting bit 52 as in the case of the PC pile. Therefore, the second cutting bit 52 is detachably attached to the rocking body 44 in advance, and as shown in FIG. 10, the second cutting bit 52 is used when cutting the steel pipe pile. It is preferable to remove the steel pipe pile from the rocking body 44 and cut the steel pipe pile only with the first cutting bit 51. By doing so, on the cutting pile 4B side, the cutting surface Pa approaches a plane substantially orthogonal to the axis of the steel pipe as much as possible, and unnecessary cutting parts are eliminated, so that the workability of the cutting work as a whole is improved. It will improve.

G: Unique action and effect of the first cutting bit 51 (1) The first cutting bit 51 can cut the existing pile 4 from the outer peripheral side thereof by integrally rotating with the casing 1 and the rocking body 44. There are almost no restrictions due to the pile type (PC pile, steel pipe pile, etc.) of the existing pile 4 or the pile diameter. Therefore, the versatility of the cutting / removing device Z provided with the first cutting bit 51 is enhanced, and the cutting is extended. The cost reduction of the removal device Z is promoted.

(2) Since the first cutting bit 51 is detachably attached to a rocking body that rotates integrally with the casing 1, it is easy to replace the first cutting bit 51 when it is worn. As a result, the running cost of the cutting removal device Z can be suppressed.

(3) Further, by providing the clearance angle in the first cutting bit 51, contact with the cut surface is suppressed in both the PC pile and the steel pipe pile, and the first cutting bit 51 is attached to the existing pile 4. The cut is good, the cutting efficiency is improved, and the strength performance of the first cutting bit 51 is improved by providing the first cutting bit 51 with a negative rake angle, and the durability thereof is promoted. As a synergistic effect of, the cutting performance in the cutting / removing device Z provided with the first cutting bit 51 is further improved.

(4) Further, the cutting edge 53 is integrally formed of a block body having a substantially triangular thick plate shape, and this is fitted and fixed in the receiving groove provided in the main body portion 51A. The fixing strength of the cutting blade 53 on the cutting bit 51 is improved, and in particular, when cutting a concrete pile such as a PC pile in which an irregular impact is likely to be uttered during the cutting work, the effect in terms of cutability and durability is obtained. It is remarkable.

The cutting bit according to the present invention is applied to an existing pile cutting / removing device and can be widely used for cutting / removing existing piles in civil engineering and construction work.

1 ・ ・ Casing 2 ・ ・ Swivel joint 3 ・ ・ Auger 4 ・ ・ Existing pile 5 ・ ・ Vertical bar 6 ・ ・ Horizontal bar 14 ・ ・ Tip excavation blade 15 ・ ・ Outer excavation blade 17 ・ ・ Spiral blade 18 ・ ・ Opening 19 ・・ Drive mechanism 20 ・ ・ Hydraulic cylinder 21 ・ ・ Rod 30 ・ ・ Cutting mechanism 32 ・ ・ Pit pin 33 ・ ・ Cam body 34 ・ ・ Guide case 41 ・ ・ Swing lever 42 ・ ・ Connecting pin 43 ・ ・ Axle 44 ・ ・ Rocking body 51 ・ ・ First cutting bit (cutting bit)
52 ・ ・ 2nd cutting bit 4A ・ ・ Remaining pile 4B ・ ・ Cutting pile Z ・ ・ Cutting and removing device

Claims (3)

On the inner peripheral side of a casing that is fitted and inserted on the outer peripheral side of the existing pile so as to include the existing pile and is rotationally driven, a rocking body that rotates integrally with the casing and is capable of advancing and retreating in the radial direction of the casing is provided. With the cutting bit in the cutting removal device of the existing pile that cuts the existing pile by attaching the cutting bit to the rocking body and pressing the cutting bit against the outer peripheral surface of the existing pile while rotating the casing. There,
The cutting bit is provided with a fixing portion that is detachably fixed to the rocking body and a cutting edge made of cemented carbide at the front edge portion in the rotational direction while being formed so as to extend obliquely from the fixing portion. A cutting bit characterized by being configured with a main body. In claim 1,
A cutting bit characterized in that the cutting edge portion of the main body portion is provided with a clearance angle of 13 ° to 17 ° and a negative rake angle of 6 ° to 10 °. In claim 1 or 2,
The cutting edge is a cutting bit that is integrally formed of a block body having a substantially triangular thick plate shape and is fitted and fixed in a receiving groove provided in the main body portion.

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