JP2009035932A - Excavation tool and excavating bit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform sure excavation by preventing the falling-off of a tip by restraining the abrasion of a body of an excavation bit, when continuously performing the excavation of the ground and the excavation of a buried structure. <P>SOLUTION: The excavation bit 21 implanted so that an excavation tip 23 harder than an excavation bit body 22 projects from the tip surface 25a of the excavation bit body 22, and a protective bit 31 implanted so that a protective tip 33 harder than a protective bit body 32 is exposed to at least one of outer peripheral surfaces 35b in the radial direction to the axis O of the protective bit body 32 are arranged at the tip of a cutter ring 11 rotated around the axis O. This protective bit 31 is arranged so that a rotational locus around the axis O overlaps with the excavation bit 21 in a position where its tip retreats in the axis O direction retreated from the tip of the excavation bit 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, a drilling bit is provided at the tip of a cutter ring rotated about an axis, and in particular, excavation from a soft layer to a medium hard rock layer and excavation of buried objects such as reinforced concrete, steel, steel, and unreinforced concrete. The present invention relates to an excavation tool suitable for continuous use, and an excavation bit suitable for such excavation tool.

  As such excavation tools and excavation bits, for example, in Patent Documents 1 and 2, a plurality of excavation bits are arranged and fixed at the annular end of a cylindrical casing body, A drilling blade member with a rod-shaped chip made of cemented carbide is placed, and on both sides or on the leading side with respect to the drilling direction, an upwardly inclined guide surface is formed toward the drilling blade member There has been proposed a guide member provided with a pair of guide pieces on the side surface of the bit body. Here, the guide member is made of a cemented carbide which is softer than the chip.

Further, the inventors of the present invention also disclosed in Patent Documents 3 and 4 that, as excavation bits attached to the front end of the cutter ring rotated around the axis, a mountain shape that protrudes toward the front end side along the rotation direction of the cutter ring. Proposal is made of a hard chip planted in a chevron shape on the bit body, and a hard chip tilted in the direction of rotation toward the tip side toward the tip end of the bit body. . Furthermore, in these Patent Documents 3 and 4, it is also proposed to plant an auxiliary chip that is harder than the bit body and substantially the same as or softer than the chip on the side surface of the bit body.
JP 2002-322893 A JP 2002-317596 A JP 2000-291365 A JP 2000-291366 A

  By the way, in these excavation bits described in Patent Documents 1 to 4, a rod-shaped or shaft-shaped tip made of cemented carbide is formed on a bit body made of steel or the like so that its longitudinal direction is directed to the axial direction of the cutter ring. It is only planted, and guide members are provided on both sides of the excavating blade member and in the rotational direction as described in Patent Documents 1 and 2, or a bit body as described in Patent Documents 3 and 4 Even if an auxiliary tip is provided on the side surface, these guide members and the auxiliary tip itself do not excavate, so the side surface of the bit body wears especially when it comes into sliding contact with the reinforcing bar or steel part of the buried object. Inevitably, the chip often fell out of the bit body before reaching the end of its life.

  The present invention has been made under such a background, and continuously excavates the soft layer to the medium hard rock layer and the excavation of the reinforced concrete, the steel material, the buried material such as the steel material and the unreinforced concrete. An object of the present invention is to provide a drilling tool capable of suppressing wear of the main body of the drilling bit to prevent chipping and thereby performing reliable drilling, and a drilling bit suitable for use in such a drilling tool. It is said.

  In order to solve the above-mentioned problems and achieve such an object, the excavation tool of the present invention has an excavation tip harder than the excavation bit body at the tip of the cutter ring rotated about the axis. A drilling bit planted so as to protrude from the front end surface of the main body and a protective tip harder than the protective bit main body are planted so as to be exposed on at least one of the radially inner and outer peripheral surfaces of the protective bit main body with respect to the axis line. The protection bit is arranged such that the tip of the protection bit is in a position retracted in the axial direction from the tip of the excavation bit, and the rotation trajectory around the axis overlaps the excavation bit. It is provided.

  That is, in the excavation tool of the present invention, the excavation bit and the protection bit are provided at the front end portion of the cutter ring, and among these, the excavation bit is implanted so that the excavation tip protrudes from the front end surface of the excavation bit body. Then, as the cutter ring is advanced while rotating, the excavation tip excavates the ground and the buried material of the middle hard rock layer from the soft layer while forming an annular groove in cross section. Furthermore, as the excavation is performed in this manner, the excavation tip is worn and the sharpness thereof becomes dull, but at the same time, the distal end surface of the excavation bit body is also worn and the distal end portion of the excavation tip is exposed. Since the tip portion of the excavation tip is damaged by excavation resistance, a new cutting edge is self-generated, so that the sharpness can be recovered and efficient excavation can be performed.

  In the protection bit, a protection tip is implanted in the protection bit body so as to be exposed on at least one of the radially inner and outer peripheral surfaces with respect to the cutter ring axis, and the protection bit recedes from the tip of the excavation bit. Since the rotation trajectory around the axis overlaps with the excavation bit, the protection tip of the protection bit is in sliding contact with the wall surface of the groove excavated by the excavation bit preceding in the axial direction. Thus, the sliding contact between the excavation bit body and the wall surface can be suppressed and the wear thereof can be prevented. In addition, as the drill bit wears from the tip side as described above and the cutting blade of the drill tip is self-generated, the protection bit body wears from the tip side and the protection tip is sequentially dropped. Therefore, the self-growth of the cutting blade of the excavation tip is not hindered, and the excavation tip can be prevented from falling off over the effective length of the excavation tip, and reliable excavation can be promoted.

  Here, the number of protection bits may be small for the drilling bit mainly for excavation, but the number of protections is 0.2 to 0.8 times the number of drilling bits at the tip of the cutter ring. It is desirable to provide a bit, and if it is less than this, the protection effect of the excavation bit may not be expected. On the other hand, if it is too much, the resistance during excavation may increase. Similarly, the end of the protection tip exposed on at least one of the radially inner and outer peripheral surfaces of the protection bit arranged so that the rotation trajectory around the axis overlaps the excavation bit is the radial direction of the excavation bit body in this rotation trajectory. It is desirable for the inner and outer peripheral surfaces on the same side to protrude or retract within a range of up to 2 mm. If the protective tip is retracted more than this, the protection effect of the excavation bit will be insufficient. If it protrudes too far, the excavation resistance will increase.

  Further, with respect to the protruding height H from the tip surface of the cutter ring to the tip of the excavation bit, the tip of the protection bit has a range of 0.2 × H to 0.8 × H from the tip of the excavation bit in the axial direction. It is desirable that the drill bit is retracted larger than this, and the portion where the tip side of the excavation bit is in sliding contact with the wall surface of the groove may be increased, and it may not be possible to reliably extend the service life. On the other hand, if it is smaller than the above range, the wear of the protection bit is promoted excessively against the wear of the drill bit depending on the feed of the cutter ring and the distance between the drill bit and the protection bit in the rotation direction, etc. There is a risk of spending.

  Further, the length from the tip of the drilling bit to the rearmost end of the drilling tip implanted in the main body of the drilling bit in the axial direction, that is, the effective length L of the drilling tip is from the rearmost end of the drilling tip. The height to the tip of the protection bit in the axial direction is preferably in the range of 0.2 × L to 0.8 × L, and if the height of the protection bit is lower than this, the tip of the excavation bit There is a risk that the wear on the side will be so great that the drilling tip cannot be used effectively. Conversely, if the height of the protection bit is higher than this, the wear of the protection bit will be promoted and the protection tip will fall off early. , Its life may be shortened.

  On the other hand, in the excavation bit provided in such an excavation tool, a part of the excavation tip is exposed on at least one of the radially inner and outer peripheral surfaces with respect to the axis of the excavation bit body, and the protection In addition to the bit, the drill bit itself may be used to suppress wear of the drill bit body. However, in this case, if the exposed portion of the excavation tip is too large, it will easily fall off, so that the exposed portion of the excavation tip from at least one of the radially inner and outer peripheral surfaces of the excavation bit body It is desirable that the amount of protrusion of the digging tip is ½ or less of the radial dimension of the excavation tip with respect to the axis.

  As described above, according to the excavation tool of the present invention, the wear of the excavation bit is suppressed by the protective bit without damaging the self-growth of the cutting edge of the excavation tip, and the excavation tip is prevented from falling off. The excavation of the rock layer and the excavation of the reinforced concrete, the steel material, or the buried object such as the steel material and the unreinforced concrete can be performed continuously and efficiently. Further, according to the excavation bit of the present invention, the excavation bit itself can be given an effect of suppressing the wear, and therefore, more efficient excavation can be promoted.

  FIGS. 1 to 3 show an embodiment of the excavation tool of the present invention. FIGS. 4 to 8 show an embodiment of the excavation bit of the present invention used in the excavation tool. FIGS. An example of each protection bit is shown. In the excavation tool according to the present embodiment, the cutter ring 11 is formed in an annular shape or a cylindrical shape centering on the axis O with a steel material or the like, and the front end surface 12 in the direction of the axis O is a plane perpendicular to the axis O. A plurality (15 in this embodiment) of recesses 13 are formed in the distal end surface 12 at intervals in the circumferential direction, and the excavation bit 21 and the protection bit 31 of the above embodiment are arranged in these recesses 13. It is installed.

  Each of the excavation bit 21 and the protection bit 31 has a drill bit body 22 and a protection bit body 32 made of the same steel as the cutter ring 11, respectively, and a cylindrical excavation tip 23 and a protection chip 33 made of cemented carbide. It is constructed and constructed. Further, each of the bit bodies 22 and 32 has a substantially rectangular plate-shaped attachment portion 24 and 34 having a thickness substantially equal to the thickness of the cutter ring 11 in the radial direction, and one of the rectangular surfaces of the attachment portions 24 and 34. Projecting to the longitudinal center of the side surfaces 24a, 34a along the long side of the rectangular parallelepiped block, the longitudinal direction being shorter than the mounting portions 24, 34 and the thickness being thicker than the mounting portions 24, 34 It is set as the structure by which the planting parts 25 and 35 were integrally formed, and the chips 23 and 33 are planted by this planting parts 25 and 35. As shown in FIG.

  In this embodiment, the excavation bit 21 and the protection bit 31 are a plane passing through the center in the thickness direction of the mounting portions 24 and 34, and the center in the longitudinal direction perpendicular to the plane and the side surfaces 24a and 34a. Are formed symmetrically with respect to the plane passing through the. Further, the mounting ridges 24 and 34 are chamfered at the intersection ridge line portion between the rectangular surface and the three side surfaces other than the side surfaces 24a and 34a, and the intersection ridge line portion between these three side surfaces. The portion from the rectangular surface of 24, 34 to the planting portions 25, 35 and the portion from the side surfaces 24a, 34a to the planting portions 25, 35 are each continued by a 1/4 concave cylindrical surface, and the mounting portion The heights from the side surfaces 24 a and 34 a of the 24 and 34 to the planting portions 25 and 35 are equal to each other in the excavation bit 21 and the protection bit 31.

  Of these, the excavation bit 21 has a mountain shape in which the distal end surface 25a of the planting portion 25 is flat, and the central portion in the longitudinal direction most protrudes from the side surface 24a and is a flat surface parallel to the side surface 24a. In addition, the inclined surface is formed so as to gradually recede from the central portion toward both ends in the longitudinal direction. The distal end surface 25a has a plurality of concave holes parallel to each other and perpendicular to the side surface 24a. It is drilled in a substantially zigzag shape, and is planted by inserting the long excavation tip 23 into these concave holes and brazing. These excavation tips 23 have the same diameter and the same length, and the tip of what is planted on the flat surface protrudes most, and the one planted on the inclined surface has the slope. The tip is set back in steps according to the inclination of the surface.

  Further, in the excavation bit 21 of the present embodiment, a part of the excavation chips 23a (eight in the present embodiment) among the excavation chips 23 planted in the planting portion 25 in this way has a part of the outer peripheral surface thereof. When attached to the cutter ring 11, each is protruded and exposed from the side surface 25 b of the planting portion 25 directed toward the radially inner and outer periphery. However, the protrusion amount P from the side surface 25b of the excavation tip 23a is set to be ½ or less of the diameter d which is the dimension in the radial direction of the excavation tip 23a. In this embodiment, the diameter d is 3 mm. The protrusion amount P is 0.7 mm, which is 1/4 or less.

  On the other hand, the planting portion 35 of the protection bit 31 in the protection bit main body 32 has a front end surface 35a parallel to the side surface 34a of the attachment portion 34, and the protruding height from the side surface 34a is the side surface 24a of the excavation bit 21. The width between both side surfaces 35b directed to the radially inner and outer circumferences of the cutter ring 11 is smaller than the height between the both side surfaces 25b of the planting portion 25 of the excavation bit 21 while being smaller than the projecting height of the planting portion 25 from The width is slightly larger and is equal to the width including the excavation tip 23a exposed from the side surface 25b. In addition, the magnitude | size of the said longitudinal direction of these planting parts 25 and 35 is mutually made equal.

  The planting portion 35 of the protection bit 31 is provided with a large number of zigzag concave holes perpendicular to the side surfaces 35b, and the protective chip 33 is inserted into these recess holes for brazing. Has been planted. Here, these protective tips 33 have the same diameter and the same length as each other, and the drilling tip 23 has the same diameter, but the length thereof is shortened. It is planted to be exposed. Note that the number of protection chips 33 implanted in one protection bit 31 is smaller than that of the excavation bit 21. Further, a sufficient gap is provided between the bottoms of the concave holes drilled in both side surfaces 35b of the planting portion 35.

  The excavation bit 21 and the protection bit 31 have a bit body in which the thickness direction is directed to the radial direction of the cutter ring 11 and the side surfaces 24a and 34a are flush with the front end surface 12 of the cutter ring 11. The attachment portions 24 and 34 of 22 and 32 are inserted into the concave portion 13 and are fixed by welding or the like to be integrated with the cutter ring 11. Accordingly, the protection bit 31 has its tip (tip surface 35a of the planting portion 35) retracted in the direction of the axis O more than the tip of the drill bit 21 (tip of the drilling tip 23 planted on the flat surface of the tip surface 25a). It will be arranged at the position.

  In addition, each bit 21, 31 has a plane passing through the center in the thickness direction of the mounting portions 24, 34 of the bit bodies 22, 32, and the center of the radial thickness of the cutter ring 11 at the center in the longitudinal direction. It arrange | positions so that the cylindrical surface which passes may be contact | connected. Therefore, the excavation bit 21 and the protection bit 31 are arranged such that the excavation tip 23 of the excavation bit 21 is implanted in the planting portion 35 in which the protection chip 33 of the protection bit 31 is implanted in the rotation locus around the axis O. In particular, in this embodiment, the width between the both side surfaces 35b of the planting part 35 and the tip of the protective tip 33 exposed flush with the excavation bit is arranged in the present embodiment. 21 are overlapped so as to coincide with the width between the protruding ends of the excavation tip 23a exposed on both side surfaces 25b of the planting portion 25.

  Furthermore, the number of protection bits 31 smaller than the number of excavation bits 21 is provided at the tip of the cutter ring 11. More specifically, in the present embodiment, as shown in FIG. 1, the three concave portions 13 that are close to each other at equal intervals in the circumferential direction are grouped at the tip of the cutter ring 11, and five concave portions 13 are adjacent to each other. The cutting bits 21 are arranged at equal intervals in the circumferential direction at intervals larger than the intervals, the excavation bits 21 are arranged in the concave portions 13 at both ends of each group, and the protection bits 31 are arranged in the central concave portion 13. The number of the protection bits 31 is 0.5 times the number of the excavation bits 21, that is, half the number of the protection bits 31. The excavation bits 21 and the protection bits 31 have the same shape and size.

  The excavation tool configured as described above is rotated around the axis O and sent to the front end side in the direction of the axis O to excavate the ground of the soft rock layer from the soft layer and continuously to the ground. Used for excavating buried objects such as reinforced concrete, steel or steel and unreinforced concrete, such as shield tunnels in existing sewer mains, and connecting branch holes later to this sewer main Is done. In the excavation tool having the above-described configuration, the excavation bit 21 and the rotation trajectory overlap with the excavation bit 21 that mainly performs such excavation at a position retracted in the axis O direction at the distal end portion of the cutter ring 11. A protection bit 31 is provided, and it is possible to perform reliable and efficient excavation while protecting the excavation bit 21 by this protection bit 31 and preventing the excavation tip 23 from falling off.

  That is, when the cutter ring 11 is rotated around the axis O and sent to the distal end side, the excavation bit 21 protruding toward the distal end side of the protection bit 31 precedes the excavation tip 23 to excavate the ground and the buried object, While forming an annular cross-section groove according to the rotation trajectory of the excavation bit 21, the excavation tip 23 and the planted portion 25 of the excavation bit main body 22 are worn away from the front end face 25 a side. And when these have worn out appropriately, the excavation efficiency is maintained by repeating the process that the excavation tip 23 breaks at the tip side and a new cutting edge is self-generated, thereby recovering the sharpness.

  On the other hand, in the succeeding protection bit 31, the protection chip 33 is exposed on the side surface 35 b facing the inner and outer periphery of the cutter ring 11 in the planting portion 35 of the protection bit body 32, and the rotation locus of the protection bit 31 is excavated. Since these are overlapped with the bit 21, these protective tips 33 come into sliding contact with the inner wall surface of the annular groove formed by the excavation bit 21. Therefore, it is possible to prevent the side surface 25b from slidingly contacting the inner wall surface of the groove, particularly on the rear end side of the planting portion 25 of the excavation bit 21, and thereby the excavation tip 23 can be It is possible to prevent the occurrence of a situation where the normal cutting edge is not self-generated, but breaks or falls off the root, and it is possible to reliably excavate buried objects from the ground as described above. It becomes.

  In particular, in the excavation bit 21 of the above embodiment, a part of the excavation tip 23a in the planting portion 25 of the excavation bit main body 22 is part of the outer peripheral surface from the side surface 25b facing the radially inner and outer periphery of the cutter ring 11. It is planted so as to protrude and be exposed, and this also makes it possible to suppress wear of the side surface 25b. Further, in this case, since the protruding amount P from the side surface 25b of the part of the excavation tips 23a is set to ½ or less of the dimension (diameter d) in the radial direction of the cutter ring 111 of the excavation tips 23a, The exposed part of the excavation tip 23a does not easily fall off.

  In the excavation bit 21 of the present embodiment, this part of the excavation tip 23a has the same long cylindrical shape as the other excavation tips 23. For example, the excavation bit 21 of the above-described embodiment shown in FIG. As in the example, a part of the excavation tips 23a exposed to the side surface 25b, such as a regular quadrangular prism shape, may be a columnar shape or an axial shape different from the other excavation tips 23. However, even in such a case, it is desirable that the protrusion amount P from the side surface 25b of this part of the excavation tip 23a is not more than ½ of the dimension d in the radial direction of the cutter ring 11.

  Further, when the excavation bit 21 is worn from the front end side as described above and the cutting blade 23 is broken while the cutting blade is self-generated, the protection bit main body 32 of the protection bit 31 also has the distal end surface 35a of the planting portion 35. Will come into sliding contact with the bottom surface of the groove formed by the excavation bit 21, and will be worn away from the tip surface 35a. Then, the protective tips 33 planted in the planted portion 35 are also sequentially dropped from the distal end surface 35a side, so that the distal end of the excavating tip 23 protrudes from the distal protective tip 33 in the axis O direction. Since the state is maintained, most of the length can be used up without preventing the self-growth of the cutting blade of the excavation tip 23 as described above.

  Further, the main excavation is performed by the excavation bit 21 as described above, and the protection bit 31 protects the excavation bit 21 from unnecessary wear, whereas the number of the protection bits 31 is excavated in this embodiment. The number is less than the bit 21 and is half of the excavation bit 21. Accordingly, it is possible to prevent a situation in which the excavation resistance increases due to the protective bit 31 being excessively more than necessary and the protective chip 33 being in sliding contact with the wall surface, and more efficient excavation can be promoted. .

  In order to suppress the increase in excavation resistance and promote efficient excavation in this way, the smaller the number of protection bits 31, the better. However, if the number of protection bits 31 is too small, the protection effect by preventing wear of the excavation bit 21 is achieved. However, there is a risk that reliable excavation cannot be performed. Conversely, if the number of protection bits 31 is too large relative to the number of excavation bits 21, the excavation resistance increases as described above, so the number of protection bits 31 is 0.2 times the number of excavation bits 21. It is desirable that the range is about 0.8 times.

  In the present embodiment, the width between both side surfaces 35b of the planting portion 35 of the protection bit 31 where the tip of the protection chip 33 is exposed flush with the side surface 25b of the planting portion 25 of the excavation bit 21 is projected. The excavation tip 23a is exposed to the same width as the protruding ends, and the excavation bit 21 and the protection bit 31 are disposed with their centers in the thickness direction being located at the center of the thickness of the cutter ring 11. Therefore, the planting portions 25 and 35 are overlapped so that their rotational loci coincide with each other in the radial direction with respect to the axis O including the tips 23a and 33. For this reason, the protection tip 33 can be slidably contacted with the inner wall surface of the groove formed by the excavation bit 21 to protect the excavation bit 21.

  However, even if the protective tip 33 does not necessarily coincide with the planting portion 25 of the excavation bit 21 in the radial direction in this rotation locus, for example, as shown in FIG. 2, the diameter of the cutter ring 11 with respect to the axis O If it is the range A of about 2 mm in the inner and outer circumferences in the direction, it may protrude or reverse. That is, if the protective tip 33 protrudes from the rotation trajectory of the excavation bit body 22 of the excavation bit 21 larger than this, the excavation amount by the protective tip 33 increases and the resistance increases, but the protective tip 33 further increases. If the head is retracted greatly, the protection effect of the cutting bit 21 by the protection tip 33 may be insufficient.

  Furthermore, if the retraction amount B from the tip of the excavation bit 21 to the tip of the protection bit 31 in the direction of the axis O shown in FIG. 3 is too large, the excavation bit body on the tip side of the planting portion 25 of the excavation bit 21 Therefore, the wear of the excavation tip 23 at the beginning of excavation becomes large, which may impair the life extension. On the other hand, if the retraction amount B is too small, it is formed by the excavation bit 21 depending on the relationship between the rotational speed and the feed speed of the cutter ring 11 and the distance between the excavation bit 21 and the protection bit 31 in the circumferential direction. There is a possibility that the protective bit 31 is brought into sliding contact with the bottom surface of the groove at an early stage and the wear thereof is promoted too much. For this reason, the tip of the protection bit 31 is 0.2 × H to 0.8 × with respect to the protrusion height H from the tip surface 12 of the cutter ring 11 to the tip of the excavation bit 21 as shown in FIG. It is desirable to recede from the tip of the excavation bit 21 in the range of H.

  On the other hand, the tip of the protection bit 31 is the length from the tip of the excavation bit 21 to the rearmost end of the excavation tip 23 planted in the planting portion 25 of the excavation bit body 22 in the axis O direction as shown in FIG. That is, for the effective length L of the excavation tip 23, the height C from the rearmost end of the excavation tip 23 to the front end of the protection bit 31 in the axis O direction is 0.2 × L to 0.8 ×. The range of L is desirable. That is, if the height C from the rear end of the excavation tip 23 to the tip of the protection bit 31 is too small with respect to the effective length L of the excavation tip 23, the excavation bit main body 22 is also worn at the front end side of the excavation bit 21. On the contrary, if the height C is as large as the effective length L, the wear of the tip of the protection bit 31 is promoted to cause the protection tip 33 to fall off, and the excavation resistance increases. It will also be.

  In this embodiment, the protection bit body 32 of each protection bit 31 is implanted so that the protection chip 33 is exposed on both side surfaces 35b of the planting portion 35, and is exposed on these both side surfaces 35b. The interval between the protective tips 33, that is, the width of the planting part 35 is made to coincide with the width of the excavation bit 21 in the rotation trajectory around the axis O, but the diameter of the planting part 35 is the protective bit 31. There are two types: one planted so that the protective tip 33 is exposed only on the side facing the inner circumferential side, and one planted so that the protective chip 33 is exposed only on the side facing the outer radial side These may be arranged so that they overlap the excavation bit 21 in the rotation locus around the axis O.

  In this case, the protective tip 33 is located on either side of the inner and outer peripheries of the cutter ring 11 on both sides 25b of the planting portion 25 of the excavation bit body 22 on either side where the protective tip 33 is exposed. It is only necessary that the rotation trajectory protrudes or retracts in the range A up to the above 2 mm with respect to the one facing the same side. In this case, the planting portion 35 of the protection bit 31 in the protection bit main body 32 may be formed so as to be biased only to the side surface 35b side where the protection chip 33 is exposed.

  Similarly, the excavation bit main body 22 of the excavation bit 21 also has a width of the planting portion 25 equal to the excavation width, that is, the width of the groove in the present embodiment. For example, two kinds of excavation bits having planting portions 25 biased toward the inner and outer circumferences so as to divide the excavation width into two in the radial direction are alternately arranged in the circumferential direction. Or even with the same excavation bit, the excavation bits around the axis O of the excavation tip can be arranged alternately on the inner peripheral side and the outer peripheral side of the tip end portion of the cutter ring 11. It is also possible to perform excavation so as to form a groove having the excavation width by overlapping the rotation trajectories.

It is the front view seen from the axis line O direction tip side showing one embodiment of the excavation tool of the present invention. FIG. 2 is an enlarged front view showing a group of excavation bits 21 and protection bits 31 in the embodiment shown in FIG. 1. It is an enlarged side view which shows the excavation bit 21 and the protection bit 31 at the front-end | tip of the cutter ring 11 in embodiment shown in FIG. It is a perspective view which shows the excavation bit 21 of one Embodiment of this invention arrange | positioned by embodiment shown in FIG. It is a front view of embodiment shown in FIG. FIG. 6 is a side view of the embodiment shown in FIG. 5. It is a side view of the arrow X direction view in FIG. It is YY sectional drawing in FIG. It is a front view of the protection bit 31 arrange | positioned in embodiment shown in FIG. FIG. 10 is a side view of the protection bit 31 shown in FIG. 9. It is a side view of the arrow X direction view in FIG. It is a front view which shows the modification of the excavation bit 21 of one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Cuttering 12 The front end surface of the cutter ring 11 21 Excavation bit 22 Excavation bit main body 23 Excavation tip 24 The attachment part of the excavation bit main body 22 The planting part 25a of the excavation bit main body 22 The front end surface 25b of the planting part 25 Side surface of planting portion 25 facing radially inner and outer periphery 31 Protection bit 32 Protection bit body 33 Protection chip 34 Mounting portion of protection bit body 32 35 Planting portion of protection bit body 32 35a Tip surface 35b of protection portion 35 Cuttering 11 Side surface of the planting portion 35 facing the radially inner and outer circumference of the O O axis of the cutter ring 11 A The end of the protective tip 33 exposed on at least one of the radially inner and outer circumferential surfaces of the protective bit 31 is in the rotation locus around the axis O. Range in which the drill bit body 22 protrudes or retracts from the inner and outer peripheral surfaces on the same side in the radial direction H Cuttering 11 Projection height from the front end surface 12 of the excavation bit 21 to the front end of the excavation bit 21 B Backward amount from the front end of the excavation bit 21 to the front end of the protection bit 31 in the direction of the axis O L Main body of the excavation bit in the direction of the axis O from the end of the excavation bit 21 22 to the end of the excavation tip 23 planted in 22 (effective length of the excavation tip 23)
C Height from the rearmost end of the excavation tip 23 to the front end of the protection bit 31 in the direction of the axis O P A protruding amount of a part of the exposed excavation tip 23 from the radially inner and outer peripheral surface (side surface 25b) of the excavation bit body 22 d Outer diameter of excavation tip 23 (dimension in radial direction with respect to axis O of excavation tip 23)

Claims (7)

  A drilling bit planted so that a drilling tip harder than the drilling bit body protrudes from the tip of the drilling bit body at the tip of the cutter ring rotated about the axis, and harder than the protection bit body And a protection bit planted so that the protection chip is exposed on at least one of the radially inner and outer peripheral surfaces of the protection bit body with respect to the axis, the tip of the protection bit being more than the tip of the excavation bit An excavation tool, wherein the excavation tool is disposed at a position retracted in the axial direction so that a rotation locus around the axial line overlaps the excavation bit.   The excavation tool according to claim 1, wherein the protective bit is provided at a tip portion of the cutter ring in a number of 0.2 to 0.8 times the number of the excavation bits.   The end portion of the protective tip exposed on at least one of the radially inner and outer peripheral surfaces of the protective bit protrudes up to 2 mm with respect to the inner and outer peripheral surfaces on the same side in the radial direction of the excavation bit body in the rotation locus. The excavation tool according to claim 1, wherein the excavation tool is retracted.   With respect to the protrusion height H from the tip surface of the cutter ring to the tip of the excavation bit, the tip of the protection bit is 0.2 × H to 0.8 × H from the tip of the excavation bit in the axial direction. The excavation tool according to any one of claims 1 to 3, wherein the excavation tool is retracted in a range.   The protection in the axial direction from the rearmost end of the excavation tip against the effective length L of the excavation tip from the distal end of the excavation bit to the rearmost end of the excavation tip implanted in the main body of the excavation bit in the axial direction. The height to the front-end | tip of a bit is made into the range of 0.2 * L-0.8 * L, The excavation tool as described in any one of Claims 1-4 characterized by the above-mentioned.   A drilling bit provided in the drilling tool according to any one of claims 1 to 5, wherein at least one of the radially inner and outer peripheral surfaces with respect to the axis of the drilling bit body is provided with one of the drilling tips. A drill bit characterized in that the part is exposed.   The amount of protrusion of the exposed excavation tip from at least one of the radially inner and outer peripheral surfaces of the excavation bit body is set to be ½ or less of the radial dimension of the excavation tip with respect to the axis. The excavation bit according to claim 6.

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