JP2017218743A - Drilling tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress direct exertion of an impact from striking force applied on a tool body on a member fixed by preventing fall-off of an engaging pin.SOLUTION: A drilling tool includes a tool body 1 with a fitting hole part 2, and a fitting member 5 having a fitting shaft part 4 to be inserted into the fitting hole part 2 and fitted detachably to the tool body 1. A recessed groove is formed on an outer peripheral surface of the fitting shaft part 4, along a plane A orthogonal to a center line L2 of the fitting shaft part 4. A pin hole 8 is formed on the tool body 1, the pin hole extending from an outer surface of the tool body 1 along the plane A of the fitting shaft part 4 inserted into the fitting hole part 2, the pin hole opening partially on an inner peripheral surface of the fitting hole part 2. An engaging pin 9 inserted into the pin hole 8 is engaged with the recessed groove of the fitting shaft part 4 inserted into the fitting hole part 2. At least a part of an opening part of the pin hole 8 on the outer surface of the tool body 1 may be covered by a cover member 10 fitted detachably on the tool body 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drilling tool such as a diameter expanding bit having a tool body provided with a mounting hole, and a mounting member having a mounting shaft inserted into the mounting hole and detachably attached to the tool body. It is about.

  As such an excavation tool, a mounting hole is opened at a position eccentric from the axis of the tip of the tool body (device) rotated about the axis, and the mounting shaft is inserted into the mounting hole. A so-called diameter expansion bit or an underreaming bit is known in which an excavation part provided with an excavation tip is provided at the tip of a mounting member (bit head) detachably attached to the main body. Yes. With such a diameter expanding bit, the mounting member rotates around the center line of the mounting shaft portion as the tool body rotates, and the radius from the axis line of the excavation portion expands and contracts. In addition to forming a hole, the inside of the casing pipe inserted into the excavation hole can be pulled out and collected in a reduced state.

  For example, a drilling tool described in Patent Document 1 is used to insert the attachment shaft portion into the attachment hole portion and attach the attachment member to the tool body so as to be detachable and rotatable about the center line of the attachment shaft portion. In the outer peripheral surface of the mounting shaft portion, a concave groove intersecting with the extending direction of the mounting shaft portion is formed, and the tool body extends in a direction intersecting with the extending direction of the mounting hole portion, and a part thereof is the mounting hole portion. A pin hole penetrating the shaft is formed, and a locking pin that engages with the groove of the mounting shaft portion is inserted into the pin hole. The concave groove is formed in an L shape when viewed in the direction of the rotation axis of the mounting shaft portion, and the mounting member engages with a locking pin within the range of the L shape formed by the concave groove and can be freely rotated. In addition, it is possible to remove the locking pin from the tool body by extracting it from the pin hole.

  In addition, in Patent Document 1, as a means for fixing the locking pin to the pin hole and preventing it from being removed other than when the attachment member is removed, the pin hole opening is made of a rigid body and is attached to the end surface of the locking pin. It has been proposed to provide a disk-shaped fixing member that contacts and fixes the locking pin, and a locking portion that locks and fixes the fixing member in the extending direction of the pin hole. Further, this Patent Document 1 also proposes disposing a disk-shaped auxiliary member, which is made of an elastic body such as synthetic rubber, and maintains the locked state between the fixing member and the locking portion in the tool body. Has been.

  Here, a slide groove in which the fixing member is slid and moved is formed in the tool body so as to extend in the axial direction of the tool body. The pin hole is opened at one end of the slide groove, and the locking portion is formed. Has been. In addition, the other end of the slide groove is provided with a fixing member insertion portion, and the fixing member inserted from the insertion portion is slid to one end of the slide groove and locked to the locking portion. Thereafter, the auxiliary member is attached to the insertion portion and presses the fixing member, so that the movement of the fixing member is prevented and the locking state between the fixing member and the locking portion is maintained.

Japanese Patent No. 4957440

  By the way, when the excavation hole is formed by the excavation tool such as the above-described diameter expansion bit, the thrust toward the distal end side in the axial direction and the rotational end force that rotates the tool body around the axial line, and the distal end in the axial direction are also the same. A striking force directed toward the side is applied to the tool body. And when this striking force is transmitted exclusively to the attachment member attached to the front-end | tip part of a tool main body, excavation advances by crushing a rock etc. with the said excavation tip.

  However, since the fixing member and the auxiliary member are directly attached to the tool body, it is inevitable that the impact due to the striking force on the tool body is directly transmitted to the fixing member and the holding member. For this reason, the fixing member and the auxiliary member are worn by impact and loosen between the locking portion and the insertion portion, and the looseness due to the impact further increases with this loosening, and finally. May cause damage to the fixing member and the auxiliary member, and the locking pin may not be fixed.

  The present invention is made under such a background, it is possible to suppress the impact due to the impact force applied to the tool body to directly act on the member that prevents and fixes the locking pin, An object of the present invention is to provide an excavation tool capable of fixing a locking pin stably over a long period of time.

  In order to solve the above problems and achieve the above-described object, the present invention provides a tool body provided with a mounting hole and a mounting shaft portion inserted into the mounting hole. An excavation tool having a mounting member that is detachably mounted, wherein an outer peripheral surface of the mounting shaft portion is formed with a concave groove along a plane orthogonal to the center line of the mounting shaft portion, and The tool main body is formed with a pin hole extending from the outer surface of the tool main body along the plane of the mounting shaft portion inserted into the mounting hole portion and partially opening to the inner peripheral surface of the mounting hole portion. The locking pin inserted into the pin hole is locked in the concave groove of the mounting shaft portion inserted into the mounting hole, and the opening of the pin hole on the outer surface of the tool body is At least a part of the cover member is detachably attached to the tool body. Characterized in that it is capable coating Te.

  In the excavation tool configured in this way, at least a part of the opening of the pin hole of the tool main body into which the locking pin for locking the mounting member is inserted is covered with a cover member that is a separate member from the tool main body. In this way, by covering at least a part of the opening of the pin hole with the cover member, the locking pin can be prevented from coming off and fixed by the cover member. Since such a cover member can avoid the direct impact of the impact force applied to the tool body, it can prevent loosening, rattling and breakage due to wear, and can be used for a long time. Thus, the attachment member can be stably attached to the attachment hole.

  Here, as in the excavation tool described in Patent Document 1, the outer surface of the tool body in which the pin hole opens is formed in a cylindrical surface centered on an axis parallel to the center line of the mounting hole. In this case, the cover member is preferably formed in a cylindrical shape having an inner peripheral surface facing the outer surface. However, in such a case, the cover member may be integrally formed in a cylindrical shape from the beginning. However, the cover member is divided into a plurality of divided bodies in the circumferential direction. It may be formed in a shape.

  In particular, when the cover member is formed in a cylindrical shape as described above, a through hole is formed in the cover member at a position where it can communicate with the opening of the pin hole. By attaching a sealing member that seals the hole, it is possible to easily prevent the locking pin from coming off by displacing the cover member after inserting the locking pin into the pin hole through the through hole. A situation in which the generated dusting powder enters the through hole and wears the locking pin can be prevented by the sealing member.

  Therefore, such a configuration is a device in which the tool body is rotated about an axis, the attachment hole portion is opened at a position eccentric from the axis line of the tip portion of the tool body, and the pin hole is An opening is formed on the outer peripheral surface of the outer cylindrical cover mounting portion centering on the axis formed at the front end portion of the tool body, and the rear end side of the tool body is closer to the outer peripheral side than the pin hole. A step portion that expands in diameter is formed, the cover member is formed in a cylindrical shape, and the rear end surface is fitted into the outer periphery of the cover mounting portion in contact with the step portion, and the pin hole is opened. The mounting member is a bit head in which a drilling portion in which a drilling tip is disposed is provided at a tip of the mounting shaft portion, and the tool body is rotated with the rotation of the tool body. The radius from the above axis of the excavated part is the diameter In the case of applying the drilling tool rotates about line around the mounting shaft portion so that, since the attachment member as described above can be mounted stably, it is preferable.

  Furthermore, in such an excavation tool, a cylindrical casing top attached to the tip end portion of the casing pipe is disposed on the outer periphery of the tip end portion of the tool main body, and the inner diameter of the casing top is defined by the tool main body. When the casing pipe is inserted into the excavation hole while the excavation hole is formed by the striking force and thrust applied to the tool body, the outer diameter of the stepped portion on the rear end side of the tip end The excavation is performed by disposing the cover member between the inner peripheral surface of the casing top and the outer peripheral surface of the cover mounting portion by making the outer diameter of the cover member smaller than the inner diameter of the casing top. Therefore, when the through-hole is formed in the cover member and the sealing member is attached as described above, the dusting powder enters the gap between the sealing member and the casing top. It can also prevent a situation such as occurs with.

  As described above, according to the present invention, it is possible to prevent the impact due to the striking force applied to the tool body from directly acting on the cover member, so that the cover member that prevents the locking pin from coming off and is fixed. It is possible to prevent looseness, rattling and breakage due to wear of the metal, and to stably attach the mounting member to the mounting hole over a long period of time.

It is side sectional drawing of the tool main body front-end | tip part which shows one Embodiment of this invention. FIG. 2 is a front view showing a state in which a mounting member (bit head) has an enlarged diameter in the embodiment shown in FIG. 1 (however, the casing pipe and the casing top are not shown). FIG. 2 is a front view showing a state in which the diameter of a mounting member (bit head) is reduced in the embodiment shown in FIG. 1 (however, the casing pipe and the casing top are not shown). It is the (a) front view and (b) side view of the attachment member (bit head) of embodiment shown in FIG. It is sectional drawing along the plane A in FIG. 1 of the tool main body and attachment member of embodiment shown in FIG. (A) sectional side view of cover member of embodiment shown in FIG. 1, (b) ZZ sectional view in FIG. (A), (c) Plane view in arrow Y direction in FIG. FIG. It is a sectional side view of the tool main body in the state where the cover member is not attached, showing the assembly order of the embodiment shown in FIG. It is a sectional side view which shows the state which covered the cover member on the tool main body front-end | tip part of the state shown in FIG. FIG. 9 is a side cross-sectional view showing a state in which an attachment member is disposed by inserting an attachment shaft portion into an attachment hole at the tip of the tool body in the state shown in FIG. 8. FIG. 10 is a side sectional view showing a state in which a locking pin is inserted into the pin hole of the tool body in the state shown in FIG. 9. FIG. 10A is a side sectional view showing a state where the sealing member and the auxiliary member are attached to the through hole of the cover member in the state shown in FIG. 10 and the locking pin is fixed, and FIG. It is a top view of arrow line X direction view. It is a sectional side view which shows the state which inserts the tool main body of the state shown in FIG. 11 in a casing pipe. It is a sectional side view which shows the state which made the tool main body front-end | tip part of the state shown in FIG. 12 protrude from a casing top, and expanded the excavation part of the attachment member.

  1 to 13 show an embodiment of the present invention, and this embodiment is a case where the present invention is applied to the above-described expanded bit. In the present embodiment, the tool body 1 is a device of such a diameter-expanding bit, and has a substantially multi-stage cylindrical shape with the axis O as the center, and its rear end (FIGS. 1, 6 to 6). 13 is the smallest diameter shank portion 1A.

  Such an excavating tool is given a striking force to the tool body 1 in the direction of the axis O (left side in FIGS. 1 and 6 to 13) by a down-the-hole hammer (not shown) connected to the shank portion 1A. The excavator connected to this down-the-hole hammer via an excavating rod gives a rotational force around the axis O in the tool rotation direction T and a thrust toward the tip side in the axis O direction, excavating the ground (bedrock) etc. Form holes.

  A first step portion 1B having the largest outer diameter is formed on the tip end side of the shank portion 1A of the tool body 1, and a step diameter smaller than that of the first step portion 1B is formed on the tip end side of the first step portion 1B. A second step portion 1C having an outer diameter as a step portion in the present embodiment is formed, and the tip portion of the tool body 1 on the tip side of the second step portion 1C further has a constant outer diameter that is one step smaller. The cover mounting portion 1D is formed in a cylindrical shape. Further, the length of the tip portion of the tool body 1 in the axis O direction is the longest in the cover mounting portion 1D, the longest first step portion 1B, and the shortest second step portion 1C.

  Further, on the outer periphery of the tool body 1, a cylindrical casing pipe P centering on an axis O having an inner diameter slightly larger than the outer diameter of the first step portion 1B is disposed. A multi-stage cylindrical casing top Q having an inner diameter that is smaller than the outer diameter of the first step portion 1B and slightly larger than the outer diameter of the second step portion 1C is provided at the tip, and the rear end thereof is the tip of the casing pipe P. It is joined and attached in a state of being fitted to the inner periphery of the part. The first step portion 1B comes into contact with the rear end surface of the casing top Q attached in this manner and the thrust and striking force toward the front end side in the axis O direction are transmitted, so that the casing pipe P is inserted into the excavation hole formed by the excavation tool. It will be inserted.

  The front end surface of the tool body 1 is a flat surface perpendicular to the axis O, and the first step portion 1B is in contact with the rear end of the casing top Q as described above. It arrange | positions so that it may be located in. Further, on the outer periphery of the tip of the tool body 1 from the tip surface to the rear end of the first step portion 1B, three discharge grooves 1E for discharging excavation waste generated during excavation are formed at equal intervals in the circumferential direction. Has been. The bottom surfaces of the discharge grooves 1E facing the outer peripheral side are inclined so as to be separated from the axis O as they go from the front end surface to the rear end side of the tool body 1, and then extend in parallel to the axis O to extend to the first step portion 1B. It has reached the rear end.

  Further, on the front end surface of the tool body 1, three mounting hole portions 2 extending from the front end surface toward the rear end side are formed at equal intervals in the circumferential direction between the discharge grooves 1E in the circumferential direction. These mounting holes 2 are formed in a circular cross section having a constant inner diameter centered on a hole center line L1 that is parallel to the axis O and eccentric from the axis O to the outer peripheral side. A blow hole 3 is formed from the rear end of the tool body 1 along the axis O to eject compressed air or the like during excavation. , The inclined bottom surface of the discharge groove 1E, the outer peripheral surface of the second step portion 1C, and the bottom surface of the mounting hole portion 2.

  The mounting member 5 in which the mounting shaft portion 4 is inserted into the mounting hole portion 2 and is detachably mounted on the tool body 1 is the bit head of the diameter-expanding bit in the present embodiment, and the mounting shaft portion 4 The excavation part 6 is integrally formed in the front-end | tip. A large number of excavation tips 7 made of cemented carbide or the like having a hardness higher than that of the tool body 1 and the mounting member 5 made of steel or the like are embedded in the front end surface and the outer peripheral surface of the excavation portion 6. The ground is crushed by the excavation tip 7 and excavation is performed.

  The mounting shaft portion 4 has a cylindrical shaft shape with the shaft portion center line L2 as the center, and is formed such that its outer diameter is slightly smaller than the inner diameter of the mounting hole portion 2, and its length is the mounting length. It is formed so as to be substantially equal to the depth of the hole 2. Accordingly, the mounting shaft portion 4 is slidably fitted into the mounting hole portion 2 so that the shaft portion center line L2 is inserted coaxially with the hole portion center line L1, and the rear end surface thereof is in contact with the bottom surface of the mounting hole portion 2. By the way, the rear end face of the excavation part 6 comes into contact with the front end face of the tool body 1, and thus the attachment member 5 rotates around the hole center line L1 in the inserted state in which the attachment shaft part 4 is inserted into the attachment hole part 2. It is made free.

  As shown in FIGS. 2, 3 and 4A, the excavation part 6 has a generally fan shape in a front end view, that is, two side surfaces intersecting each other at an obtuse angle of 120 ° and both ends of these side surfaces. It has a convex arc surface shape to be connected or a convex side surface in which a convex arc surface and a plane are combined. The two side surfaces are in a planar shape parallel to the shaft center line L2, and one is a long side surface (long side surface) and the other is a short side surface (short side surface) in the front end view. The portion is slightly inclined so as to go toward the shaft centerline L2 as it goes toward the rear end.

  When the mounting member 5 is rotated around the shaft center line L2 in the opposite direction to the tool rotation direction T, the excavation unit 6 has a configuration in which the mounting members 5 adjacent to each other in the circumferential direction as illustrated in FIG. The short side surface of one excavation portion 6 is positioned in contact with the short side surface portion of the long side surface of the excavation portion 6 of the mounting member 5 adjacent to the side opposite to the tool rotation direction T. At this time, the portion connected to the long side surface of the convex side surface is larger than the outer diameter of the casing pipe P or the casing top Q and protrudes to the outer peripheral side of the tool body 1 to expand the diameter, and an arc centered on the axis O in the front end view. It is arranged to make.

  Further, when the mounting member 5 is rotated in the tool rotation direction T around the shaft centerline L2, the short side surface of one excavation unit 6 between the mounting members 5 adjacent to each other in the circumferential direction as shown in FIG. However, the diameter is reduced by abutting and positioning the portion of the long side surface of the excavating portion 6 of the mounting member 5 adjacent to the side opposite to the tool rotation direction T on the convex side surface side. In this reduced diameter state, the portion of the convex side surface that is farthest from the axis O is smaller than the inner diameter of the casing top Q and slightly smaller than the outer diameter of the second step portion 1C. It arrange | positions so that it may be located on the cylindrical surface centering on the axis line O of a diameter larger than a diameter.

  Further, the outer peripheral surface of the mounting shaft portion 4 of the mounting member 5 is recessed along a plane A orthogonal to the shaft centerline L2, that is, a plane A orthogonal to the hole centerline L1 in the inserted state. A groove 4A is formed. In this embodiment, the concave groove 4A is an annular groove that goes around the outer periphery of the mounting shaft portion 4 around the shaft portion center line L2 as shown in FIGS. 4B and 5. In the cross section along the line L2, it is formed in a half-oval shape extending in the direction of the axial center line L2. The concave groove 4A is formed on the long side surface side of the excavation part 6 when viewed from the direction of the shaft centerline L2, for example, instead of forming such an annular groove, and is perpendicular to the shaft centerline L2. The cross section along the plane A is formed in an L shape that is bent at approximately 120 °. However, the bent portion is a convex circle centered on the axial center line L2 that is in contact with the linearly extending portions on both sides thereof. It may be formed in an arc shape.

  On the other hand, a bottomed pin hole 8 is formed in the tool body 1 along the plane A that is orthogonal to the hole center line L1 in the inserted state. In this embodiment, the pin hole 8 has a circular cross section. The pin hole 8 is in contact with the inner peripheral surface of each of the three mounting hole portions 2 from the opposite side of the tool rotation direction T, and a tangent line orthogonal to the axis O is defined as the pin hole center. It extends as a line C and is formed so as to open on the outer peripheral surface of the cover mounting portion 1D which is the outer surface of the tool body 1. Accordingly, these pin holes 8 are portions where the pin hole center line C is in contact with the inner peripheral surface of the mounting hole portion 2 and are partially opened on the inner peripheral surface of the mounting hole portion 2.

  The radius of the pin hole 8 is substantially equal to the depth from the outer peripheral surface of the mounting shaft portion 4 to the groove bottom of the recessed groove 4A. Further, a cylindrical shaft-like locking pin 9 having an outer diameter slightly smaller than the inner diameter of the pin hole 8 is inserted into the pin hole 8 from the outer peripheral side of the cover mounting portion 1D, as shown in FIG. The part that is partially opened on the inner peripheral surface of the attachment hole 2 is engaged with the concave groove 4A in the attachment shaft part 4 of the attachment member 5, and is brought into contact with the bottom surface of the pin hole 8 on the axis O side of the tool body 1. It has been. When the locking pin 9 contacts the bottom surface of the pin hole 8 in this way, the end surface of the locking pin 9 on the outer peripheral side of the tool body 1 is flush with the outer peripheral surface of the cover mounting portion 1D. Is formed.

  A cover member 10 is placed on the outer peripheral surface of the cover mounting portion 1D, which is the outer surface of the tool body 1, and at least a part of the opening of the pin hole 8 can be covered by the cover member 10. . The cover member 10 of the present embodiment is integrally formed in a cylindrical shape with the axis O as the center, as shown in FIG. 6, by a steel material or the like, like the tool body 1 and the like, and its inner diameter is large enough to fit into the cover mounting portion 1D. In addition, the outer diameter is substantially equal to the outer diameter of the second step portion 1C, and is set slightly smaller than the inner diameter of the casing top Q.

  The length of the cover member 10 in the direction of the axis O is slightly shorter than the length of the cover mounting portion 1D. A second step portion 1C having a larger outer diameter than the cover mounting portion 1D is formed on the rear end side of the cover mounting portion 1D, and the cover is attached even if the diameter is reduced with the mounting member 5 mounted on the front end side. Since the excavation part 6 having an outer diameter larger than that of the attachment part 1D is provided, the cover member 10 is fitted in the cover attachment part 1D within the range of the length difference from the cover attachment part 1D. It is possible to advance and retreat in the direction.

  Further, the cover member 10 includes an opening portion of the pin hole 8 in the direction of the axis O in a state where the front end surface of the cover member 10 is flush with the front end surface of the tool body 1 as shown in FIGS. In the overlapping position, three through holes 11 having a circular cross section are formed at equal intervals in the circumferential direction. Further, a sealing member 12 that seals the through hole 11 in a state where the locking pin 9 is inserted into the pin hole 8 is attached to the through holes 11. Further, a recess 13 is formed on the outer peripheral surface of the cover member 10 so as to communicate with each through hole 11, and a fixing member 14 for fixing the sealing member 12 is disposed in the recess 13. Has been.

  The through hole 11 is formed so that the center line thereof is coaxial with the pin hole center line C in a state where the front end surface of the cover member 10 is in contact with the rear end surface of the excavation part 6 as shown in FIGS. The diameter of the opening on the inner and outer peripheral surfaces of the cover member 10 is set equal to the diameter of the pin hole 8. Further, in this embodiment, as shown in FIGS. 1 and 6, the recess 13 is formed so as to communicate with the rear end side in the axis O direction of the outer peripheral side opening of the through hole 11, but the cover member 10 is provided. It does not penetrate through the inner peripheral surface.

  Further, the recess 13 is positioned on the rear end side of the extension portion 13A extending to the rear end side of the tool body 1 with a width equal to the diameter of the circle formed by the outer peripheral side opening of the through hole 11 and the extension portion 13A. And a circular portion 13B having a larger diameter than the through-hole 11 having a center line parallel to the center line of the through-hole 11. The distance between the center line of the circular portion 13B and the center line of the through hole 11 is set slightly larger than the sum of the radius of the circular portion 13B and the radius of the outer peripheral side opening of the through hole 11.

  Further, a groove is formed in the inner peripheral portion of the through hole 11 and the recess 13 with a slight space between the inner peripheral surface of the cover member 10 and the inner peripheral portion of the through hole 11 among them. The groove formed in the upper portion is a locking portion 11 </ b> A for locking the sealing member 12. Further, a groove formed in the inner periphery of the circular portion 13B in the recess 13 is a locking portion 13C of the fixing member 14, and a groove formed in the extending portion 13A is a slide groove 13D.

  The locking portions 11A, 13C and the slide groove 13D are formed along one plane perpendicular to the pin hole center line C, that is, two groove wall surfaces facing each other in the direction of the pin hole center line C. Are formed flush with each other between the locking portions 11A and 13C and the slide groove 13D. Furthermore, these two groove wall surfaces are formed so as to extend perpendicularly to the pin hole center line C, and the groove bottom surface facing the inner peripheral side of the through hole 11 and the recess 13 between these groove wall surfaces is the groove wall surface. The locking portions 11A, 13C and the slide groove 13D are formed in a rectangular shape in cross section along the pin hole center line C.

  The depth of the groove formed by the locking portions 11A and 13C and the slide groove 13D, that is, the depth from the inner periphery of the through hole 11 and the extended portion 13A of the recess 13 and the circular portion 13B to the groove bottom surface is as follows. The locking portion 11A and the slide groove 13D are formed to have a constant depth that is equal to each other. In contrast, the locking portion 13C of the recess 13 is formed to have a constant groove depth that is shallower than the groove depths of the locking portion 11A and the slide groove 13D.

  Among these, the sealing member 12 attached to the locking portion 11A of the through hole 11 is integrally formed in a disk shape having a two-stage outer diameter by a rigid body such as steel like the tool body 1 and the attachment member 5. Of these, the portion having the larger outer diameter is formed in a size that can be fitted into the engaging portion 11A of the through hole 11 through the slide groove 13D. Further, the portion where the outer diameter of the sealing member 12 is small is formed in a size that can be fitted into the opening of the through hole 11 on the outer peripheral surface of the cover member 10.

  On the other hand, the fixing member 14 disposed in the recess 13 is integrally formed in a disk shape having an outer diameter of two steps by an elastic body such as a synthetic rubber such as urethane rubber. Of these, the outer diameter is large. The diameter portion can be fitted into the locking portion 13C of the recess 13 while being elastically deformed so as to be slightly reduced in diameter, and the small diameter portion can be inserted into the recess 13 on the outer peripheral surface of the cover member 10. The size is such that it can be fitted into the opening. Furthermore, the large-diameter portion is elastically deformed to the outer periphery of the large-diameter portion of the sealing member 12 fitted in the locking portion 11A as described above in a state where the large-diameter portion is fitted in the locking portion 13C. It is the size that can be adhered.

  Next, the case of assembling such an excavation tool will be described with reference to FIGS. First, from the state shown in FIG. 7, as shown in FIG. 8, the cover member 10 is fitted into the cover mounting portion 1 </ b> D at the tip of the tool body 1, and the tip surface of the cover member 10 is flush with the tip surface of the tool body 1. In addition, the cover member 10 is arranged so that the through hole 11 is coaxial with the pin hole 8. Next, as shown in FIG. 9, the attachment shaft portion 4 is inserted into the attachment hole portion 2, and the attachment member 5 is disposed at the distal end portion of the tool body 1. At this time, each attachment member 5 is in a state in which the excavation portion 6 is reduced in diameter.

  Further, the front end surface of the cover member 10 and the tool main body 1 are arranged flush with each other, and the through hole 11 of the cover member 10 is coaxial with the pin hole 8 and disposed at a position where it can communicate. As shown in FIG. 10, the locking pin 9 is inserted into the pin hole 8 from the outer peripheral side of the tool body 1 through the through hole 11, and is locked in the concave groove 4 </ b> A of the mounting shaft portion 4. Next, as shown in FIG. 11, the sealing member 12 is inserted into the recess 13 from the outer periphery of the cover member 10, positioned at the opening of the through hole 11 along the slide groove 13 </ b> D, and locked by the locking portion 11 </ b> A. Further, the sealing member 12 is fixed by locking the fixing member 14 to the locking portion 13 </ b> C of the recess 13.

  When the locking pin 9, the sealing member 12, and the fixing member 14 are attached in this way, the tool body 1 is inserted from the rear end side of the casing pipe P while the attachment member 5 is reduced in diameter as shown in FIG. As shown in FIG. 13, the mounting member 5, the cover mounting portion 1 </ b> D, and the front end portion of the cover member 10 are projected to the front end through the inner periphery of the casing top Q, and the first step portion 1 </ b> B is in contact with the rear end surface of the casing top Q. Let

  Then, when the cover member 10 is shifted to the rear end side and the rear end face is brought into contact with the second step portion 1C, the opening of the pin hole 8 is located on the front end side as shown in FIGS. Since the portion is covered with the cover member 10, the locking pin 9 inserted into the pin hole 8 is prevented from being detached by the cover member 10 and fixed. In addition, after inserting the locking pin 9 into the pin hole 8, the cover member 10 may be shifted at any timing to contact the second step portion 1C. Further, the first step portion 1B of the tool body 1 is brought into contact with the rear end surface of the casing top Q, and the cover member 10 is penetrated with the rear end surface of the cover member 10 in contact with the second step portion 1C. The hole 11 and the pin hole 8 of the tool main body 1 are arranged so as to be located on the rear end side with respect to the front end surface of the casing top Q in the axis O direction.

  When the excavation tool assembled in this way is subjected to excavation by applying a striking force and a thrust force toward the front end side in the axis O direction and a rotational force in the tool rotation direction T, as shown in FIGS. Since the attachment member 5 (bit head) is rotated to the opposite side to the tool rotation direction T by the reaction force due to the rotational force, the diameter of the excavation part 6 becomes larger and the outer diameter of the excavation part 6 becomes larger than the casing pipe P. Excavation can be performed while inserting the casing pipe P into the excavation hole formed by the above.

  In addition, after excavation is completed by forming the excavation hole to a predetermined depth and inserting the casing pipe P, the tool main body 1 is rotated in the direction opposite to the tool rotation direction T, and the reaction force The attachment member 5 rotates in the tool rotation direction T and the diameter of the excavation part 6 is reduced as shown in FIG. 3, so that the tool body 1 can be pulled out and collected while the casing pipe P remains in the excavation hole.

  Thus, in the excavation tool having the above-described configuration, at least a part of the opening of the pin hole 8 of the tool body 1 into which the locking pin 9 is inserted is covered with the cover member 10 that is a separate member from the tool body 1. By covering the part of the opening of the pin hole 8 by shifting the cover member 10 as described above, the locking pin 9 can be prevented from coming off and fixed. The cover member 10 may be shifted in the circumferential direction so as to cover at least a part or all of the opening of the pin hole 8.

  In this embodiment, the cover member 10 is detachably attached by being fitted to the cover attachment portion 1D, so that the impact due to the striking force during excavation directly acts on the cover member 10. Can be avoided. Therefore, it is possible to prevent the cover member 10 from being loosened, rattled and damaged due to the wear of the cover member 10 due to such an impact, and accordingly, the locking pin 9 is prevented from falling off. Thus, the attachment member 5 can be stably attached to the attachment hole 2 to perform smooth excavation.

  Further, in the present embodiment, the outer surface of the tool body 1 in which the pin hole 8 opens is an outer peripheral surface of the cover mounting portion 1D and is formed in a cylindrical surface shape centering on the axis O parallel to the hole center line L1. On the other hand, since the cover member 10 is formed in a cylindrical shape having an inner peripheral surface opposite to the outer peripheral surface, it is easy to ensure the fitting accuracy into the cover mounting portion 1D, and more reliably hitting force. It is possible to avoid the impact caused by the above from acting on the cover member 10.

  In the present embodiment, the cover member 10 is integrally formed in a cylindrical shape from the beginning, but a divided body obtained by dividing the cylinder into a plurality of parts in the circumferential direction is joined by welding or the like, or engaged with a butting part in the circumferential direction A part may be provided and engaged to form a cylinder. In such a case, the opening of the pin hole 8 can be covered even after the attachment member 5 is attached and the locking pin 9 is inserted, and the through-hole 11 is formed in the cover member 10 or the sealing member 12 or the fixing member 14 need not be attached.

  Furthermore, in this embodiment, a through hole 11 is formed in the cover member 10 at a position where it can communicate with the opening of the pin hole 8. The sealing member that seals the through hole 11 is formed in the through hole 11. 12 is attached. For this reason, even when the cover member 10 is formed in a cylindrical shape as described above, the locking pin 9 can be easily inserted into the pin hole 8 through the through-hole 11 and the cover member 10 can be moved by shifting the cover member 10. The locking pin 9 can be prevented from coming off by covering at least a part of the through-hole 11, and even if the locking pin 9 is exposed in the remaining portion of the through-hole 11, By sealing 11, it is possible to prevent a situation in which dust that is excavation waste generated during excavation enters the through hole 11 and wears the locking pin 9.

  Therefore, the above-described configuration of the present embodiment is a device in which the tool body 1 is rotated around the axis O, in which an impact is applied to the tool body 1 during excavation, and the tool body 1 is rotated around the axis O. The mounting hole 2 is opened at a position deviated from O, the pin hole 8 is opened on the outer peripheral surface of the tool body 1, and the mounting member 5 is formed by the excavation part 6 on which the excavation tip 7 is disposed. A bit head provided at the tip of the mounting shaft portion 4, and a diameter expanding bit that rotates around the shaft center line L <b> 2 so that the radius from the axis O of the excavation portion 6 increases and decreases as the tool body 1 rotates. It is effective when applied to a drilling tool such as

  Furthermore, in the present embodiment, a cylindrical casing top Q attached to the distal end portion of the casing pipe P is disposed on the outer periphery of the cover attachment portion 1D at the distal end portion of the tool body 1, and the inner diameter of the casing top Q is arranged. However, the outer diameter of the first step portion 1B of the tool body 1 and the outer diameter of the cover member 10 are smaller than the inner diameter of the casing top Q. And the cover member 10 are disposed between the outer peripheral surface of the cover mounting portion 1D.

  For this reason, according to this embodiment, it can prevent by the cover member 10 that the flour produced at the time of excavation enters between the inner peripheral surface of the casing top Q and the outer peripheral surface of the cover mounting portion 1D. Wear of Q and cover attaching part 1D can also be prevented. In addition, the first step 1B of the tool body 1 is brought into contact with the rear end surface of the casing top Q and the rear end surface of the cover member 10 is in contact with the second step 1C during excavation. Since the through hole 11 and the pin hole 8 of the tool body 1 are disposed on the rear end side with respect to the front end surface of the casing top Q in the axis O direction, the above-mentioned dusting powder enters the through hole 11 and the pin hole 8. Abrasion of the sealing member 12 and the locking pin 9 can also be reliably prevented.

1 Tool body (device)
1A Shank part 1B 1st step part 1C 2nd step part (step part)
1D cover mounting portion 1E discharge groove 2 mounting hole portion 3 blow hole 4 mounting shaft portion 4A concave groove 5 mounting member (bit head)
6 Excavation part 7 Excavation tip 8 Pin hole 9 Locking pin 10 Cover member 11 Through hole 12 Sealing member 13 Recess 14 Fixing member O Tool body 1 axis T Tool rotation direction P Casing pipe Q Casing top L1 Hole center line (Center line of mounting hole 2)
L2 Shaft center line (center line of mounting shaft 4)
A A plane perpendicular to the shaft center line L2 C Pin hole center line

Claims (6)

An excavation tool having a tool body provided with an attachment hole, and an attachment member provided with an attachment shaft portion inserted into the attachment hole and detachably attached to the tool body,
On the outer peripheral surface of the mounting shaft portion, a concave groove is formed along a plane perpendicular to the center line of the mounting shaft portion,
The tool body is formed with a pin hole extending from the outer surface of the tool body along the plane of the mounting shaft inserted into the mounting hole and partially opening to the inner peripheral surface of the mounting hole. And
The locking pin inserted in this pin hole is locked in the concave groove of the mounting shaft portion inserted in the mounting hole portion,
An excavation tool characterized in that at least a part of the opening of the pin hole on the outer surface of the tool body can be covered with a cover member that is detachably attached to the tool body.   The outer surface of the tool main body in which the pin hole is opened is formed in a cylindrical surface centered on an axis parallel to the center line of the mounting hole, and the cover member has an inner peripheral surface facing the outer surface. The excavation tool according to claim 1, wherein the excavation tool is formed in a cylindrical shape.   The excavation tool according to claim 2, wherein the cover member is formed in a cylindrical shape in a state where a divided body obtained by dividing the cylinder into a plurality of circumferential directions is joined or engaged.   The cover member is formed with a through hole at a position where it can communicate with the opening of the pin hole, and a sealing member for sealing the through hole is attached to the through hole. The excavation tool according to any one of claims 1 to 3. The tool body is a device that rotates about an axis, and the attachment hole portion opens at a position eccentric from the axis of the tip of the tool body,
The pin hole opens in the outer peripheral surface of the outer cylindrical cover mounting portion centered on the axis formed at the tip of the tool body, and on the rear end side of the tool body from the pin hole. Is formed with a stepped part on the outer peripheral side,
The cover member is formed in a cylindrical shape, is fitted into the outer periphery of the cover mounting portion in a state where the rear end surface is in contact with the stepped portion, and covers at least a part of the opening of the pin hole,
The attachment member is a bit head in which an excavation part in which an excavation tip is disposed is provided at a tip of the attachment shaft part, and a radius of the excavation part from the axis increases or decreases as the tool body rotates. The excavation tool according to any one of claims 1 to 4, wherein the excavation tool rotates around a center line of the attachment shaft portion. A cylindrical casing top attached to the tip of the casing pipe is disposed on the outer periphery of the tip of the tool body.
The inner diameter of the casing top is smaller than the outer diameter of the stepped portion on the rear end side of the tip end of the tool body,
The excavation tool according to claim 5, wherein an outer diameter of the cover member is smaller than an inner diameter of the casing top.

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