JP6512012B2 - Drilling tool - Google Patents

Description

  The present invention is a tool body which is rotated about an axis and is given a thrust and striking force directed toward the tip end in the axial direction, and a mounting hole opened at a position eccentric to the axis of the tip of the tool body. The present invention relates to an excavating tool having a mounting shaft portion inserted into the mounting portion and a mounting member removably mounted on the tool body.

  As such an excavating tool, a mounting hole is opened at a position eccentric to the axis of the tool main body (device) tip which is rotated about the axis, and the mounting shaft is inserted into the mounting hole to be a tool A so-called enlarged diameter bit or an under reaming bit is known in which an excavated portion provided with a hard tip is provided at the tip of an attachment member (bit head) detachably mounted on the main body. There is. In such a diameter-enlarging bit, with the rotation of the tool main body, the mounting member rotates about the center line of the mounting shaft portion, and the radius from the above axis of the excavating portion is expanded and reduced. A hole can be formed, and the inside of the casing pipe inserted into the wellbore can be withdrawn and recovered in a state where the diameter is reduced.

  Thus, the excavating tool disclosed in, for example, Patent Document 1 is used to insert the mounting shaft into the mounting hole and attach the mounting member to the tool body in a removable and rotatable manner about the center line of the mounting shaft. In this case, the outer peripheral surface of the mounting shaft is formed with a recessed groove that intersects the extending direction of the mounting shaft, and the tool body extends in the direction intersecting the extending direction of the mounting hole and a part thereof is the mounting hole The pin hole which penetrates is formed, and the locking pin engaged with the concave groove of a mounting axial part is inserted in this pin hole. The recessed groove is L-shaped as viewed in the rotational axis direction of the mounting shaft portion, and the mounting member is engaged with the locking pin in the range of the L-shaped formed by the recessed groove and is rotatable and prevented from coming off It can be removed from the tool body by pulling out the locking pin from the pin hole.

  Further, in this patent document 1, as a means for fixing the locking pin to the pin hole except when removing the mounting member, the opening of the pin hole is made of a rigid body and is in contact with the end face of the locking pin. It has been proposed to provide a disc-like fixing member for fixing the locking pin and a locking portion for locking and fixing the fixing member in the extending direction of the pin hole. Furthermore, in this patent document 1, it is also proposed that a disc-like auxiliary member, which is made of an elastic body such as synthetic rubber, and maintains the locked state between the fixed member and the locking portion is also provided in the tool body. It is done.

  Here, a slide groove in which the fixing member is slide-moved is formed in the tool body so as to extend in parallel with the axis of the tool body when seen in the center line direction of the pin hole. And the locking portion is formed. The other end of the slide groove is provided with a loading portion for the fixing member, and the fixing member loaded from the loading portion is slid to one end of the slide groove and locked to the locking portion Thereafter, the auxiliary member is attached to the loading portion to press the fixing member, so that the movement of the fixing member is prevented, and the locked state between the fixing member and the locking portion is maintained.

Patent 4957440 gazette

  By the way, when forming an excavated hole by an excavating tool such as the above-mentioned enlarged diameter bit, along with the rotational force for rotating the tool body about the axis, the thrust directed to the tip side in the axial direction, and also the axial direction A striking force directed toward the tip end is applied to the tool body, and a rock or the like is broken by a mounting tip or a hard tip attached to the tip of the tool body. Then, due to the impact due to the striking force, the fixing member tends to slide and move vigorously in the slide groove extending in the axial direction of the tool body to the front end side and the rear end side.

  However, in the digging tool described in Patent Document 1, the sliding movement of the fixing member is also prevented by pressing the fixing member by the auxiliary member as described above, but the slide groove is the axis of the tool body Since the opening of the pin hole and the charging portion of the auxiliary member are also aligned in the axial direction when viewed in the center line direction of the pin hole, the pressing force when the fixing member tries to slide is It is inevitable to act on the auxiliary member. Moreover, since the fixing member is disk-shaped and the auxiliary member is also disk-shaped, the auxiliary member presses the fixing member by point contact.

  Therefore, even if the auxiliary member presses the fixing member to prevent movement, the pressing force that the auxiliary member receives when the fixing member tries to move in the slide groove is concentrated at one point facing the axial direction of the auxiliary member. As a result, the auxiliary member made of a soft elastic body may cause wear from this one point. Then, once such wear occurs and a gap is formed between the fixing member and the auxiliary member, the fixing member rapidly slides in the axial direction in the gap to accelerate the progress of the wear, and the gap rapidly If it spreads and the auxiliary | assistant member will remove | deviate from a charge part in some cases, it will become impossible to maintain the locked state of a fixing member and a latching | locking part.

  The present invention has been made under such a background, and by thus reducing the pressing force due to the fixing member trying to slide on the axial end side and the rear end side of the tool body in the axial direction. An object of the present invention is to provide a digging tool which can suppress digging of a member and maintain stable engagement between a fixed member and a locking part even in long-term digging work, thereby enabling stable digging.

  In order to solve the above problems and achieve such an object, the present invention provides a tool body which is rotated about an axis and to which an impact force is directed toward the tip end in the axial direction; A digging tool having a mounting shaft portion inserted into a mounting hole portion opened at a tip end portion and a mounting member removably mounted on the tool body, wherein an outer peripheral surface of the mounting shaft portion is A concave groove is formed along a virtual plane orthogonal to the center line of the mounting shaft, and the tool main body along the virtual plane of the mounting shaft inserted into the mounting hole in the tool body. A pin hole is formed extending from the outer peripheral surface to the inner peripheral side and partially opened to the inner peripheral surface of the mounting hole, and a locking pin is inserted into the pin hole and inserted into the mounting hole Is locked to the recessed groove of the mounting shaft portion, and the outside of the tool body is At the opening of the pin hole in the surface, a fixing member is attached which abuts on the locking pin to hold the locking pin in place, and the locking member is locked in the direction of the center line of the pin hole. A stop is formed, and a recess communicating with the opening of the pin hole is formed in the outer peripheral surface of the tool body adjacent to the opening of the pin hole, and the fixing member is formed in the recess An auxiliary member having a side surface capable of contacting the side surface facing the recess and maintaining the locking state between the fixing member and the locking portion, and viewed in the direction of the center line of the pin hole, A straight line connecting the center of the recess and the center line of the pin hole extends in a direction intersecting the axis.

  In the drilling tool configured as described above, when viewed in the center line direction of the pin hole, the center of the recess in which the auxiliary member is disposed is connected to the center line of the pin hole in which the fixing member is attached to the opening. Since the straight line extends in a direction intersecting the axis of the tool body, the axial direction of the pressing force acting when the fixing member tries to move by the striking force applied to the tool body toward the axial direction tip end side The component of force can be received by the tool body in which the opening is formed, and the pressing force that the auxiliary member receives can be reduced. Therefore, it is possible to suppress the occurrence of wear on the auxiliary member by such a pressing force, and to prevent the gap between the fixing member and the auxiliary member from expanding at once by the occurrence of the wear, and it is possible to Thus, the fixing member can be stably locked to the locking portion.

  Here, when viewed in the center line direction of the pin hole, a straight line connecting the center of the recess and the center line of the pin hole may extend in a direction diagonally intersecting the axis line, but the axis line If it extends in the direction orthogonal to the direction, substantially all of the pressing force by the striking force can be received by the tool main body, and the wear of the auxiliary member can be further reliably suppressed. Also, if the straight line connecting the center of the recess and the center line of the pin hole extends in the direction perpendicular to the axis when seen in the center line direction of the pin hole, these recesses and the pin hole are formed in the tool body The axial length of the portion can be shortened, and the manufacturing cost of the tool body can be reduced.

  Furthermore, if the recess extends from the opening of the pin hole to the side opposite to the rotation direction of the tool body, the rotation of the fixing member due to the impact when the impact force is applied while the tool body is rotated. The pressing force in the direction can also be received by the tool body, and the wear of the auxiliary member can be further suppressed.

  Therefore, in these configurations, the mounting hole is opened in the tool main body at a position eccentric to the axis of the tip, and the mounting member has the excavated portion in which the hard tip is disposed, the mounting shaft A bit head provided at the tip of the part, which rotates around the center line of the mounting shaft so that the radius from the axis of the excavating part expands as the tool body rotates The present invention is more preferable because it can be applied to a drilling tool such as a diameter bit to prevent the auxiliary member from being worn out due to an impact due to a striking force to the axial tip side.

  As described above, according to the present invention, the wear of the auxiliary member can be suppressed even in a long-term digging operation, the locked state between the fixing member and the locking portion can be maintained, and stable digging is performed. It becomes possible.

FIG. 1 is a side cross sectional view showing an embodiment of the present invention. It is the front view which looked at the state which the bit head diameter-expanded in the embodiment shown in FIG. 1 from the tip side (however, a casing pipe and a casing top are omitted in illustration). It is the front view which looked at the state which the bit head diameter-reduced in embodiment shown in FIG. 1 from the front end side (however, a casing pipe and a casing top are abbreviate | omitting illustration). It is ZZ sectional drawing in FIG. 1 (However, a casing pipe and a casing top are abbreviate | omitting illustration). FIG. 5 is a partially enlarged side view of FIG. 4 as viewed in the direction of the arrow X; It is a top view of the fixing member of embodiment shown in FIG. It is a sectional side view of the fixing member shown in FIG. It is a top view of the auxiliary member of embodiment shown in FIG. It is a sectional side view of the auxiliary member shown in FIG. It is explanatory drawing which shows the fixing method of the locking pin in embodiment shown in FIG.

  FIGS. 1 to 10 show an embodiment of the present invention, which is an application of the present invention to the above-described diameter-enlarging bit. In the present embodiment, the tool main body 1 is a device of such an enlarged diameter bit, and is formed of steel or the like into a substantially multistage cylindrical shape centering on the axis O, and its rear end (FIG. The right side portion is the shank portion 1A of the smallest diameter.

  Such a digging tool is provided with an impact force to the tip end side in the direction of the axis O by the down-the-hole hammer H connected to the shank 1A, and is connected via a digging rod not shown in the down-the-hole hammer H The rotational force about the axis O in the tool rotation direction T and the thrust toward the tip end side in the axis O direction are given from the same drilling equipment (not shown) and the ground (rock) is excavated to form an excavated hole.

  A step 1B with the largest diameter is formed on the tip side (left side in FIG. 1) of the shank 1A of the tool body 1, and the tool body 1 has a cylindrical shape with a constant outer diameter on the tip side than this step 1B. Is formed. In addition, a casing pipe P having an inner diameter slightly larger than that of the stepped portion 1B is disposed on the outer periphery of the tool main body 1, and the tip end of the casing pipe P is the tool main body 1 on the tip side of the stepped portion 1B. The casing top Q having an inner diameter slightly larger than the outer diameter of the casing is attached, and the step 1B abuts on the rear end of the casing top Q to transmit the thrust and the striking force toward the leading end in the axis O direction. The casing pipe P is inserted into the drilled hole formed by the drilling tool.

  The tip end of the tool body 1 is positioned on the tip end side of the casing top Q with the step portion 1B in contact with the rear end of the casing top Q as described above. A recess 2 is formed in the surface and the outer peripheral surface. The recess 2 has a bottom surface 2A perpendicular to the axis O facing the front end side of the tool body 1 and a flat wall surface 2B facing the tool rotation direction T extending parallel to the axis O from the bottom surface 2A to the front end surface of the tool body 1 The corner portion 2D having a flat wall surface 2C facing the outer peripheral side of the main body 1 and the wall surfaces 2B and 2C intersect is formed in a concave cylindrical surface shape having a center line parallel to the axis O. In the present embodiment, three such concave portions 2 are formed at equal intervals in the circumferential direction.

  Further, from the bottom surface 2A of the concave portion 2 toward the rear end side, the mounting hole portion 3 in the present embodiment is formed. The mounting hole 3 is formed in a circular cross-section with a constant inner diameter centered on a hole center line L1 parallel to the axis O and eccentric to the outer peripheral side from the axis O. This hole center line L1 The corner portion 2D is disposed coaxially with the center line of the concave cylindrical surface formed by the corner portion 2D, and the inner diameter (diameter) of the mounting hole 3 is slightly smaller than the diameter of the concave cylindrical surface formed by the corner portion 2D.

  The mounting member 5 in which the mounting shaft 4 is inserted into the mounting hole 3 and detachably mounted on the tool body 1 is a bit head of the expanded bit in this embodiment. The drilling portion 6 is integrally formed at the tip end. A hard tip 7 made of cemented carbide or the like having a hardness higher than that of the tool body 1 made of steel or the like and the mounting member 5 is embedded in the end surface of the excavating portion 6 and the recessed portion 2 of the tool body 1. The ground is broken by these hard tips 7 and excavation is performed.

  The mounting shaft 4 is in the form of a cylindrical shaft centered on the shaft center line L2, and is formed so that the outer diameter thereof is slightly smaller than the inner diameter of the mounting hole 3, and its length is mounting It is formed to be substantially equal to the depth of the hole 3. Accordingly, the mounting shaft portion 4 is slidably fitted in the mounting hole portion 3, the shaft portion center line L 2 is inserted coaxially with the hole center line L 1, and the end face abuts on the bottom surface of the mounting hole portion 3. By the way, the rear end face of the excavating part 6 comes in contact with the bottom face 2A of the recess 2, and the mounting member 5 is rotatable around the hole center line L1 in the inserted state where the mounting shaft 4 is inserted into the mounting hole 3 It is assumed.

  In addition, the excavating portions 6 are substantially parallel as shown in FIGS. 2 and 3 in a front end view, or are closer to each other at an angle smaller than the angle formed by the wall surfaces 2B and 2C of the recess 2 It has two flat side surfaces and two convex cylindrical surface side surfaces extending between the side surfaces of the mounting shaft 4 and the opposite side of the mounting shaft 4, and these side surfaces are the shaft center line L2 Parallel to the hole center line L1 and the axis O of the tool body 1 in the inserted state. Among them, the side surface of the convex cylindrical surface on the mounting shaft 4 side is a cylindrical surface centered on the shaft center line L2, and the radius thereof is slightly smaller than the radius of the concave cylindrical surface formed by the corner portion 2D of the recess 2 It is small, and can be in sliding contact with the corner 2D in the inserted state.

  Therefore, when the tool body 1 is rotated in the tool rotation direction T at the time of excavation in this inserted state, the attachment member 5 is rotated about the hole center line L1 in the opposite direction of the tool rotation direction T by the resistance from the ground. The radius of the diameter of the cutting edge 6 expanded, and the flat side face of the excavating portion 6 directed to the opposite side of the tool rotation direction T abuts the wall surface 2B of the recess 2 facing the tool rotation direction T as shown in FIG. By the way, it is positioned. At this time, the side surface of the convex cylindrical surface opposite to the mounting shaft 4 of the excavating portion 6 is located on a cylindrical surface having an outer diameter larger than that of the casing pipe P centered on the axis O of the tool main body 1, The hard tip 7 disposed on the front end side forms a drill hole into which the casing pipe P can be inserted.

  In addition, when the tool body 1 is rotated to the opposite side of the tool rotation direction T at the time of excavation after the completion of excavation, the mounting member 5 is also rotated around the hole center line L1 in the tool rotation direction T due to the resistance from the ground. The radius from the axis O is reduced, and the flat side surface of the excavating part 6 directed to the inner peripheral side of the tool main body 1 abuts on the wall surface 2C facing the outer peripheral side of the tool main body 1 of the recess 2 as shown in FIG. It will be positioned where you At this time, the excavating portion 6 is housed in a cylindrical surface having an outer diameter equal to the outer diameter of the column formed by the tip end portion of the tool body 1 with respect to the step portion 1B, and the mounting member 5 together with the down the hole hammer H and the digging rod Thus, the tool body 1 can be retracted to the rear end side in the direction of the axis O and pulled out of the casing pipe P.

  Furthermore, on the outer peripheral surface of the mounting shaft portion 4 of such a mounting member 5, along a virtual plane orthogonal to the shaft center line L2, ie, a virtual plane A orthogonal to the hole center line L1 in the inserted state. The recessed groove 4A is formed. The recessed groove 4A is formed on the side surface side of the convex cylindrical surface of the drilling portion 6 on the attachment shaft 4 side as viewed from the direction of the shaft center line L2, and the cross section along the virtual plane A is L in this embodiment. It is formed in the shape of a letter, but the bent part of this L character is formed in the shape of a convex arc centered on the axial center line L2 in contact with the linearly extending parts on the both sides. Further, as shown in FIG. 1, the concave groove 4A is formed in a half oval shape extending in the direction of the axial centerline L2 in a cross section along the axial centerline L2.

  On the other hand, pin holes 8 are formed in the tool main body 1 along an imaginary plane A which is also orthogonal to the hole center line L1 in the inserted state. The pin holes 8 are circular in cross section in this embodiment, and are substantially in contact with the inner peripheral surfaces of the three attachment holes 3 formed at equal intervals in the circumferential direction from the side opposite to the tool rotational direction T. Each has an extending pin hole center line C, and is formed in a blind hole shape which is open on the outer peripheral surface of the tool main body 1 and goes to the inner peripheral side. Therefore, these pin holes 8 are partially opened in the inner peripheral surface of the mounting hole 3 at a portion where the pin hole center line C substantially contacts the inner peripheral surface of the mounting hole 3.

  Further, the radius of the pin hole 8 is substantially equal to the depth from the outer peripheral surface of the mounting shaft 4 to the groove bottom of the recessed groove 4A at a portion in contact with the inner peripheral surfaces of the two mounting holes 3. The opening of the pin hole 8 to the outer peripheral surface of the tool main body 1 is open to the outer peripheral surface of the tool main body 1 with the same radius except for a locking portion described later. Then, 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, and one end face of the tool body 1 facing the inner peripheral side is the pin It is made to abut on the bottom of the hole 8 and is engaged with the concave groove 4 A of the mounting shaft 4 of the mounting member 5 inserted into the mounting hole 3.

  Further, a fixing member 10 is attached to the opening of the pin hole 8 so as to abut on the other end face of the locking pin 9 and lock the locking pin 9 in the direction of the pin hole center line C between the opening and this opening. At the same time, a locking portion 11 for locking the fixing member 10 itself in the direction of the pin hole center line C is formed. Furthermore, a recess 12 communicating with the opening of the pin hole 8 is formed on the outer peripheral surface of the tool body 1 adjacent to the opening of the pin hole 8, and the recess 12 is provided with a fixing member An auxiliary member 13 is disposed to maintain the locked state of 10 and the locking portion 11.

  Here, the recess 12 is formed to communicate with the opening of the pin hole 8 as shown in FIGS. 4 and 5, and the extension 12A extends with a width equal to the diameter of the circle formed by the opening. And a circular portion 12B having a diameter larger than that of the pin hole 8 having a center line parallel to the pin hole center line C on the opposite side to the pin hole 8 of the extension 12A. The distance between the center D of the circular portion 12B and the pin hole center line C is set slightly larger than the sum of the radius of the circular portion 12B and the radius of the pin hole 8.

  Further, a groove is formed at an inner peripheral portion of the pin hole 8 and the recess 12 with a slight gap between the outer peripheral surface of the tool main body 1 and the inner peripheral portion of the pin hole 8 among them. The formed groove is used as the locking portion 11 in the present embodiment. Further, in the present embodiment, the groove formed on the inner periphery of the circular portion 12B in the recess 12 is referred to as the recess side locking portion 12C, and the groove formed in the extension portion 12A is a slide in the present embodiment The groove 12D is used.

  The locking portion 11, the recess side locking portion 12C, and the slide groove 12D are formed along one virtual plane orthogonal to the pin hole center line C, that is, they face the pin hole center line C direction. The two groove wall surfaces facing each other are formed flush with each other by the locking portion 11, the recess-side locking portion 12C, and the slide groove 12D. Further, these two groove wall surfaces are formed perpendicularly to the pin hole center line C, and the pin holes 8 between these groove wall surfaces and the groove bottom facing the inside of the recess 12 are perpendicular to the groove wall surfaces, that is, pin holes The locking portion 11, the recess-side locking portion 12C, and the slide groove 12D are formed in parallel to the center line C, and the cross section along the pin hole center line C is formed in a rectangular shape.

  The groove depth of the groove formed by the locking portion 11, the recess side locking portion 12C, and the slide groove 12D, that is, the inner circumferences of the pin hole 8 and the extending portion 12A of the recess 12 and the circular portion 12B. While the depth to the groove bottom is formed to be equal and constant with the locking portion 11 and the slide groove 12D, in the recess side locking portion 12C, these locking portions 11 and It is formed to have a constant groove depth shallower than the groove depth of the slide groove 12D.

  Among them, the fixing member 10 to be locked to the locking portion 11 is formed in a disk shape as shown in FIGS. 6 and 7 by a rigid body such as a steel material as the tool main body 1 etc. A flange portion 10A is formed on the side of the bottom surface (the lower surface in FIG. 7) of the side surface. The flange portion 10A has a thickness from the bottom surface of the fixing member 10 slightly smaller than the groove width between the two groove wall surfaces of the groove formed by the locking portion 11 and the slide groove 12D. It is formed in the cross section rectangular shape of fixed amount of protrusion equal to the said groove depth of stop part 11 and slide groove 12D, and is formed in the perimeter of the disk which fixing member 10 makes. Further, the fixing member 10 is formed such that the radius thereof is slightly smaller than the radius of the pin hole 8 on the upper surface (upper surface in FIG. 7) side of the flange portion 10A.

  Therefore, the fixing member 10 thus formed can be inserted into the recess 12 with its bottom surface directed to the inner peripheral side of the tool main body 1 as will be described later with reference to FIG. When 10A coincides with the locking portion 11 and the slide groove 12D in the direction of the pin hole center line C, the flange portion 10A is slid along the slide groove 12D toward the opening of the pin hole 8 to obtain the locking portion 11 and The slide groove 12D can be locked in the direction of the pin hole center line C and attached to the opening of the pin hole 8.

  On the other hand, the auxiliary member 13 disposed in the recess 12 is also formed in a disc shape as shown in FIGS. 8 and 9 by an elastic body such as a synthetic rubber such as urethane rubber also in this embodiment. There is. A flange portion 13A slightly larger in diameter than the upper surface (upper surface in FIG. 9) is also formed on the bottom surface (lower surface in FIG. 9) side of the auxiliary member 13 and the diameter of the flange 13A Is formed on the upper surface side to be approximately equal to the inner diameter of the recess-side locking portion 12C and gradually smaller toward the bottom surface side, and the diameter of the side surface of the auxiliary member 13 on the upper surface side than the flange portion 13A is concave The inner diameter of the circular portion 12B of the portion 12 is substantially equal.

  The straight line E connecting the center D of the recess 12 to which the auxiliary member 13 is attached and the pin hole center line C is seen in the direction of the pin hole center line C as shown in FIG. Extends in the direction intersecting with the axis, that is, the extension 12A of the recess 12 extends from the opening of the pin hole 8 in the direction intersecting the axis O to reach the circular portion 12B, and in the present embodiment the axis O It extends in the direction perpendicular to the Further, the recess 12 extends in the circumferential direction of the tool body 1 from the opening of the pin hole 8 in the opposite direction to the tool rotational direction T.

  Here, the distance between the pin hole center line C and the center D of the recess 12 in the straight line E direction is the sum of the radius of the flange portion 10A of the fixing member 10 and the radius of the upper surface side of the flange portion 13A of the auxiliary member 13 Therefore, the auxiliary member 13 can contact the side surface of the flange portion 10A where the flange portion 13A faces the recess 12 of the fixing member 10, and the engagement between the fixing member 10 and the locking portion 11 Maintain the stop state.

  Three discharge grooves 14 for discharging excavated chips generated at the time of excavating are formed on the bottom surface 2A of the three concave portions 2 of the mounting hole portion 3 on the outer peripheral portion on the tip side from the step portion 1B of the tool body 1. It is formed to open in the tool rotation direction T side, and the bottom surface 2A at the opening has a step so as to slightly recede to the rear end side in the axis O direction on the outer peripheral side as shown in FIG. . Furthermore, in the tool body 1, a supply hole 15 for supplying a fluid such as compressed air sent from the drilling machine side extends along the axis O as shown in FIG. 1, and this supply hole 15 is a tool body A branch is made at the tip end of the opening 1 and is open to the recessed portion of the bottom surface 2A of the recess 2, the wall surface 2C, and the outer peripheral surface of the tool main body 1.

  In such a digging tool, the mounting shaft portion 4 of the mounting member 5 which is a bit head is inserted into the mounting hole portion 3 of the tool main body 1 which is a device, and the digging portion 6 is accommodated in the recess 2 as shown in FIG. By inserting the locking pin 9 into the pin hole 8 and locking it in the concave groove 4A of the mounting shaft 4 as shown in FIG. Furthermore, as shown in FIG. 10 (b), after the fixing member 10 inserted in the recess 12 is slid and locked to the locking portion 11 of the opening of the pin hole 8, as shown in FIG. 10 (c) By pressing the auxiliary member 13 which is an elastic body into the recess 12 while elastically deforming it, the flange portion 13A spreads where it enters the recess-side locking portion 12C and closely contacts the flange portion 10A of the fixing member 10, The fixing member 10 is prevented from coming off.

  The drilling tool configured in this way is inserted into the casing pipe P in a state in which the diameter of the drilling portion 6 of the mounting member 5 is reduced, and the step 1B of the tool body 1 is in contact with the casing top Q as described above The excavating portion 6 is expanded by applying a rotational force about the axis O, and a thrust and striking force to the tip end side in the axis O direction is further applied to form an excavated hole, and a casing pipe is formed in the excavated hole I will insert P. In addition, when the drilling hole is formed to a predetermined depth and the casing pipe P is inserted, the diameter of the digging portion is reduced by rotating the tool main body 1 to the opposite side of the tool rotation direction T as described above. It can be withdrawn from P and recovered.

  And, in the drilling tool having the above configuration, a straight line E connecting the center D of the recess 12 in which the auxiliary member 13 is disposed and the pin hole center line C, viewed in the direction of the pin hole center line C, Among the pressing forces acting when the fixing member 10 extending in the direction intersecting the axis O and attached to the opening of the pin hole 8 tries to move by the striking force toward the tip end in the direction of the axis O, The component force in the direction of the axis O can be received by the tool body 1 itself in which the opening of the pin hole 8 is formed.

  Therefore, the pressing force received by the auxiliary member 13 can be reduced, and the wear of the soft auxiliary member 13 made of an elastic body can be suppressed, and once the wear occurs, the fixing member 10 and the auxiliary member 13 The gap between the two members is prevented from expanding at a stretch, and the locking state of the fixing member 10 to the locking portion 11 is reliably maintained, and the auxiliary member 13 comes off and the fixing member 10 and the locking pin 9 accompanying this. Can be prevented from falling out. Therefore, the fixing member 10 can be stably locked to the locking portion 11 of the opening of the pin hole 8 over a long period of time, and smooth excavation can be performed.

  In particular, in the present embodiment, a straight line E connecting the center D of the recess 12 and the pin hole center line C extends in a direction orthogonal to the axis O of the tool body 1 when viewed in the pin hole center line C direction. Therefore, the tool body 1 can receive substantially all of the pressing force by the striking force applied to the tool body 1, and the wear of the auxiliary member 13 can be more reliably suppressed. In addition, since the straight line E is orthogonal to the axis O in this way, the space in the direction of the axis O necessary for the tool body 1 to form the recess 12 is only the size of the recess 12 itself. The length of the tool body 1 in the direction of the axis O can also be reduced, and the manufacturing cost of the tool body 1 can be reduced.

  In this embodiment, the straight line E extends in the direction perpendicular to the axis O as seen in the direction of the pin hole center line C in this manner, but the straight line L extends in the direction obliquely intersecting the axis O It is also good. However, when the straight line E extends obliquely in the direction intersecting the axis O as seen in the direction of the pin hole center line C, if the inclination angle of the straight line E with respect to the direction orthogonal to the axis O is too large The component force in the direction of the axis O of the pressing force of the fixing member 10 can not be sufficiently received by the tool main body 1 and there is a possibility that the wear of the auxiliary member 13 can not be suppressed. Even when the recess 12 extends from the opening of the pin hole 8 to the opposite side to the tool rotation direction T as in the above embodiment, or in the tool rotation direction T as in the embodiment, It is desirable that the range from the opening of the pin hole 8 toward the front end side or the rear end side in the direction of the axis O be 60 ° or less, that is, the inclination angle of the straight E to the axis O be in the range of 30 ° to 150 °. Desirable to be .

  Further, in the present embodiment, the recess 12 extends from the opening of the pin hole 8 in the opposite direction to the tool rotation direction T. For this reason, the pin formed in the tool main body 1 is also a pressing force of the fixing member 10 in the tool rotational direction T due to an impact when the tool main body 1 is rotated about the axis O and receives an impact force on the tip side in the axis O direction. Since it can be received by the opening of the hole 8, it is possible to suppress the occurrence of wear on the auxiliary member 13 due to such pressing force in the tool rotational direction T.

  Therefore, the above-described configuration of the present embodiment is a device in which the tool body 1 is rotated about the axis O when a striking force is given to the tool body 1 at the time of excavation as described above, and the axis of the tip portion The mounting hole 3 is opened at a position eccentric to O, the pin hole 8 is opened in the outer peripheral surface of the tool body 1, and the mounting member 5 is an excavated portion 6 in which the hard tip 7 is disposed. A bit head provided at the tip of the mounting shaft 4 that rotates around the shaft center line L2 so that the radius from the axis O of the excavating part 6 expands as the tool body 1 rotates. It is effective to apply to such drilling tools.

DESCRIPTION OF SYMBOLS 1 tool main body 2 recessed part 3 mounting hole 4 mounting shaft part 4A recessed groove 5 mounting member 6 digging part 7 hard tip 8 pin hole 9 locking pin 10 fixing member 10A flange part of fixing member 10 locking portion 12 recess 12C Recess side locking part 13 Auxiliary member 13A Flange part of auxiliary member 13 Axis line of tool main body 1 Tool rotation direction A Virtual plane C where concave groove 4A and pin hole 8 are formed C Pin hole center line (pin hole 8 Center line)
D Center of recess 12 (center of circular part 12B)
E Straight line connecting the center D of the recess 12 to the pin hole center line C when viewed from the pin hole center line C direction L1 hole center line (center line of the mounting hole 3)
L2 shaft center line (center line of mounting shaft 4)

Claims (4)

A tool body which is rotated about an axis and to which an impact force directed to the tip end side in the axial direction is given, and a mounting shaft portion inserted into a mounting hole portion opened at the tip portion of the tool body A drilling tool having a mounting member removably mounted on the
A recessed groove is formed on an outer peripheral surface of the mounting shaft portion along a virtual plane orthogonal to the center line of the mounting shaft portion,
The tool body extends from the outer peripheral surface of the tool body to the inner peripheral side along the imaginary plane of the mounting shaft portion inserted into the mounting hole portion and partially on the inner peripheral surface of the mounting hole portion An open pin hole is formed,
A locking pin is inserted into the pin hole and is locked to the recessed groove of the mounting shaft portion inserted into the mounting hole portion,
At the opening of the pin hole in the outer peripheral surface of the tool body, a fixing member is mounted which abuts on the locking pin and prevents the locking pin from coming off, and the fixing member is mounted in the center line direction of the pin hole. A locking portion for locking to the
A recess communicating with the opening of the pin hole is formed on the outer peripheral surface of the tool body adjacent to the opening of the pin hole,
An auxiliary member is disposed in the recess, the side member having a side surface capable of coming into contact with the side surface of the fixing member facing the recess so as to maintain the locked state between the fixing member and the locking portion.
A cutting tool characterized in that a straight line connecting a center of the recess and a center line of the pin hole extends in a direction intersecting with the axis when viewed in the center line direction of the pin hole.   The straight line connecting the center of the recess and the center line of the pin hole extends in a direction perpendicular to the axis when viewed in the center line direction of the pin hole. Drilling tools.   The drilling tool according to claim 1 or 2, wherein the recess extends from the opening of the pin hole in the opposite direction to the rotational direction of the tool body. In the tool main body, the mounting hole opens at a position eccentric to the axis of the tip end portion,
The mounting member is a bit head in which a digging portion in which a hard tip is disposed is provided at the tip of the mounting shaft portion, and the radius from the axis of the digging portion is expanded or reduced as the tool body rotates. The drilling tool according to any one of claims 1 to 3, wherein the drilling tool rotates around the center line of the mounting shaft portion.

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