JPH1136770A - Boring bit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the main bit of a boring bit with a subsidiary bit in a manner that allows it to be rotated by a set angle for adjustment, make the circular portion of the subsidiary bit project outside the external circumference of the main bit and perform boring together with the main bit during boring, and make the truncated circular portion stored in the external circumference line of the main bit by rotating the subsidiary bit by a set angle for adjustment during boring bit recovery. SOLUTION: The boring bit A is furnished with at least one subsidiary bit 6 with an equal circular arc angle point on a concentric circle line around the center of the main bit smaller than the inside diameter of an embedded pipe 2 as the center of a spindle 5, the subsidiary bit 6 is provided in a manner that allows it to be rotated by a set angle normally or reversely for adjustment by the normal or reverse rotation of a main shaft 1. The subsidiary bit 6 is comprised of a truncated circular portion 6b and a circular portion 6a, and during boring by the normal rotation of the main shaft 1, a part of the circular portion of the subsidiary bit 6 is projected outside the circumference line of the main bit 3, and during the recovery of the boring bit A, the truncated circular portion 6b is positioned inside the external circumference line of the main bit 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting bit which is attached to the tip of a main shaft and drills and drills various types of ground, and more particularly to a method of burying a buried pipe (such as a steel pipe) in parallel with the drilling. In addition, a small circular sub-bit is provided in a part of the main bit of the cutting bit so as to be able to adjust the rotation of the set angle, so that the circular portion of the sub-bit projects outside the outer circumferential line of the main bit during cutting. When cutting and collecting through the buried pipe for exchanging the cutting bit, etc., rotate the sub-bit by the set angle and put the missing part inside the outer circumference of the main bit, Provided is a cutting bit for boring or the like, in which the cutting bit can be easily pulled out and collected.

[0002]

2. Description of the Related Art A cutting bit (a large number of bits are protruded on the front surface) is attached to the tip of a rotationally driven main shaft to perform boring cutting of various types of ground such as rock, gravel, and stone layers. When cutting and burying pipes, and especially when cutting long distances, the cutting bits will be worn and damaged,
Alternatively, it is necessary to repair and replace the cutting bit during cutting in order to cope with various types of hard and soft ground.

[0003] In this case, the main axis is set to the outside (starting point / ground surface,
It is necessary to remove the cutting bit at the tip and replace it.However, it is not easy to pull out through the drilling hole even with ordinary boring drilling due to friction with the inner wall of the hole. In the case of the method of burying buried pipes in parallel with the progress of cutting by burial cutting of pipes, the inner diameter of the buried pipe is naturally smaller than the outer diameter of the cutting bit at the tip. For this reason, it is impossible to pull out the cutting bit through the buried pipe.

Therefore, in order to remove the cutting bit through the buried pipe in order to replace the cutting bit, it is necessary to reduce the outer diameter of the cutting bit from the time of cutting.

In order to solve the above-mentioned problem, conventionally, for example, although not shown in the drawings, the cutting bits are divided and configured.
When the main shaft is pressurized and rotated forward (cutting), a wedge-like object moves forward to expand the divided bit to the periphery and cut it. Something like retreats and the cutting bit shrinks, so
It can be pulled out and replaced through the buried pipe,
In addition, various attempts have been made, but in any case, the operation of expanding and contracting the cutting bit does not work smoothly. The current situation is that troubles occur frequently and effective means are not provided yet.

[0006]

In view of the above, the enlarging / reducing operation of the cutting bit can be variously designed in view of the design.
It is an object of the present invention to provide a tightly closed structure with no gap for earth and sand to enter.

The present invention solves the above-mentioned problem effectively by providing a sub-bit consisting of a circular portion and a non-circular portion in a main bit of a cutting bit so as to be freely rotatable at a set angle. It is assumed that.

[0008]

That is, the present invention relates to a circular cutting method for drilling and drilling the ground such as drilling and drilling various pipes, which is detachably attached to the tip of a rotating spindle. In hex bits,

The cutting bit has at least one sub-bit centered on an equiangular angle point on a concentric line centered on the center of a circular main bit having a diameter smaller than the inner diameter of the buried pipe, and has at least one sub-bit. The bit is provided so that the set angle rotation can be freely adjusted by switching the main shaft between forward and reverse rotations, and the sub-bit is made up of a truncated circular portion and a circular portion in which a small circular part is cut out,

[0010] At the time of cutting by the forward rotation of the main shaft, a part of the circular portion of the sub-bit is projected outside the outer peripheral edge of the main bit, and the cut-out portion is positioned toward the center of the main bit. In this state, the main and sub-bits are prepared so that they can be rotated and rotated in the same direction as the main shaft.

When the cutting bit is pulled out and collected, the sub-bit is rotated at the set angle by the reverse rotation of the main shaft at the set angle, and the cutout portion is provided so as to be positioned inside the outer circumferential line of the main bit. The problem is solved by a cutting bit for boring and the like.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. Removably attached to the tip of the rotating spindle 1
In the circular drill bit A for drilling and drilling the ground such as drilling and drilling various pipes,

At least one cutting bit A is set at an equiangular angle point on a concentric line 4 centered on the center of a circular main bit 3 having a diameter smaller than the inner diameter of the buried pipe 2 (steel pipe). And the sub-bit 6 is provided so as to be capable of adjusting the forward / reverse rotation of a set angle (eg, 180 °) by switching the main shaft 1 between forward and reverse rotations. It consists of a cutout part 6b and a circle part 6a in the shape of a notch,

When the main shaft 1 is ground by forward rotation, a part of the circular portion 6a of the sub-bit 6 projects outside the outer circumferential line 7 of the main bit 3 and the missing circular portion 6b is positioned at the main bit 3. , And in this state, the main and sub-bits 3 and 6 are prepared so as to be cut in rotation with the forward rotation of the main shaft 1,

When the cutting bit A is pulled out and collected, the sub-bit 6 is rotated by the reverse rotation of the main shaft 1 at the set angle (eg, 180 °).
Is rotated by a set angle (e.g., 180 °) so that the cutout portion 6b is positioned inside the outer circumferential line 7 of the main bit 3 and a cutting bit A for boring or the like is provided. is there.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above-described cutting bit A, the sub-bit 6 is set at a set angle (for example, 18) by the forward and reverse rotation of the main shaft 1.
0 °) As means to rotate forward and backward,

A gear 8 is formed on the circumference of the tip of the main shaft 1,
A gear 9 is provided on the inner periphery of the support shaft 5 of the sub-bit 6 facing the gear 8.
Is formed so as to mesh with both gears 8 and 9, and the gear between the set arc angles of the gear 9 is cut out to form a toothless portion 9 a
So that the gears 8 and 9 are disengaged from each other between the set arc angles (FIGS. 2 and 3).

At the time of cutting to rotate the main shaft 1 forward, the gear 8 of the main shaft 1 is disengaged from the toothless portion 9a of the gear 9 of the sub-bit 6 so that the gears 8 and 9 are disengaged from each other, and the circle of the sub-bit 6 is rotated. The portion 6a is positioned so as to protrude outside the outer circumferential line 7 of the main bit 3, so that the main and sub bits 3, 6 rotate in the forward rotation direction with the main shaft 1 to perform cutting (FIG. 1). , FIG. 2, FIG. 4, FIG. 5)

The reverse rotation of the main shaft 1 at the set angle (eg, 180 °) causes the two gears 8 and 9 to mesh with each other, causing the sub-bit 6 to rotate at the set angle (eg, 180 °).
Is located inside the outer circumferential line 7 of the main bit 3,
The cutting bit A is provided so that it can be pulled out and collected through the buried pipe 2. (Fig. 3)

The means for rotating the sub-bit forward / reverse by the forward / reverse rotation of the main shaft is not limited to the above-described gear configuration, and a stopper, a cam, etc. are relatively installed on the main shaft and the sub-bit support shaft. In short, when the cutting bit is cut by forward rotation of the main shaft, the inside of the sub-bit protrudes outside the outer circumferential line of the main bit, and the rotation of the sub-bit about the spindle stops. The main and sub-bits are provided so that they can be rotated in the same direction as the main shaft to perform cutting. Also, when the main shaft is rotated in the reverse direction by the set angle, the support shaft of the sub-bit rotates by the set angle for the first time, and May be any configuration as long as it is located inside the outer circumferential line of the main bit so as to extract and collect the cutting bit through the buried pipe.

As examples of cutting bits for performing normal straight cutting, as shown in FIGS. 1, 2 and 3, the cutting surfaces of the main and sub bits 3 and 6 of the cutting bit A are It is formed at right angles to the center axis 10,

In the case of the cutting bit A in which the cutting direction can be freely controlled by measuring the target provided near the cutting bit A in the course of the straight cutting with the transit on the starting pit side, the cutting of the main bit 3 is performed. The advance surface is formed so as to be inclined at a set angle (for example, about 10 °) with respect to the center axis 11 of the main shaft 1, and the advancing surface when the sub-bit 6 installed on the main bit 3 is abraded is used as the main bit 3.
It is formed with the same inclination. (FIGS. 4 and 5)

When the cutting bit A on the inclined cutting surface is moved forward by the impact of the air hammer 11 or the like while the rotation of the main spindle 1 is stopped, the cutting bit A is inclined without moving straight. The direction of the point 12 of the surface (the point 12 of FIG. 4)
From the point 12 to the lower left and from the point 12 in FIG. 5 to the lower right), the cutting direction can be freely adjusted by advancing the point toward the correction target direction. Can be controlled.

[0024]

When the main shaft 1 is rotated forward, that is, the cutting bit A is rotated forward and cut, and at the same time, the buried pipe 2 is pulled by the cutting bit and buried as shown in FIG. Spindle 1
The rotation of the sub-bit 6 (due to the rotation of the support shaft 5) is stopped in a state where the gear 8 of the sub-bit 6 and the gear 9 of the support shaft 5 of the sub-bit 6 are disengaged at the toothless portion 10, and at the same time, the sub-bit 6 Circle part 6a
Are protruded outside the outer circumferential line 7 of the main bit 3, and therefore, when the cutting bit A is driven in the forward rotation, a hole having the same diameter or a large diameter as the buried pipe 2 is cut, and The buried pipe 2 is buried along with the cutting of the cutting bit A.

Next, in order to cope with wear and breakage of the cutting bit A and changes in the hardness of the ground, etc., the cutting bit A
When it becomes necessary to pull out and collect to the starting pit side, and to exchange, repair, etc., the main shaft 1 is set at the set angle (180 ° in the illustrated example).
When the gear rotates in the reverse direction, for example, the gears 8 and 9 which have been disengaged as shown in the figure mesh with each other, and the sub-bit 6 is rotated by a set angle (180 ° in the illustrated example) by the rotation of the support shaft 5, and the missing circular portion 6 b Is located inside the outer circumferential line 7 of the main bit 3, so that the cutting bit A whose diameter is smaller than the inner diameter of the buried pipe 2 is pulled out and collected through the buried pipe 2.

When the exchange or repair of the collected cutting bit A is completed, the cutting bit A is returned to the excavation position through the buried pipe 2 and the main shaft 1 is rotated forward again. By the gears 8 and 9 meshed by the rotation operation, the support shaft 5 and the sub-bit 6 are set at a set angle (180 in the illustrated example).
°) Restoring rotation, reaches the toothless portion 9a, the gears 8 and 9 are disengaged and the sub-bit 6 stops, and at the same time, the circular portion 6a of the sub-bit 6 The main and sub-bits 3 and 6 are rotated by the forward rotation of the main shaft 1 because they are positioned to protrude outward.
That is, the cutting bit A is rotated forward to perform cutting again.

Normally, the cutting operation is performed while measuring the cutting direction of a target provided near the cutting bit with a transit provided on the starting pit side or the like. There are many cases where the wheel is cut away from the target direction due to the above. At that time, as shown in FIGS.
In the case of the cutting bit A in which the cutting surfaces of the main and sub bits 3 and 6 are formed to be inclined, once the forward rotation of the main shaft 1 is once stopped,
The cutting bit A is blown by the air hammer 11 or the like while the tip 12 of the inclined cutting surface of the cutting bit A is directed to the correction target direction (for example, FIG. 4 is inclined downward, and FIG. 5 is inclined right downward). When the cutting bit A advances, the cutting bit A moves forward toward the tip 12 by the resistance guide of the inclined cutting surface, and corrects the cutting direction. Is what you do.

[0028]

[Effect] When the main shaft is rotated forward, the circular portion of the sub-bit stops at a position where it protrudes outside the outer circumferential line of the main bit. When the main shaft is rotated at the set angle in the reverse direction, the sub-bit automatically rotates at the set angle, and the missing part is located inside the outer circumferential line of the main bit. There is an excellent effect that the cutting bit having a small diameter can be pulled out and collected through the buried pipe, and can be replaced or repaired.

Since a small circular sub-bit is provided so as to be capable of normal and reverse rotation adjustment at each equi-arc angle point on a concentric line centered on the center of the circular main bit, the main bit and the sub-bit can be freely adjusted. It is only necessary to perform the fitting processing of the bit in the tangential state of the circles, so that the processing can be performed precisely and easily, and the auxiliary bit only rotates the set angle within the tangent of the circles. No gap is generated during the rotation operation, and therefore there is no possibility that excavated earth and sand or the like may enter the gap and cause malfunction.

Further, by forming the fronts of the main and sub bits of the cutting bit on the inclined cutting surface, the cutting bit can be corrected and cut in the direction of the tip of the inclined cutting surface. There is an excellent feature that the cutting direction can be freely controlled just by adjusting the position of the part.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of an embodiment of a cutting bit according to the present invention, in which a circular portion of a sub-bit projects outside an outer circumferential line of a main bit and is cut by a forward rotation of a main shaft. FIG.

FIG. 2 is a front view of FIG. 1;

FIG. 3 is a front view of FIG. 1 and shows a setting angle (180 °) of a main shaft.
FIG. 8 is a diagram showing a state in which the missing portion of the sub-bit is positioned inside the outer circumferential line of the main bit by the reverse rotation, and the cutting bit can be pulled out and collected through the buried pipe.

FIG. 4 is a vertical sectional front view of an embodiment in which the fronts of the cutting bits (main and sub bits) are formed to be inclined.

FIG. 5 is an explanatory view showing a state in which a buried pipe (steel pipe) is buried in parallel with the cutting by the cutting bit (FIG. 4) of the present invention.

[Explanation of symbols]

 A Cutting bit of the present invention 1 Main shaft 2 Buried pipe (eg steel pipe) 3 Main bit 4 Concentric line 5 Support shaft 6 Sub-bit 6a Circular portion 6b Missing circular portion 7 Outer circumferential line of main bit 8 Gear (main shaft) 9 Gear (Support shaft) 9a Tooth missing part 10 Center axis of main shaft 11 Air hammer 12 Sharp end 13 Ground

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[Procedure amendment]

[Submission date] September 9, 1997

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Cutting bits for boring etc.

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting bit which is attached to the tip of a main shaft and drills and drills various types of ground, and more particularly to a method of burying a buried pipe (such as a steel pipe) in parallel with the drilling. In addition, a small circular sub-bit is provided in a part of the main bit of the cutting bit so as to be able to adjust the rotation of the set angle, so that the circular portion of the sub-bit projects outside the outer circumferential line of the main bit during cutting. When cutting and collecting through the buried pipe for exchanging the cutting bit, etc., rotate the sub-bit by the set angle and put the missing part inside the outer circumference of the main bit, Provided is a cutting bit for boring or the like, in which the cutting bit can be easily pulled out and collected.

[0002]

2. Description of the Related Art A cutting bit (a large number of bits are protruded on the front surface) is attached to the tip of a rotationally driven main shaft to perform boring cutting of various types of ground such as rock, gravel, and stone layers. When cutting and burying pipes, and especially when cutting long distances, the cutting bits will be worn and damaged,
Alternatively, it is necessary to repair and replace the cutting bit during cutting in order to cope with various types of hard and soft ground.

[0003] In this case, the main axis is set to the outside (starting point / ground surface,
It is necessary to remove the cutting bit at the tip and replace it.However, it is not easy to pull out through the drilling hole even with ordinary boring drilling due to friction with the inner wall of the hole. In the case of the method of burying buried pipes in parallel with the progress of cutting by burial cutting of pipes, the inner diameter of the buried pipe is naturally smaller than the outer diameter of the cutting bit at the tip. For this reason, it is impossible to pull out the cutting bit through the buried pipe.

Therefore, in order to remove the cutting bit through the buried pipe in order to replace the cutting bit, it is necessary to reduce the outer diameter of the cutting bit from the time of cutting.

In order to solve the above-mentioned problem, conventionally, for example, although not shown in the drawings, the cutting bits are divided and configured.
When the main shaft is pressurized and rotated forward (cutting), a wedge-like object moves forward to expand the divided bit to the periphery and cut it. Something like retreats and the cutting bit shrinks, so
It can be pulled out and replaced through the buried pipe,
In addition, various attempts have been made, but in any case, the operation of expanding and contracting the cutting bit does not work smoothly. The current situation is that troubles occur frequently and effective means are not provided yet.

[0006]

In view of the above, the enlarging / reducing operation of the cutting bit can be variously designed in view of the design.
It is an object of the present invention to provide a tightly closed structure with no gap for earth and sand to enter.

The present invention solves the above-mentioned problem effectively by providing a sub-bit consisting of a circular portion and a non-circular portion in a main bit of a cutting bit so as to be freely rotatable at a set angle. It is assumed that.

[0008]

That is, the present invention relates to a circular cutting method for drilling and drilling the ground such as drilling and drilling various pipes, which is detachably attached to the tip of a rotating spindle. In hex bits,

The cutting bit has at least one sub-bit centered on an equiangular angle point on a concentric line centered on the center of a circular main bit having a diameter smaller than the inner diameter of the buried pipe, and has at least one sub-bit. The bit is provided so that the set angle rotation can be freely adjusted by switching the main shaft between forward and reverse rotations, and the sub-bit is made up of a truncated circular portion and a circular portion in which a small circular part is cut out,

[0010] During KezuSusumu by forward rotation of the spindle, tighten not position a part of the circle portion and a segmental portion of the sub bit to protrude outwardly of the outer circumferential edge of the main bit, mainly in this state, the sub-bit Preparing to cut in parallel with the main shaft rotation,

When the cutting bit is pulled out and collected, the sub-bit is rotated at the set angle by the reverse rotation of the main shaft at the set angle, and the cutout portion is provided so as to be positioned inside the outer circumferential line of the main bit. The problem is solved by a cutting bit for boring and the like.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. Removably attached to the tip of the rotating spindle 1
In the circular drill bit A for drilling and drilling the ground such as drilling and drilling various pipes,

At least one cutting bit A is set at an equiangular angle point on a concentric line 4 centered on the center of a circular main bit 3 having a diameter smaller than the inner diameter of the buried pipe 2 (steel pipe). And the sub-bit 6 is provided so as to be capable of adjusting the forward / reverse rotation of a set angle (eg, 180 °) by switching the main shaft 1 between forward and reverse rotations. It consists of a cutout part 6b and a circle part 6a in the shape of a notch,

[0014] KezuSusumu time due to the positive rotation of the main shaft 1, occupies not position a part of the circle portion 6a and the segmental portion 6b of the sub-bit 6 protrude outwardly of the outer circumferential line 7 of the main bit 3, this In this state, the main and sub-bits 3 and 6 are prepared so as to be cut in rotation with the forward rotation of the spindle 1,

[0015] During pulling recovering KezuSusumu bits A, set angle (e.g., 15 °) of the main shaft 1 set angle rotation of the sub-bit 6 by a reverse rotation (e.g., 15 °), and the segmental portion 6b of the main bit 3 A cutting bit A for boring or the like is provided so as to be positioned inside the outer circumferential line 7 of FIG.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above-described cutting bit A, the sub-bit 6 is set at a set angle (for example, 15) by forward and reverse rotation of the main shaft 1.
° ) As means to rotate forward and reverse,

For example, a gear 8 is formed on the circumference of the tip of the main shaft 1, and a gear 9 is formed on the inner circumference of the support shaft 5 of the sub-bit 6 facing the gear 8, and the two gears 8, 9 mesh with each other. And the gears between the set arc angles of the gear 9 are cut out to form toothless portions 9a so that the gears 8 and 9 are disengaged between the set arc angles. (FIGS. 2 and 3)

At the time of cutting to rotate the main shaft 1 forward, the gear 8 of the main shaft 1 is disengaged from the toothless portion 9a of the gear 9 of the sub-bit 6 so that the gears 8 and 9 are disengaged from each other, and the circle of the sub-bit 6 is rotated. Part 6a and missing circle
A part of the portion 6b is positioned outside the outer circumferential line 7 of the main bit 3 so that the main and sub bits 3, 6 rotate in the forward rotation direction with the main shaft 1 to perform cutting. (FIGS. 1, 2, 4, and 5)

The reverse rotation of the main shaft 1 at the set angle (for example, 15 ° ) causes the two gears 8 and 9 to mesh with each other, causing the sub-bit 6 to rotate at the set angle (for example, 15 ° ). Are provided inside the outer circumferential line 7 of the main bit 3 so that the cutting bit A can be pulled out and collected through the buried pipe 2. (Fig. 3)

The means for rotating the sub-bit forward / reverse by the forward / reverse rotation of the main shaft is not limited to the above-mentioned gear configuration. For example, a stopper, a cam and the like are relatively attached to the main shaft and the sub-bit support shaft. In other words, when the cutting bit is cut by forward rotation of the spindle, the circular portion of the sub bit
And a part of the missing circle portion protrudes outside the outer circumferential line of the main bit, the sub-bit stops rotating around the support shaft, and the main and sub-bits rotate When the main shaft is rotated at the set angle in the reverse direction, the spindle of the sub-bit rotates at the set angle for the first time, and the missing portion of the sub-bit is located inside the outer circumferential line of the main bit. The specific configuration is arbitrary as long as the drill bit is provided so as to be pulled out and collected through the buried pipe.

As examples of cutting bits for performing normal straight cutting, as shown in FIGS. 1, 2 and 3, the cutting surfaces of the main and sub bits 3 and 6 of the cutting bit A are It is formed at right angles to the center axis 10,

In the case of the cutting bit A in which the cutting direction can be freely controlled by measuring the target provided near the cutting bit A in the course of the straight cutting with the transit on the starting pit side, the cutting of the main bit 3 is performed. The advance surface is formed so as to be inclined at a set angle (for example, about 10 °) with respect to the center axis 11 of the main shaft 1, and the advancing surface when the sub-bit 6 installed on the main bit 3 is abraded is used as the main bit 3.
It is formed with the same inclination. (FIGS. 4 and 5)

When the cutting bit A on the inclined cutting surface is moved forward by the impact of the air hammer 11 or the like while the rotation of the main spindle 1 is stopped, the cutting bit A is inclined without moving straight. The direction of the point 12 of the surface (the point 12 of FIG. 4)
From the point 12 to the lower left and from the point 12 in FIG. 5 to the lower right), the cutting direction can be freely adjusted by advancing the point toward the correction target direction. Can be controlled.

[0024]

When the main shaft 1 is rotated forward, that is, the cutting bit A is rotated forward and cut, and at the same time, the buried pipe 2 is pulled by the cutting bit and buried as shown in FIG. Spindle 1
The rotation of the sub-bit 6 (due to the rotation of the support shaft 5) is stopped in a state where the gear 8 of the sub-bit 6 and the gear 9 of the support shaft 5 of the sub-bit 6 are disengaged at the toothless portion 10, and at the same time, the sub-bit 6 Circle part 6a
And a part of the missing circle portion 6b is located outside the outer circumferential line 7 of the main bit 3. Therefore, when the cutting bit A is driven in the forward rotation, it has the same diameter or a larger diameter as the buried pipe 2. The hole is cut, so that the buried pipe 2 is buried with the cutting of the cutting bit A.

Next, in order to cope with wear and breakage of the cutting bit A and changes in the hardness of the ground, etc., the cutting bit A
When the main shaft 1 needs to be pulled out and collected on the starting pit side for replacement, repair, etc., the main shaft 1 is rotated reversely by a set angle ( 15 ° in the illustrated example), for example, as shown in FIG. , 9 are engaged with each other, and the sub-bit 6 is rotated by a set angle ( 15 ° in the illustrated example) by the rotation of the support shaft 5, so that the missing circle portion 6 b is located inside the outer circumferential line 7 of the main bit 3. The cutting bit A having a smaller diameter than the inner diameter of the buried pipe 2 is pulled out and collected through the buried pipe 2.

When the exchange or repair of the collected cutting bit A is completed, the cutting bit A is returned to the excavation position through the buried pipe 2 and the main shaft 1 is rotated forward again. By the gears 8 and 9 meshed by the rotation operation, the support shaft 5 and the sub-bit 6 are set at a set angle ( 15 in the illustrated example).
° ) The rotation is restored, the gear reaches the toothless portion 9a, the gears 8 and 9 are disengaged from each other, and the sub-bit 6 stops. At the same time, a part of the circular portion 6a and a part of the sub-circle 6b of the sub-bit 6 3, the main and sub-bits 3 and 6, ie, the cutting bit A, are rotated forward by the forward rotation of the main shaft 1 to perform cutting again.

Normally, the cutting operation is performed while measuring the cutting direction of a target provided near the cutting bit with a transit provided on the starting pit side or the like. There are many cases where the wheel is cut away from the target direction due to the above. At that time, as shown in FIGS.
In the case of the cutting bit A in which the cutting surfaces of the main and sub bits 3 and 6 are formed to be inclined, once the forward rotation of the main shaft 1 is once stopped,
The cutting bit A is blown by the air hammer 11 or the like while the tip 12 of the inclined cutting surface of the cutting bit A is directed to the correction target direction (for example, FIG. 4 is inclined downward, and FIG. 5 is inclined right downward). When the cutting bit A advances, the cutting bit A moves forward toward the tip 12 by the resistance guide of the inclined cutting surface, and corrects the cutting direction. Is what you do.

[0028]

[Effect] When the main shaft is rotated forward, the circular bit and the missing circular bit of the sub bit
Stops at a position where a part of the main bit protrudes outside the outer circumferential line of the main bit, and in this state, the main and sub bits, i.e., the cutting bit, can be turned forward and cut, and the main shaft can be set. When the angle reversely rotates, the sub-bit automatically rotates the set angle,
The excellent effect that the cut-out part is located inside the outer circumferential line of the main bit, so that the cutting bit whose diameter is smaller than the inner diameter of the buried pipe can be pulled out and collected through the buried pipe for replacement, repair, etc. There is.

Since a small circular sub-bit is provided so as to be capable of normal and reverse rotation adjustment at each equi-arc angle point on a concentric line centered on the center of the circular main bit, the main bit and the sub-bit can be freely adjusted. It is only necessary to perform the fitting processing of the bit in the tangential state of the circles, so that the processing can be performed precisely and easily, and the auxiliary bit only rotates the set angle within the tangent of the circles. No gap is generated during the rotation operation, and therefore there is no possibility that excavated earth and sand or the like may enter the gap and cause malfunction.

Further, by forming the fronts of the main and sub bits of the cutting bit on the inclined cutting surface, the cutting bit can be corrected and cut in the direction of the tip of the inclined cutting surface. There is an excellent feature that the cutting direction can be freely controlled just by adjusting the position of the part.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of an embodiment of a cutting bit according to the present invention, in which a circular portion of a sub-bit projects outside an outer circumferential line of a main bit and is cut by a forward rotation of a main shaft. FIG.

FIG. 2 is a front view of FIG. 1;

FIG. 3 is a front view of FIG. 1 and shows a setting angle (180 °) of a main shaft.
FIG. 8 is a diagram showing a state in which the missing portion of the sub-bit is positioned inside the outer circumferential line of the main bit by the reverse rotation, and the cutting bit can be pulled out and collected through the buried pipe.

FIG. 4 is a vertical sectional front view of an embodiment in which the fronts of the cutting bits (main and sub bits) are formed to be inclined.

FIG. 5 is an explanatory view showing a state in which a buried pipe (steel pipe) is buried in parallel with the cutting by the cutting bit (FIG. 4) of the present invention.

[Description of Signs] A Cutting bit of the present invention 1 Main shaft 2 Buried pipe (eg, steel pipe) 3 Main bit 4 Concentric line 5 Support shaft 6 Sub bit 6a Circular portion 6b Missing portion 7 Outer circumferential line of main bit 8 Gear (Main shaft) 9 Gear (support shaft) 9a Tooth missing part 10 Center axis of main shaft 11 Air hammer 12 Pointed end 13 Ground

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG. 2

FIG. 3

FIG.

FIG. 4

FIG. 5

Claims (3)

[Claims] 1. A circular cutting bit which is detachably attached to the tip of a rotating spindle to perform drilling and drilling of the ground such as boring and drilling various pipes. With at least one sub-bit around an equi-arc angle point on a concentric line centered on a concentric circle centered on the center of a circular main bit smaller than the inner diameter of the pipe,
The sub-bit is provided so that the rotation of the main shaft can be set at an angle by switching between forward and reverse rotations of the main shaft. At the time of cutting by rotation, a part of the circular portion of the sub-bit is projected outside the outer circumferential edge of the main bit, and the missing portion is positioned toward the center of the main bit. The bit is rotated so that it rotates in the same direction as the main shaft.When the bit is pulled out and collected, the sub-bit is rotated by the set angle of the main shaft and the set angle is reversed. Cutting bits for boring, etc., which are provided so as to be positioned inside the circumferential line. 2. A gear is formed on the circumference of the main shaft, and a gear is formed on the circumference of the support shaft of the sub-bit opposed to the gear so that both gears are meshed with each other. The gear between the arc degrees is cut out to form a toothless portion so that the gears are disengaged between the set arc angles. Is disengaged from the gears of the sub-bit, and the circular portion of the sub-bit is positioned protruding outside the outer circumferential line of the main bit,
The main and sub bits rotate in the same direction as the main shaft to perform cutting, and the two gears mesh by the reverse rotation of the set angle of the main shaft.
The sub-bit is rotated by a set angle so that the missing portion of the sub-bit is positioned inside the outer circumferential line of the main bit so that the cutting bit can be pulled out and collected through the buried pipe. Item 1. A cutting head for boring or the like according to item 1. 3. The cutting surface of the main bit and the sub bit of the cutting bit is formed as a cutting surface perpendicular to the center axis of the main shaft, and the cutting surface of the main bit is inclined at a set angle with respect to the center axis of the main shaft. 2. The cutting bit for boring or the like according to claim 1, wherein the cutting bit is formed by cutting and the cutting surface of the sub-bit installed on the main bit is cut at the same angle as the main bit.