JP5686280B2 - Cutting bit of ground cutting device - Google Patents

Description

The earthing auger provided on the central axis in the steel pipe, the air hammer, and the cutting bit provided at the tip of the air hammer are rotationally driven by a rotating means so that the forward and reverse rotation is possible, and the tip is rotated to the rear end of the cutting bit. A ground pipe comprising a freely connected leading steel pipe and a steel pipe connected to the steel pipe so as to be rotated in a forward / reverse direction by other rotating means, and a crown bit for cutting is provided at the tip of the leading steel pipe In the cutting device of

The cutting bit has a diameter that is slightly smaller than the inner diameter of the steel pipe, and a shaft hole is formed in the front center of the disk having a set thickness to form a flat top surface portion at the upper part of the circumference, and the top surface portion of the disk The right end of the tube is extended to the same plane up to a dimension slightly larger than the outer diameter of the steel pipe to form an extended portion, and the protruding portion protrudes in the same shape as the extended portion on the front side of the extended portion. A plurality of cemented carbide bits are planted on the same plane of the top surface portion, the extending portion, and the projecting portion to provide a rotating bit half, and the two rotating bit halves are used as a pair. Rotating the rotating bit halves of the pair of rotating bit halves together in an inverted symmetrical state in which the top surface part, the extension part and the projecting part of both halves are in the same plane and the shaft holes of both halves communicate with each other While providing a bit

The thickness of the rotating bit is set at the center of the short cylinder of a machined bit body, which is mounted on the upper end of an air hammer and protrudes from a short cylinder on a disk that can be moved up and down in the steel pipe. A fitting groove having an appropriate width is recessed, and the bottom portion of the fitting groove is formed in an arcuate arc surface corresponding to the circumference centering on the shaft hole of the rotating bit, and both sides of the rotating bit are fitted. The shaft is inserted into the shaft hole of the rotating bit and the short cylinder while the lower surface is in close contact with the circular arc surface, and the rotating bit is axially supported on the short cylinder, and each rotation thereof. Each extending part and projecting part of the bit half body is provided with a set angle rotatable upward, and is configured.

A state where each top surface portion, extending portion, and projecting portion of the rotating bit are in the same plane, that is, a circular locus drawn by the tip of each extending portion of each rotating bit half is larger than the outer diameter of the steel pipe. In a state, the cutting bit is rotationally driven to prepare a hole having a diameter larger than the outer diameter of the steel pipe,
In addition, the lower surface of each rotating bit half of the rotating bit is in close contact with the circular arc surface, and each extending portion and projecting portion of each rotating bit half is rotated upward by a set angle and positioned inside the inner diameter of the steel pipe That is, the circular locus drawn by the tip of each extending part of each rotating bit half is smaller than the inner diameter of the steel pipe, and the cutting bit is pulled back into the steel pipe / starting pit, or the cutting bit is put into the steel pipe. It is equipped so that the cutting with the crown bit in the state pulled back to can be performed freely.
Accordingly, there is provided a cutting bit of a ground cutting device characterized in that various grounds, objects and the like can be freely drilled, drilled, and steel pipes can be freely embedded.

When embedding water and sewage, gas, electricity / telephone lines, and other various pipes in the ground, especially in urban areas, the ground surface, roads, etc. should not be excavated and road traffic blocked. Therefore, usually, a starting vertical pile is provided on the side of a road, etc., and a cutting device is installed in the shaft, and the cutting is buried.

However, in the case of using a cutting device by turning a cutting bit and hitting with an air hammer or a vibration load by a vibration generating device, there is not much problem in cutting normal ground, but for example, soft ground, bedrock, sand layer , Cobblestone layers, alternate layers of the ground, pine piles, concrete piles, liner plates, steel and other buried objects in the ground, and also hit existing human holes (eg manholes, fume pipes, etc.) If this happens, or if branch pipes are installed in existing pipes, manholes, etc., there are issues that are difficult to handle with this crushing type cutting device. In such cases, a crown bit is attached to the leading steel pipe. , It is more suitable to cut with the crown bit, but conventionally, when switching from crushing and cutting with the cutting bit to cutting with the crown bit, A lot of maneuvers are required because the bit, air hammer, auger, etc. and all steel pipes have to be pulled back to the start pit, or the drill bit etc. must be removed by cutting from the ground side to the position of the drill bit. It was time consuming and extremely inefficient.

JP 2001-32666 Japanese Patent Application No. 2009-274945

Therefore, the present invention comprises a rotating means of a cutting bit as a cutting means by a crushing method and a striking means of an air hammer, and a rotating means of a steel pipe attached with a crown bit as a cutting means by a cutting method, etc. It is intended to provide a cutting device that can be used according to the purpose.
That is, as the cutting bit used in the cutting device, when the crushing method is used, each top surface portion, the extending portion and the protruding portion of the rotating bit are in the same plane, that is, each rotation. With the circular locus drawn by the extended part of the bit half body and the tip of the protruding part larger than the outer diameter of the steel pipe, the cutting bit is driven to rotate to drill a hole having a diameter larger than the outer diameter of the steel pipe. In addition, if necessary, the lower surface of each rotating bit half of the rotating bit is brought into close contact with the circular arc surface, and each extending portion and projecting portion of each rotating bit half are rotated upward by a set angle. In the state where it is located inside the inner diameter of the steel pipe, that is, the circular trajectory drawn by the extended part of each rotating bit half and the tip of the protruding part is smaller than the inner diameter of the steel pipe, and the inside and start of the cutting bit Pull back into the mine (replacement repair, etc.) or with the cutting bit pulled back into the steel pipe So as to perform a cutting method KezuSusumu by bits freely,
The present invention provides a cutting bit according to the present invention that can be easily switched to these means, and as described above, makes it possible to cut any ground that is difficult with conventional means, thereby solving the problem.

That is, the present invention is configured to rotationally drive the earthing auger provided on the central axis in the steel pipe, the air hammer, and the cutting bit provided at the tip of the air hammer so as to be able to rotate forward and backward by a rotating means, and the tip of the cutting is provided. A leading steel pipe that is rotatably connected to the rear end of the bit and a steel pipe connected thereto are rotatably driven by other rotating means so that the forward and reverse rotation is possible. A crown bit for cutting is provided at the tip of the leading steel pipe. In the ground cutting device that is equipped,

The cutting bit has a diameter that is slightly smaller than the inner diameter of the steel pipe, and a shaft hole is formed in the front center of the disk having a set thickness to form a flat top surface portion at the upper part of the circumference, and the top surface portion of the disk The right end of the tube is extended to the same plane up to a dimension slightly larger than the outer diameter of the steel pipe to form an extended portion, and the protruding portion protrudes in the same shape as the extended portion on the front side of the extended portion. Installing a plurality of cemented carbide bits on the same plane of the top surface portion, the extending portion and the protruding portion to provide a rotating bit half body,

The two rotating bit halves form a pair, and the rotating bit halves of the pair of rotating bit halves are in the same plane with the top surface portion, the extending portion, and the projecting portion of both halves. While providing a rotating bit in combination with an inverted symmetrical state in which the axial holes of the body communicated,

The thickness of the rotating bit is set at the center of the short cylinder of a machined bit body, which is mounted on the upper end of an air hammer and protrudes from a short cylinder on a disk that can be moved up and down in the steel pipe. A fitting groove having an appropriate width is recessed, and the bottom portion of the fitting groove is formed in an arcuate arc surface corresponding to the circumference centering on the shaft hole of the rotating bit, and both sides of the rotating bit are fitted. The shaft is inserted into the shaft hole of the rotating bit and the short cylinder while the lower surface is in close contact with the circular arc surface, and the rotating bit is axially supported on the short cylinder, and each rotation thereof. The problem is solved by the cutting bit of the ground cutting device, characterized in that each extending portion and protruding portion of the bit half body are provided so as to freely rotate at a set angle upward.

When cutting sewage, gas, water supply, electric pipes, cobblestones, bedrock layers, etc., while crushing cobblestones, bedrock layers, etc. with crushing bit by crushing bit by impact of air hammer, change of soil, burial Depending on the type of object, crushing by impact may not be possible.
Conventionally, in such a case, the pipe in the middle of cutting was pulled out or dug out from the surface side,
In the present invention, when the cutting means by crushing method, the top surface portion of the cutting bit body of the cutting bit and each front bit portion of the pair of expansion and contraction bit halves are aligned to cut larger than the diameter of the steel pipe, A pair of expansion / contraction bit halves are slid forward, only the front bit portions of the pair of expansion / contraction bit halves are aligned and adjusted to be smaller than the diameter of the steel pipe, and the cutting bit is pulled back into the steel pipe,
As it is provided so that it can be easily switched to a means for exchanging and repairing a cutting bit, an air hammer, etc., or a cutting method by a cutting method using a steel pipe crown bit, etc. By properly using the means, there is an excellent effect that it can be freely and extremely efficiently adapted to the various grounds, objects, etc. as described above, or changes in soil quality, types of buried objects, and the like.

The cutting bit, air hammer, etc. can be pulled back to the starting pit through the steel pipe and the steel pipe can be emptied, so the hollow of the cutting steel pipe can be used to attach the branch pipe to the existing pipe, and the cutting direction Can be easily measured and corrected.

  FIG. 1 is a partially cut front view and a plan view of a cutting bit or the like according to an embodiment of the present invention and a leading steel pipe portion provided in an example of a ground cutting device. Example 1   FIG. 2 is a partially cut right side view of FIG.   FIG. 3 shows the extension of each rotating bit half by the sliding guide of the inner peripheral edge of the crown bit of the steel pipe and the lower surface of each rotating bit half by pulling back the cutting bit of FIG. 1 in the direction of the steel pipe. It is explanatory drawing of the state which pulls back a cutting bit in a steel pipe as a state which rotated the setting part and the projecting part upward by the set angle, and was located inside the inner diameter of the steel pipe. Example 1   FIG. 4 is a front view, a plan view, a bottom view, a right side view, and a left side view of the rotating bit. Example 1   FIG. 5 is a front view, a plan view, a rear view, a bottom view, a right side view, and a left side view of the rotating bit half body. Example 1   FIG. 6 is a front view, a plan view, and a partially cut right side view of the cutting bit body. Example 1   FIG. 7 is a diagram showing a schematic configuration of an example of a ground cutting device using the cutting bit of the present invention.

In the ground cutting device, the cutting bit 1 is provided with a rotating bit half 7 having a top surface portion 10, an extending portion 11 and a projecting portion 12 in the same plane, and a pair of rotating bit halves 7. The rotating bit halves 7 are combined in an inverted symmetrical state in which the top surfaces, the extending portions, and the projecting portions of both halves 7 and 7 are in the same plane, and the shaft holes of both halves 7 and 7 are in communication. While the rotating bit 6 is provided, the rotating bit 6 is pivotally supported by the supporting shaft 20 in the fitting groove 17 of the short cylinder 16 of the cutting bit body 14 attached to the upper end portion of the air hammer 4, and each of the rotating bit halves is provided. A grounding bit of a ground grinding device, characterized in that each extending part and projecting part are provided so as to be rotatable upward by a set angle.
The specific shapes of the cutting bit body, the rotating bit, and the rotating bit half body in the cutting bit of the present invention are not limited to the illustrated examples, and the shape having the same configuration, function, and effect as those of the embodiment. Is included.

FIG. 7 is a diagram showing a schematic configuration of an example of a ground cutting device using the cutting bit of the present invention.

An example of a ground cutting device using the cutting bit of the present invention is a soil auger 5 provided on a central axis in a steel pipe 2, an air hammer 4, and a cutting bit 1 provided at the tip of the air hammer 4. The leading steel pipe 2 whose tip is rotatably connected to the rear end of the cutting bit 1 and the steel pipe 2 connected to the leading steel pipe 2 are rotatably driven forward and backward by another rotating means B. And a crown bit 3 for cutting is provided at the tip of the leading steel pipe 2. (Fig. 7)

In FIG. 7, A is a rotating means, B is a rotating means, C is a central axis, 21 is a mounting plate, 22 is a ground, 23 is a motor, 24 is a gear, 25 is a discharge hole, 26 is a propulsion base, and 27 is The base, 28 is a propulsion means, 29 is a transit, 30 is a target, and 31 is a start pit.

FIG. 1 is a partially cut front view and plan view of a cutting bit and the like of the embodiment of the present invention prepared in one example of a ground cutting device and a steel pipe portion at the top,
2 is a partially cut right side view of FIG.
FIG. 3 shows the extension of each rotating bit half by the sliding guide of the inner peripheral edge of the crown bit of the steel pipe and the lower surface of each rotating bit half by pulling back the cutting bit of FIG. 1 in the direction of the steel pipe. An explanatory diagram of a state in which the cutting bit is pulled back into the steel pipe as a state in which the part and the projecting part are rotated upward by a set angle and positioned inside the inner diameter of the steel pipe,
FIG. 4 is a front view, a plan view, a bottom view, a right side view, and a left side view of the rotating bit,
FIG. 5 is a front view, a plan view, a rear view, a bottom view, a right side view, and a left side view of the half of the rotating bit.
FIG. 6 is a front view, a plan view, and a partially cut right side view of the cutting bit body.

In the ground grinding device, the present invention provides the grinding bit 1 with a shaft hole 9 in the center of the front surface of the disk 8 having a diameter slightly smaller than the inner diameter of the steel pipe 2 and a set thickness, and is flat on the upper part of the circumference. And the right end of the top surface portion 10 of the disc 8 is extended to the same plane up to a slightly larger dimension than the outer diameter of the steel pipe 2 to form the extending portion 11, A projecting portion 12 is formed by projecting the front side of the extending portion 11 in the same shape as the extending portion 11, and the top surface portion 10, the extending portion 11, and the projecting portion 12 are on the same plane. A number of bits 13 are planted to provide a rotating bit half 7 (FIG. 5).

The two rotating bit halves 7 are paired, and the rotating bit halves 7 of the pair of rotating bit halves 7 are connected to each other by a top surface portion, an extending portion, and a projecting portion of both halves 7, 7. The rotating bit 6 is provided in combination with an inverted symmetrical state in which the axial holes of both halves 7 and 7 are in communication with each other (FIG. 4).

The rotating bit body 14 is mounted at the upper end portion of the air hammer 4 and is provided with a short cylinder 16 projecting from a circular base 15 provided in the steel pipe 2 so as to be movable up and down. The fitting groove 17 having a width corresponding to the thickness dimension of the bit 6 is recessed, and the bottom of the fitting groove 17 is an arcuate arcuate surface corresponding to the circumference around the shaft hole 9 of the rotating bit 6. 19 (FIG. 6)

With the both sides of the rotating bit 6 closely fitted in the fitting groove 17 and the lower surface in close contact with the arcuate surface 19, the support shaft 20 is inserted into the shaft hole 9 of the rotating bit 6 and the shaft hole 18 of the short cylinder 16. The rotating bit 6 is pivotally supported on the short cylinder 16 and the extending portions 11 and projecting portions 12 of the rotating bit halves 7 and 7 are provided to be rotatable upward by a set angle. It is a cutting bit of a ground cutting device, characterized in that
(Fig. 1 and Fig. 2)

At the time of cutting by the crushing method, the top surface portion 10, the extending portion 11 and the projecting portion 12 of the rotating bit 6 are in the same plane, that is, the extending portions of the rotating bit halves 7, 7. With the circular locus drawn by the tips of the portion 11 and the projecting portion 12 being larger than the outer diameter of the steel pipe 2, the cutting bit 1 is driven to rotate to drill a hole having a diameter larger than the outer diameter of the steel pipe 2. (Figure 1)

Further, at the time of cutting means by the cutting method or at the time of replacement repair, the lower surfaces of the rotating bit halves 7 and 7 of the rotating bit 6 are brought into close contact with the arcuate surface 19 and the extending portions 11 of the rotating bit halves 7 and 7 are connected. And the state where the projecting portion 12 is rotated upward by a set angle and located inside the inner diameter of the steel pipe 2, that is, the circles drawn by the extending portions 11 of the rotating bit halves 7 and 7 and the tips of the projecting portions 12 are drawn. In a state where the trajectory is smaller than the inner diameter of the steel pipe 2 and the cutting bit 1 is pulled back into the steel pipe 2 and the start shaft 31 (replacement repair, etc.), or the cutting bit 1 is pulled back into the steel pipe 2 This is a cutting bit of a ground cutting device that is configured so that cutting with the crown bit 3 can be performed freely and can be easily switched to both means. (Fig. 1, Fig. 3)

Means for rotating the extending portions 11 and the projecting portions 12 of the rotating bit halves 7 and 7 of the rotating bit 6 upward by a set angle to pull the cutting bit 1 back into the steel pipe 2 in more detail. To explain
When the cutting bit 1, the air hammer 4, the earth discharging auger 5, etc. are pulled back in the direction of the starting pit 31 by the propulsion means 28, the lower surfaces of the rotating bit halves 7, 7 of the cutting bit body 14 are made of the steel pipe 2. Colliding with the inner peripheral edge of the upper end of the crown bit 3, the extending portions 11 and the projecting portions 12 of the rotating bit halves 7, 7 are rotated upward by a set angle by the sliding guide to be inside the inner diameter of the steel pipe 2. In other words, the circular locus drawn by the ends of the extending portions 11 and the protruding portions 12 of the rotating bit halves 7 and 7 is smaller than the inner diameter of the steel pipe 2. It is pulled back into the steel pipe 2. (FIGS. 1-3, 7)

"Mechanism for crushing"
The rotating means B is operated to rotate the earth discharging auger 5, the air hammer 4, and the cutting bit 1 (the top surface portion 10, the extending portion 11 and the protruding portion 12 of the rotating bit 6 are in the same plane). At the same time, the rotating means A is operated to reversely rotate the mounting plate 21 and the steel pipe 2, and the ground 22 is crushed by the impact force of the cutting bit 1 by the air hammer 4 at the same time as the cutting bit 1 rotates. Then cut down (23 for motor, 24 for gear),

The soil generated by excavation is introduced into the steel pipe 2 from the soil removal hole of the cutting bit 1 and transferred rearward by the soil auger 5 to be discharged to the outside from the rear discharge hole 25 of the steel pipe 2 at the rear end. The reverse rotation of 2 assists the earth removal transfer action of the earth removal auger 5,

Further, along with the advancement of the cutting bit 1, the forward impact force is received by the crown bit 3 from the flange of the cutting bit 1, the front steel pipe 2 is pulled forward, and the steel pipe 2 and the mounting plate 21 connected thereto are advanced together. . (FIGS. 1-3, 7)

"Machining means by cutting method"
Further, depending on the ground conditions, the cutting bit 1 is rotated inside the inner diameter of the steel pipe 2 by rotating the extending portions 11 and the projecting portions 12 of the rotating bit halves 7 and 7 of the rotating bit 6 upward by a set angle. After being pulled back into the leading steel pipe 2, the crown bit 3 is rotated to perform cutting.

In synchronism with the cutting of the cutting bit 1 and the advance of the steel pipe 2, the base 27 on the propulsion base 26 is further pressurized and propelled by the propulsion means 28 such as a hydraulic cylinder, so The condition ground 22 is advanced to embed the steel pipe 2. (FIGS. 1-3, 7)

By properly using the “crushing method by means of crushing” and “retracting means by means of cutting method or by pulling back for replacement repair”, all adverse conditions such as ground of rock, cobblestone, gravel, ground under water, etc. Ground cutting can be performed very efficiently.
The ground cutting device is not limited to the embodiment device, and can be widely used for a device having an equivalent function and capable of using the cutting bit of the present invention.
The specific shapes of the cutting bit body, the rotating bit, and the rotating bit half in the cutting bit of the present invention are not limited to the illustrated examples, but include shapes having the same configuration, operation, and effect as those. It is a waste.

A Rotating means B Rotating means C Center axis 1 Cutting bit 2 Steel pipe 3 Crown bit 4 Air hammer 5 Earthing auger 6 Rotating bit 7 Rotating bit half 8 Disc 9 Shaft hole 10 Top surface portion 11 Extending portion 12 Projecting portion 13 Bit 14 Cutting bit body 15 Circular base 16 Short cylinder 17 Fitting groove 18 Bottom 19 Arc surface 20 Support shaft 21 Mounting plate 22 Ground 23 Motor 24 Gear 25 Discharge hole 26 Propulsion base 27 Base 28 Propulsion means 29 Transit 30 Target 31 Starting pit

Claims (2)

The earthing auger provided on the central axis in the steel pipe, the air hammer, and the cutting bit provided at the tip of the air hammer are rotationally driven by a rotating means so that the forward and reverse rotation is possible, and the tip is rotated to the rear end of the cutting bit. A ground pipe comprising a freely connected leading steel pipe and a steel pipe connected to the steel pipe so as to be rotated in a forward / reverse direction by other rotating means, and a crown bit for cutting is provided at the tip of the leading steel pipe In the cutting device of
The cutting bit has a diameter that is slightly smaller than the inner diameter of the steel pipe, and a shaft hole is formed in the front center of the disk having a set thickness to form a flat top surface portion at the upper part of the circumference, and the top surface portion of the disk The right end of the tube is extended to the same plane up to a dimension slightly larger than the outer diameter of the steel pipe to form an extended portion, and the protruding portion protrudes in the same shape as the extended portion on the front side of the extended portion. A plurality of cemented carbide bits are planted on the same plane of the top surface portion, the extending portion, and the projecting portion to provide a rotating bit half, and the two rotating bit halves are used as a pair. Rotating the rotating bit halves of the pair of rotating bit halves together in an inverted symmetrical state in which the top surface part, the extension part and the projecting part of both halves are in the same plane and the shaft holes of both halves communicate with each other While providing a bit
The thickness of the rotating bit is set at the center of the short cylinder of a machined bit body, which is mounted on the upper end of an air hammer and protrudes from a short cylinder on a disk that can be moved up and down in the steel pipe. A concave groove having an appropriate width is provided, and the bottom of the fitting groove is formed into an arcuate arc surface corresponding to the circumference centered on the shaft hole of the rotating bit,
With both surfaces of the rotating bit closely fitted in the fitting groove and the lower surface in close contact with the arcuate surface, the support shaft is inserted into the shaft hole of the rotating bit and the short cylinder, and the rotating bit is inserted into the short cylinder. It is supported by a shaft, and each of the extending portions and projecting portions of the rotating bit halves are provided so as to be freely rotatable at a set angle upward.
Cutting bit of ground cutting device. The earthing auger provided on the central axis in the steel pipe, the air hammer, and the cutting bit provided at the tip of the air hammer are rotationally driven by a rotating means so that the forward and reverse rotation is possible, and the tip is rotated to the rear end of the cutting bit. A ground pipe comprising a freely connected leading steel pipe and a steel pipe connected to the steel pipe so as to be rotated in a forward / reverse direction by other rotating means, and a crown bit for cutting is provided at the tip of the leading steel pipe In the cutting device of
The cutting bit has a diameter that is slightly smaller than the inner diameter of the steel pipe, and a shaft hole is formed in the front center of the disk having a set thickness to form a flat top surface portion at the upper part of the circumference, and the top surface portion of the disk The right end of the tube is extended to the same plane up to a dimension slightly larger than the outer diameter of the steel pipe to form an extended portion, and the protruding portion protrudes in the same shape as the extended portion on the front side of the extended portion. A plurality of cemented carbide bits are planted on the same plane of the top surface portion, the extending portion, and the projecting portion to provide a rotating bit half, and the two rotating bit halves are used as a pair. Rotating the rotating bit halves of the pair of rotating bit halves together in an inverted symmetrical state in which the top surface part, the extension part and the projecting part of both halves are in the same plane and the shaft holes of both halves communicate with each other While providing a bit
The thickness of the rotating bit is set at the center of the short cylinder of a machined bit body, which is mounted on the upper end of an air hammer and protrudes from a short cylinder on a disk that can be moved up and down in the steel pipe. A fitting groove having an appropriate width is recessed, and the bottom portion of the fitting groove is formed in an arcuate arc surface corresponding to the circumference centering on the shaft hole of the rotating bit, and both sides of the rotating bit are fitted. In a state where the lower surface is in close contact with the arcuate surface while closely fitting in the groove,
The support shaft is inserted into the shaft hole of the rotating bit and the short cylinder, and the rotating bit is axially supported on the short cylinder, and each extending portion and projecting portion of each rotating bit half body can be rotated upward by a set angle. Prepared and configured,
Each top surface portion of the rotating bit, the extending portion and the projecting portion are coplanar, and the cutting bit is rotationally driven to cut a hole having a diameter larger than the outer diameter of the steel pipe,
In addition, the lower surface of each rotating bit half of the rotating bit is in close contact with the circular arc surface, and each extending portion and projecting portion of each rotating bit half is rotated upward by a set angle and positioned inside the inner diameter of the steel pipe As a feature, the cutting bit can be pulled back into the steel pipe / start shaft, or the cutting bit can be pulled back into the steel pipe so that the cutting with the crown bit can be performed freely.
A cutting bit of the ground cutting device according to claim 1.

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