JP3160234B2 - Shield machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield excavator used in a propulsion method for burying a sewer underground.

[0002]

2. Description of the Related Art In a method of propelling sand and gravel layers, a method of crushing the gravel and boulders and then transporting them to the ground via a buried pipe is basically adopted. Initially, a shield excavator that excavated the ground used a method in which gravels and cobblestones were guided to a crusher equipped in the shield excavator and crushed.

However, this method has a disadvantage that the crushing efficiency is deteriorated when the amount of gravel or cobblestone in the ground increases. In addition, when the crushing time is long, there has been a problem that sand and the like in the ground are excessively taken in during the crushing time, which causes sinking of the surrounding ground. To solve the above problem, FIG.
A cone type excavator as shown in FIG.
That is, a cutter disk for excavating earth and sand is equipped at the tip of a cylindrical outer shell having a cone guide whose inner diameter decreases toward the rear, and an inner cone that rotates in the cone guide is fixed to the back of the cutter disk. Every
A shield excavator that forcibly rotates the inner cone to sandwich earth and sand in a narrow gap formed at the rear end between the cone guide and the inner cone and efficiently crushes gravel has been developed and used.

In the shield excavator having the above structure, gravel and boulders taken into the excavator from an intake penetrating through the cutter disk are sequentially sent rearward by rotation of the inner cone, and the cone guide and the inner cone are connected to each other. And is efficiently crushed by being caught in the narrow gap. The crushed gravels and cobblestones are transported backward together with other earth and sand, water, etc., and are discharged. As a method of transporting the sediment and gravel, a method such as fluid transport or pneumatic transport is employed.

[0005]

Generally, it is rare that a uniform gravel layer or cobble layer is continuous, and sand layers and clay layers are alternately layered. Many. Since the cone type excavator described above was developed for the purpose of crushing gravels and cobblestones, when encountering different soil qualities such as the sand layer described above, especially a clay layer, the narrow gap between the cone guide and the inner cone There is a problem that the clay is gradually compacted and the gap is closed. If the gap is closed, it becomes difficult to excavate. Therefore, much time is required to remove the closed earth and sand, which has caused delay in the propulsion work.

Another problem is that highly viscous soil adheres to the outer peripheral surface of the inner cone and solidifies, so that it is difficult for the earth and sand to move backward along the outer peripheral surface of the inner cone smoothly. In some cases, crushing of gravels and cobblestones may be difficult. An object of the present invention is to enable good excavation work even in a condition where excavation is difficult with a conventional cone-type excavator, such as an alternating layer of gravel or cobblestone layer and clay layer. A more specific problem is to make it difficult for the gap between the cone guide and the inner cone to be closed by earth and sand. Another problem is to prevent adhesion and solidification of earth and sand to the inner cone.

[0007]

A shield excavator according to the present invention excavates a ground by using an excavator, while propelling a buried pipe connected to the back of the excavator together with the excavator to bury the buried pipe. A shield excavator for a construction method, comprising a cutter disk, a cone guide, and an inner cone.

[0008] The cutter disk is rotatably disposed in front of the excavator, and excavates the ground. The cone guide is disposed behind the cutter disc inside the excavator, has a conical shape whose inner diameter decreases toward the rear, and the earth and sand excavated by the cutter disc is fed into the inner space. The inner cone is rotatably arranged behind the cutter disc inside the cone guide, has a conical shape whose outer diameter increases toward the rear, and has a small crushing gap between the inner cone and the cone guide at the rear end. , Crush the earth and sand in the crushing gap.

A plurality of notches may be provided at least one of the inner circumference of the cone guide and the outer circumference of the inner cone facing each other at the crushing gap at intervals in the circumferential direction. Notch dimensions are 40-60m wide
m and a depth of 40 to 60 mm. A spiral build-up can be provided on the outer peripheral surface of the inner cone.

[0010] An advance / retreat mechanism for moving the inner cone back and forth can be provided. A cleaning liquid supply unit that opens on the inner periphery of the cone guide facing the crushing gap and supplies the cleaning liquid to the crushing gap can be further provided. The excavator further includes a mud feeding pipe that opens to the inner peripheral surface of the cone guide and supplies muddy water to the back of the cutter disk, and the cleaning liquid supply unit can use a part of the muddy water as a cleaning liquid.

A specific configuration will be described. [Basic structure of excavator] The basic structure of the excavator may be the same as that of a normal cone type excavator. The shapes and structures of the cutter disk, cone guide, and inner cone may be the same as those of a normal excavator.

[0012] In addition to the above structure, the excavator includes a discharging pipe for transporting the excavated earth and sand backward, a direction correcting jack for changing the propulsion direction of the excavator, a driving device such as a motor, and a rotation of the driving device. A transmission mechanism such as a speed reducer for transmitting to the cone and the cutter disk, a control line for controlling a driving device and a direction correcting jack, and a supply pipe for electric power and hydraulic pressure can be provided.

[0013] The cutter disk is provided with excavating means such as a cutter and a bit on the front surface thereof, and is provided with an inlet for feeding excavated earth and sand to the rear side. The arrangement structure of the crushing gap formed between the cone guide and the inner cone may be basically the same as that of a normal excavator. The size of the crushing gap varies depending on the soil properties of the ground and the capability of the excavator, but is usually set in the range of several mm to several tens of mm. Preferably 15-30 mm
Set to about.

The excavator may be provided with a feeding and discharging mechanism. The mud feeding and discharging mechanism is a technique for improving the conveying efficiency of excavated sediment by mixing mud with soil excavated by a cutter disk and discharging the soil together with the mud. The basic structure of the feeding and discharging mechanism may be the same as that of a normal feeding and discharging device. As a part of the mud feeding and discharging mechanism, a mud feeding pipe that opens to the inner peripheral surface of the cone guide and supplies muddy water to the back of the cutter disk can be provided. The same structure as that of a normal mud-feeding excavator can be adopted as the mud-pipe and its attached structure.

As a mechanism for discharging the excavated earth and sand, various fluid transport mechanisms and pneumatic transport mechanisms can be provided in addition to the above-mentioned feeding and discharging mechanism. [Notch] The shape and arrangement of the notch are not particularly limited as long as the intended function can be exhibited. In particular,
It is composed of a semicircle, a U-shape, a rectangle, a V-shape and the like. A plurality of notches are arranged at predetermined intervals in the circumferential direction. They may be arranged at equal intervals or may be arranged at irregular intervals.

The notch can be provided on one or both of the inner periphery of the cone guide and the outer periphery of the inner cone. When notches are provided in both the cone guide and the inner cone, their shapes and dimensions may be the same or different. If notches are provided in both the cone guide and the inner cone, and the intervals are equal, if the notches of the cone guide and the inner cone match all around, if you bite gravel etc. into many notches, There is a concern that excessive resistance may be generated, hindering rotation of the inner cone or damaging the device. Therefore, in such a case, it is preferable to make the intervals of the notches partly or entirely unequal.

The size of the notch varies depending on the soil properties of the ground, the construction conditions of the propulsion method, and the like.
It is preferable to set 0 mm and a depth of 40 to 60 mm.
However, when notches are provided in both the cone guide and the inner cone, the depths of both notches may be summed and set in the above range. Further, the preferable size of the notch changes depending on the size of the crushing gap formed between the inner cone and the cone guide.

Due to the configuration of the notch, the crushing gap formed between the cone guide and the inner cone has a regular continuous narrow gap in the circumferential direction and a partially wide gap at the location of the notch. They will be arranged alternately. Earth and sand such as clay compacted or fixed in the crushing gap is likely to separate from the surfaces of the cone guide and the inner cone due to intermittent changes in the gap. With the rotation of the inner cone, the position of the narrow gap and the position of the wide gap are sequentially shifted, so that the above-mentioned separation of the earth and sand is favorably performed over the entire circumference of the crushing gap. Also, if the gravels or boulders enter a wide gap and then the gap becomes narrow, the gravels or boulders are crushed in the narrow gap. The edge of the notch collides with gravels and cobblestones to cause crushing. The crushing gap having the notch improves the bite of the gravel, thereby improving the crushing efficiency. [Spiral build-up] It is formed along the conical outer peripheral surface of the inner cone using a technique such as so-called build-up welding. The protrusion height and width of the overlay may be the same as those of a normal overlay. The spiral may be a single spiral or a plurality of spirals.

Preferably, the direction of the helix is set so that the rotation direction of the inner cone and the turning direction when the helix is traced backward are reversed. With this configuration, the earth and sand existing on the outer periphery of the inner cone are sequentially sent toward the rear crushing gap in accordance with the spiral direction of the spiral build-up with the rotation of the inner cone. When the inner cone performs forward and reverse rotation, it is preferable that the inner cone be adjusted to the rotation direction during normal operation.

The provision of the spiral build-up facilitates the backward movement of the earth and sand. In addition, there is also an effect that gravels and boulders contained in the earth and sand are crushed by contacting or colliding with the spiral build-up during the backward movement. [Advancing / Retracting Mechanism] If the inner cone on the inner periphery can be moved back and forth with respect to the cone guide on the outer periphery, an advancing / retracting mechanism in a normal mechanical device can be adopted.

The cutter disk can be moved forward and backward together with the inner cone. As a specific structure of the advance / retreat mechanism, a reducer and a driving device that rotationally drive the inner cone together with the inner cone are slidably supported by a boss fixed to a partition of the excavator, and a jack fixed to the partition. The inner cone and the like can be integrally moved back and forth by the above operation. As another method, a jack mechanism for moving the inner cone forward and backward may be provided on the rotation shaft portion of the inner cone.

By moving the inner cone forward and backward, the distance between the narrow crushing gaps formed between the cone guide and the inner cone changes. As a result, even if earth and sand adhere to the crushing gap and become closed, the closing can be released. Further, if the crushing gap can be changed, it becomes difficult for earth and sand to adhere to the crushing gap. The interval of the crushing gap or the position of the inner cone can be adjusted according to the soil quality. [Cleaning liquid supply mechanism] The cleaning liquid may be ordinary industrial water, groundwater discharged from the ground, or muddy water for mud feeding.

The specific arrangement structure of the opening of the cleaning liquid supply means is not particularly limited as long as the cleaning liquid can be efficiently supplied to the crushing gap. If the excavator has a mud feed mechanism,
Part of the muddy water used in the mud feeding mechanism can be used as a washing liquid. By supplying the cleaning liquid to the crushing gap, it is possible to wash away the earth and sand that has closed or fixed the crushing gap. The flow of earth and sand passing through the crushing gap becomes smooth.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A shield machine 1 shown in FIGS. 1 and 2 is a machine for gravel ground having a nominal diameter of 1000,
Various mechanical structures are housed inside the outer shell 2 having a cylindrical shape as a whole. The outer diameter of the excavator 1 is set to 1230 mm. At the tip of the excavator 1, a disk-shaped cutter disk 4
It has. The cutter disk 4 is rotationally driven by a drive unit 11 and a speed reducer 10 arranged inside and behind the excavator 1. A plurality of excavating bits or cutters are arranged on the front surface of the cutter disk 4 and excavate the ground as the cutter disk 4 rotates. Although not shown,
An earth and sand intake port penetrates through the cutter disk 4, and the excavated earth and sand is sent into the space behind the cutter disk 4 from the earth and sand intake port.

A cone guide 3 having a conical shape whose inside diameter gradually decreases rearward is provided on the inner periphery of the outer shell 2 of the excavator 1 behind the cutter disk 4. Drilling machine 1
A muddy water space 32 having a triangular cross section is provided between the cylindrical outer shell 2 and the inner surface of the cone guide 3. The muddy water space 32 is provided in the muddy water space 32 from behind the excavator 1. 31
Is connected and muddy water is fed. The muddy water supply port 34 penetrates through the inner surface of the cone guide 3, and feeds the muddy water in the muddy water space 32 into a space between the inside of the cone guide 3 and the back surface of the cutter disk 4. The muddy water facilitates excavation of the ground by the cutter disk 4 and facilitates the operation of discharging the excavated earth and sand to the rear of the excavator 1. Inside the excavator 1, a mud pipe 12 for discharging earth and sand and muddy water backward is installed.

An inner cone 5 is arranged inside the cone guide 3 and behind the cutter disc 4. The inner cone 5 is mounted between the cutter disk 4 and the drive unit 11 and the speed reducer 10, and is driven to rotate together with the cutter disk 4. The shape of the inner cone 5 is a conical shape whose diameter increases rearward. On the outer peripheral surface of the inner cone 5, overlaid portions 13 are arranged vertically and horizontally along the circumferential direction and the ridge direction. Overlay 13
Is formed using a so-called overlay welding technique.

Between the outer periphery of the rear end of the inner cone 5 and the inner periphery of the rear end of the cone guide 3, there is a small crushing gap 6 of about 15 to 20 mm. A muddy water discharge port 36 is opened at a location facing the crushing gap 6 on the inner peripheral surface of the cone guide 3. Part of the mud supplied to the mud space 32 is
6 is discharged toward the crushing gap 6.

As shown in detail in FIG. 2, cutouts 8 having a U-shaped cross section are arranged at equal intervals along the circumferential direction on the outer periphery of the rear end of the inner cone 5. The dimensions of the notch 8 are 50 mm in width and 60 mm in depth. Therefore, at the location of the notch 8, the crushing gap 6 at the location where there is no notch 8 is provided.
A gap 7 wider than that is open. The earth and sand sent to the back of the cutter disk 4
While moving backward in the tapered space formed by the inner peripheral surface of the inner cone 5 and the outer peripheral surface of the inner cone 5, the inner cone 5 is stirred and crushed as the inner cone 5 rotates. At that time, the mud pipe 3
By mixing the muddy water fed from 1 with stirring, the lump of earth and sand collapses and becomes fine and easily moved. The built-up portion 13 arranged on the outer peripheral surface of the inner cone 5 has an action of promoting collapse of earth and sand and mixing with muddy water.

As the earth and sand passing through the crushing gap 6 pass through a narrow space, gravels and cobblestones are easily crushed. The muddy water containing earth and sand that has passed through the crushing gap 6 is conveyed to the ground via a drainage pipe 12. In particular, since the notch 8 is provided on the outer periphery of the inner cone 5, the notch 8 or the wide gap 7 is formed with the rotation of the inner cone 5.
Move sequentially along the inner circumference of. The viscous earth and sand which adheres to the cone guide 3 and the inner cone 5 in the crushing gap 6 and closes the crushing gap 6 is easily scraped off by the notch 8 or subjected to a shearing action, and thus easily detached. Gravel and boulders are notched 8
After entering the wide gap 7 with the inner cone 5
It is turned in the circumferential direction with the rotation of, and is crushed by being bitten by the peripheral edge of the notch 8. Since the wide gap 7 and the narrow gap 6 move alternately in the circumferential direction, the crushing gap 6
It is possible to prevent sediment from sticking and clogging over the entire circumference of the slab and efficiently crush gravels and boulders.

Further, since the muddy water is blown from the muddy water discharge port 36 to the crushing gap 6, the soil fixed on the inner cone 5 and the cone guide 3 in the crushing gap 6 is efficiently washed away. As a result, the adhesion and blockage of the earth and sand to the crushing gap 6 are favorably prevented. [Alternative Embodiment 1] The embodiment shown in FIG. 3 employs the same configuration as that of the above-described embodiment except that the supply structure of the cleaning liquid is different. Therefore, the different configuration will be mainly described.

A discharge port 24 of the cleaning liquid supply pipe 20 is opened at a location facing the crushing gap 6 on the inner periphery of the cone guide 3. The cleaning liquid supply pipe 20 is supplied with cleaning water from behind. In this embodiment, the supply of the washing water can be controlled separately from the supply of the muddy water for discharging the excavated earth and sand. Can supply water. [Alternative Embodiment 2] The embodiment shown in FIG. 4 employs the same configuration as that of the above-described embodiment except for the structure of the notch, so that the different configuration will be mainly described.

At the same position and shape as the notch 8 on the outer periphery of the inner cone 5, the notch 8 is also formed on the inner periphery of the cone guide 3.
Is provided. When the inner and outer notches 8 and 9 face each other with the rotation of the inner cone 5, the largest gap 7 'is formed. In the state where one notch 8 or 9 and the other flat peripheral surface face each other, a gap 7 of the same degree as in the above embodiment is formed, and when the inner and outer flat peripheral faces face each other, a narrow gap 6 is formed. Is configured.

Therefore, in the above-described embodiment, the change width of the crushing gap is large, and the above-described operation and effect associated with the change of the gap are more effectively exhibited. [Alternative Embodiment 3] The embodiment shown in FIG. 5 has the same configuration as that of the above-described embodiment except that the structure of the built-up portion arranged on the inner cone is different. Will be explained.

On the surface of the conical inner cone 5, a spiral build-up portion 13 formed by build-up welding is arranged. The direction of the helix matches the normal rotation direction of the inner cone 5. Specifically, when viewed from the front side of the cutter disk 4, the spiral build-up 13 shown in FIG. 5 rotates the inner cone 5 counterclockwise, and the spiral build-up 13 And extends rearward while turning in the direction opposite to the rotation direction of the motor.

When the inner cone 5 is rotated, the earth and sand that comes into contact with the spiral build-up portion 13 is sequentially sent rearward by the rotation of the spiral build-up portion 13 and is efficiently sent into the crushing gap 6. . In addition, gravel or the like comes into contact with or collides with the spiral build-up portion 13 and is crushed. [Embodiment 4] The embodiment shown in FIGS. 6 to 8 employs a configuration common to the above-described embodiment except that an inner cone and a cutter disk advance / retreat mechanism are provided. This will be explained.

As shown in FIG. 6, the advance / retreat mechanism 14 has a boss 15 fixed to a partition wall 19 of the excavator 1. Boss 1
A sliding body 16 fixed to a rear portion of the speed reducer 10 is slidably attached to the inside of the gear 5 using a spline mechanism. The inner cone 5 and the cutter disk 4 attached to the front of the speed reducer 10 and the drive unit 11 attached to the rear of the speed reducer 10 as a whole move back and forth inside the boss 15 together with the slide 16 together. .

Seal members 18, 18 are disposed between the inner surface of the boss 15 and the outer surface of the speed reducer 10 in front of the partition wall 19, and the sediment introduced into the space in front of the partition wall 19 is To prevent leakage behind. A jack 17 that expands and contracts in the front-rear direction is arranged on the back surface of the partition wall 19. The tip of the jack 17 is pivotally attached to an arm 10a extending from the rear end of the speed reducer 10 to the outer periphery.

When the jack 17 is extended and retracted back and forth, the arm 1
The speed reducer 10, the inner cone 5, the cutter disk 4, the drive unit 11, and the sliding body 16 advance and retreat through the Oa. FIG. 7 shows a state where the jack 17 is extended and the inner cone 5 and the cutter disk 4 are retracted. Inner cone 5 than the rear end of guide cone 3
The rear end is located rearward. The crushing gap 6 is slightly wider than in a state where the guide cone 3 and the rear end of the inner cone 5 are at substantially the same position (FIG. 6).

FIG. 8 shows a state in which the jack 17 is contracted and the inner cone 5 and the cutter disk 4 are advanced. The rear end of the inner cone 5 is located forward of the rear end of the guide cone 3, and the crushing gap 6 is considerably wide. When the state of FIG. 7 is compared with the state of FIG. 8, in the state of FIG. 8, the crushing gap 6 is wider and the flow of earth and sand when passing through the crushing gap 6 is different.

In the above embodiment, by moving the position of the inner cone 5 back and forth, a structural arrangement suitable for changes in soil properties and construction conditions can be achieved. For example, when the ground changes from a gravel or boulder layer to a clay layer, the blockage due to the compaction of the earth and sand in the crushing gap 6 is released by moving the inner cone 5 to the position shown in FIG. can do. When the ground returns to the gravel layer,
If the inner cone 5 is returned to the normal position shown in FIG. 6, a crushing gap 6 suitable for crushing gravels and cobblestones can be provided.

[0041]

The shield machine according to the present invention is provided with the notch, so that the earth and the like adhere to the crushing gap between the cone guide and the inner cone, or the gap is formed by the compacted earth and sand. Blockage can be prevented. The crushing action on gravel and the like can be performed well. As a result, an efficient propulsion method can be realized even under ground conditions, such as an alternate layer of a gravel layer and a clay layer, which is difficult to propel with a conventional excavator for a gravel layer.

If the size of the notch is set within the above specific range, the above-mentioned effect of the notch can be exhibited well. If the outer peripheral surface of the inner cone is provided with a spiral build-up, earth and sand can be efficiently sent to the rear crushing gap along the outer peripheral surface of the inner cone, and crushing of gravel and the like can be performed efficiently.

If an inner cone advance / retreat mechanism is provided, the position of the inner cone and the arrangement of crushing gaps can be set according to the soil conditions, and complicated soil properties such as alternating layers of gravel and clay layers can be set. Efficient excavation becomes possible even on the ground having a structure. If the cleaning liquid supply means is provided, even if clayey earth and sand or the like adheres to or closes the crushing gap, the soil and sand can be washed out and the function of the crushing gap can be restored.

If muddy water for mud sending is used as washing water,
There is no need to add a new mechanism for supplying the cleaning water. Therefore, it is easy to additionally construct a cleaning water supply mechanism for the existing excavator.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is an axial sectional view of an excavator.

FIG. 2 is a front view showing the structure of a cone guide and an inner cone.

FIG. 3 is an axial cross-sectional view of an excavator showing another embodiment.

FIG. 4 is a front view of a cone guide and an inner cone representing another embodiment.

FIG. 5 is a sectional view showing a structure of a tip portion of an excavator showing another embodiment.

FIG. 6 is a schematic structural diagram of an excavator showing another embodiment.

FIG. 7 is a schematic structural diagram showing a first operating state.

FIG. 8 is a schematic structural diagram showing a second operation state.

FIG. 9 is a front view of a cone guide and an inner cone representing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Excavator 2 Outer shell 3 Cone guide 4 Cutter disk 5 Inner cone 6,7 Crush gap 8,9 Notch 10 Reducer 11 Driver 12 Drainage pipe 13 Build-up part 14 Retreat mechanism 15 Boss 20 Cleaning liquid supply pipe 24 36 Cleaning liquid discharge port 31 Mud pipe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-U 5-96195 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) E21D 9/08 E21D 9/06 311

Claims (5)

(57) [Claims] 1. A shield excavator for a propulsion method for excavating a ground by using an excavator, propelling a buried pipe connected to a rear of the excavator together with the excavator, and burying the buried pipe. A cutter disk that is rotatably arranged on the front of the machine and excavates the ground, is disposed behind the cutter disk inside the excavator, and has a conical shape in which the inside diameter decreases toward the rear,
A cone guide into which the earth and sand excavated by the cutter disc are fed into the inner space; and a cone shaped rotatably disposed behind the cutter disc inside the cone guide, the outer diameter of which increases toward the rear. Forming a narrow crushing gap between the cone guide at the rear end, an inner cone for crushing the earth and sand at the crushing gap, and an inner circumference of the cone guide facing the crushing gap and an outer circumference of the inner cone. A shield excavator comprising: a notch in which a plurality of notches are arranged at least one of them at intervals in a circumferential direction. 2. The notch has a width of 40 to 60 mm and a depth of 40 mm.
The shield machine according to claim 1, which has a length of about 60 mm. 3. A shield excavator for a propulsion method in which an excavator excavates the ground while propelling a buried pipe connected to the back of the excavator together with the excavator to bury the buried pipe. A cutter disk that is rotatably arranged on the front of the machine and excavates the ground, is disposed behind the cutter disk inside the excavator, and has a conical shape in which the inside diameter decreases toward the rear,
A cone guide into which the earth and sand excavated by the cutter disc are fed into the inner space; and a cone shaped rotatably disposed behind the cutter disc inside the cone guide, the outer diameter of which increases toward the rear. A shield excavator comprising a narrow crushing gap between the cone guide at the rear end and an inner cone for crushing the earth and sand in the crushing gap, and an advancing / retracting mechanism for moving the inner cone back and forth. Wherein said opening in the inner periphery of the cone guide facing the crushing gap, shield machine according to any one of claims 1 to 3, further comprising a cleaning liquid supply means for supplying a cleaning liquid into the crushing gap. 5. The excavator further comprises a mud feed pipe which is opened on an inner peripheral surface of the cone guide and supplies muddy water to a back surface of the cutter disk, and wherein the washing liquid supply means removes a part of the muddy water. The shield machine according to claim 4, which is used as a cleaning liquid.