Bentonite slurry wall protection device suitable for complex stratum

Abstract

The utility model relates to the technical field of building foundation construction, and discloses a bentonite slurry wall protection device suitable for complex stratums, which comprises a drill bit and a troweling plate, a first column body is fixed above the troweling plate, a top cover provided with a slurry inlet pipe is arranged at the top of the first column body, an air cylinder connected with the first column body is arranged below the top cover, and a telescopic shaft extends out of the air cylinder. The baffle disc is arranged in the first column body and provided with a through hole communicated with the slurry flowing pipe, the two trowelling mechanisms are fixed to the telescopic shaft, each trowelling mechanism comprises a cross rod, a connecting rod and other components, a trowelling plate makes contact with the hole wall through cooperation of a push rod, a pressing rod and a rotating shaft, and slurry outlets communicated with the slurry flowing pipe are formed in the periphery of a drill bit. After bentonite slurry is sprayed out of the slurry outlet, the trowelling plate can flatten and compact the wall face, protrusions or uneven positions on the hole wall are trimmed to be smooth, under the trowelling effect of the trowelling plate, a layer of compact, even and continuous mud cake can be formed on the wall face, and the wall protection effect is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to building foundation construction technical field, especially in complex stratum's bentonite mud slurry wall device. BACKGROUND

[0002] In the construction engineering, especially when carrying out pile foundation construction, in order to prevent the hole wall collapse in the drilling process, ensure construction safety and quality, mud slurry wall technology is widely used, and mud slurry wall drilling device plays a key role in drilling operation, it can form mud skin on the hole wall, prevent the hole wall collapse of loose and easy to collapse stratum, stabilize the drilling space, when operating, the mud slurry in the device can carry drilling cuttings from the hole bottom to the outside of the hole, avoid the influence of drilling cuttings accumulation on drilling, at the same time, the mud slurry can cool and lubricate the drill bit, reduce its wear and tear, prolong the service life, in the stratum with underground water, it can also balance water pressure, prevent underground water from gushing, guarantee construction safety and drilling quality.

[0003] The utility model discloses a device for forming soft soil foundation rotary drilling pile mud slurry wall, can spray concrete from the spray head fixed on the connecting ring while opening the hole, but the mud slurry wall drilling device still has the following defects when working: the mud slurry flowing out of the spray head adheres to the hole wall by itself flowing and permeating, it is difficult to ensure that the mud slurry uniformly covers the hole wall, and the mud slurry forms mud skin on the hole wall relatively naturally and randomly after flowing out of the spray head, and a tight, uniform and continuous mud skin cannot be formed. UTILITY MODEL CONTENTS

[0004] The utility model discloses a bentonite mud slurry wall device suitable for complex stratum, after the bentonite mud slurry is sprayed out of the slurry outlet, the trowelling plate can carry out the flattening and compaction operation to the wall surface, the protrusions or uneven places on the hole wall are smoothed, and under the trowelling effect of the trowelling plate, the wall surface can form a layer of tight, uniform and continuous mud skin, and the wall protection effect is improved.

[0005] The utility model discloses a bentonite mud slurry wall device suitable for complex stratum, which comprises a conical drill bit, a first column body vertically arranged at the top end of the drill bit and a trowelling plate movably arranged on one side of the first column body in the vertical direction, the diameter of the first column body is smaller than that of the top end of the drill bit, a top cover is horizontally arranged at the top of the first column body, an inlet pipe is arranged on the top cover, a flow pipe is arranged in the first column body and communicates with the inlet pipe, an outlet is formed in the drill bit and communicates with the bottom end of the flow pipe, and a trowelling mechanism is arranged in the first column body and used for driving the trowelling plate to extend and retract for trowelling.

[0006] Through adoption of the above technical scheme, the mud can enter the inside of the device through the mud inlet pipe, and then flow to the surroundings of the drill bit through the flow mud pipe and the mud outlet communicated with the flow mud pipe, so that the mud reaches the hole wall in time during the drilling process.

[0007] The further setting of the utility model is that: the trowelling mechanism includes a cylinder vertically arranged in the first column body and a telescopic shaft arranged at the output end of the cylinder, a plurality of horizontal rods are sequentially arranged on the telescopic shaft in the axial direction, vertical rods are vertically arranged at the two ends of the horizontal rods, a pressing rod is horizontally arranged at the middle part of the vertical rod, an L-shaped push rod is horizontally arranged at the bottom end of the vertical rod, the push rod is located directly below the adjacent pressing rod, a plurality of rotating shafts matched with the push rods are arranged on the inner wall of the first column body in the horizontal direction, a connecting rod is rotatably arranged on the rotating shaft, a telescopic opening is arranged on the side of the first column body close to the connecting rod, the connecting rod is movably arranged through the telescopic opening, a plurality of connecting seats corresponding to the connecting rods are arranged on one side of the trowelling plate, the end part of the connecting rod is hinged with the adjacent connecting seat, when the telescopic shaft descends, the pressing rod can push the connecting rod to rotate downward to the horizontal direction, when the telescopic shaft ascends, the push rod can push the connecting rod to rotate upward.

[0008] Through adoption of the above technical scheme, when the cylinder drives the telescopic shaft to descend, the pressing rod on the horizontal rod moves downward along with the telescopic shaft, since the pressing rod is located above the connecting rod, the pressing rod pushes the connecting rod to rotate downward around the rotating shaft, when the connecting rod rotates to the horizontal direction, the connecting seat hinged with the end part of the connecting rod drives the trowelling plate to stretch out in the direction away from the first column body, so that the trowelling plate can trowel the mud on the hole wall, and the uniformity and flatness of the mud protection layer are ensured.

[0009] When the drilling work is completed, the cylinder drives the telescopic shaft to ascend, the push rod on the horizontal rod moves upward along with the telescopic shaft, since the push rod is located below the connecting rod, the push rod pushes the connecting rod to rotate upward around the rotating shaft, so that the connecting seat hinged with the end part of the connecting rod drives the trowelling plate to shrink in the direction close to the first column body, in this way, the trowelling plate shrinks to the appropriate position, the drilling device is conveniently lifted out of the hole, the collision or scraping between the trowelling plate and the hole wall in the lifting process is avoided, and the smooth operation and safe use of the device are ensured.

[0010] The further setting of the utility model is that: the cross section of the first column body is rectangular, a cylindrical second column body is arranged outside the first column body, an adaptive groove is arranged on the side of the second column body close to the trowelling plate.

[0011] By adopting the technical scheme, the first column body is in a rectangular cross section, facilitating reasonable arrangement of components of the smearing mechanism such as the cylinder and the telescopic shaft inside the first column body, and a cylindrical second column body is arranged outside the first column body, and an adaptive slot is arranged on one side of the second column body close to the smearing plate, on the one hand, the cylindrical second column body can provide more stable external structural support for the whole device, enhancing the overall strength and stability of the device during drilling in complex strata.

[0012] On the other hand, the adaptive slot can provide a suitable storage space for the smearing plate when the smearing plate is retracted, so that the smearing plate can better fit the device after retraction, further avoiding collision or scratching of the smearing plate with the hole wall when the drilling device is lifted, and also protecting the smearing plate to some extent, prolonging the service life of the smearing plate.

[0013] In addition, the presence of the second column body can also protect the mud flow channel and other structures inside the first column body to some extent, preventing mud overflow or external debris from entering, ensuring normal mud wall protection work, thereby improving the construction quality and efficiency of mud wall protection.

[0014] The utility model further provides that the diameter of the top cover is equal to the diameter of the second column body.

[0015] By adopting the above technical scheme, the equal diameter enables the top cover to better cooperate with the second column body, if the diameter of the top cover is too small, the broken earth generated by drilling is easy to fall into the first column body, interfering with the normal operation of the equipment, and if the diameter of the top cover is too large, it will form an obstacle in the drilling process, only when the diameter of the top cover is moderate, can the drilling operation be carried out smoothly, and unnecessary waste of top cover preparation materials can be avoided.

[0016] The utility model further provides that the number of the cross bars and the rotating shafts is 2, two pressing rods and push rods are symmetrically arranged on the vertical rods, and connecting rods matched with the adjacent pressing rods are symmetrically and rotatably arranged on the rotating shafts.

[0017] By adopting the above technical scheme, when the cylinder drives the telescopic shaft to descend, the pressing rods on the two cross bars can simultaneously and symmetrically exert downward thrust on the connecting rods, so that the connecting rods are stably rotated to the horizontal direction around the rotating shafts, and then the smearing plate is extended away from the first column body, in this process, due to the symmetrical application of force, the driving force received by each part of the smearing plate is balanced, the smearing plate can more stably and evenly contact and smoothen the mud on the hole wall, avoiding inclination or shaking of the smearing plate due to uneven force, thereby ensuring the uniformity and flatness of the mud wall layer.

[0018] When the drilling work is completed, the cylinder drives the telescopic shaft to rise, and the push rods on the two cross rods symmetrically apply upward thrust to the connecting rod, so that the connecting rod rotates upward around the rotating shaft, and drives the smoothing plate to shrink in the direction close to the first column body, and the symmetrical structure design makes the shrinking process more stable and smooth, and the smoothing plate can be accurately shrunk to the appropriate position.

[0019] The utility model discloses further provide that: the cross section of smoothing plate is arc, and the diameter of smoothing plate is equal to the diameter of the top of drill bit.

[0020] By adopting the above technical scheme, the shape of the arc-shaped plate is more matched with the shape of the hole wall after drilling, and the outer diameter is consistent with the diameter of the top of the drill bit, so that the arc-shaped plate can closely contact the hole wall and uniformly smooth the bentonite mud on the hole wall without gap when the smoothing mechanism drives the arc-shaped plate to work, compared with other shapes of smoothing plates, the unevenness and uneven thickness of the hole wall mud can be effectively reduced, the flatness and quality of the wall protection layer are greatly improved, the wall protection effect is enhanced, and the risk of hole wall collapse is reduced.

[0021] The utility model discloses further provide that: the inner wall of first column body is horizontally provided with a baffle disc, and the cylinder is fixedly arranged at the top of the baffle disc, and the telescopic shaft is located below the baffle disc, and the slurry inlet pipe passes through the baffle disc.

[0022] By adopting the above technical scheme, on the one hand, the baffle disc can constrain the movement track of the telescopic shaft to a certain extent, so that the telescopic shaft can only move up and down along the vertical direction, avoiding lateral deviation or shaking of the telescopic shaft during movement, improving the stability and accuracy of the movement of the telescopic shaft, and further ensuring the accuracy and reliability of the telescopic action of the smoothing plate, and on the other hand, the baffle disc can prevent the slurry inlet pipe from shaking or shifting during the working process of the device, so that the mud can stably flow into the inside of the device through the slurry inlet pipe.

[0023] The utility model discloses further provide that: the baffle disc is provided with a rubber sealing ring outside the circumference.

[0024] By adopting the above technical scheme, the rubber sealing ring has good elasticity and sealing property, can closely contact the gap between the baffle disc and the first column body, and can effectively prevent the mud from leaking from the joint of the baffle disc and the first column body during the flow of the mud from the slurry inlet pipe, so as to ensure that the mud flows along the predetermined path.

[0025] The utility model discloses further provide that: the material of slurry inlet pipe is stainless steel.

[0026] By adopting the technical scheme, in complex strata, the mud composition is complex, and may contain various acid and alkali substances, salt, and corrosive mineral ions, etc., the stainless steel has good corrosion resistance, can effectively resist the corrosion of these corrosive media, ensures that the flow pipe does not appear problems such as thinning of the pipe wall and perforation due to corrosion in the long-term use process, guarantees the safety and stability of mud conveying, prolongs the service life of the flow pipe, and reduces the equipment downtime and maintenance cost caused by pipeline corrosion damage.

[0027] The utility model discloses the beneficial effect is:

[0028] 1. The mud can enter the device inside through the inlet pipe, then flow to the drill bit through the flow pipe and the outlet port communicated with the flow pipe, so that the mud reaches the hole wall in time during the drilling process, and the trowel plate is driven by the troweling mechanism to trowel the mud on the hole wall, so that the wall protection layer is more uniform and flat, and the wall protection effect is improved.

[0029] 2. When the cylinder drives the telescopic shaft to descend, the pressure rod on the cross bar moves downward along with the telescopic shaft, and since the pressure rod is above the connecting rod, the pressure rod pushes the connecting rod to rotate downward around the rotating shaft, and when the connecting rod rotates to the horizontal direction, the connecting seat hinged to the end of the connecting rod drives the trowel plate to extend away from the first column, so that the trowel plate can trowel the mud on the hole wall, and the uniformity and flatness of the mud wall protection layer are ensured.

[0030] 3. When the drilling work is completed, the cylinder drives the telescopic shaft to ascend, and the push rod on the cross bar moves upward along with the telescopic shaft, and since the push rod is below the connecting rod, the push rod pushes the connecting rod to rotate upward around the rotating shaft, so that the connecting seat hinged to the end of the connecting rod drives the trowel plate to shrink towards the first column, so that the trowel plate shrinks to the appropriate position, the drilling device can be lifted out of the hole, and collision or scratching between the trowel plate and the hole wall during the lifting process is avoided, so that the smooth operation and safe use of the device are ensured.

[0031] 5. The trowel plate is an arc-shaped plate, the shape of the arc-shaped plate is more suitable for the shape of the hole wall after drilling, and the outer diameter is consistent with the diameter of the top end of the drill bit, so that the trowel plate can closely fit the hole wall and uniformly trowel the bentonite mud on the hole wall without gaps when the trowel mechanism drives the trowel plate to work, and the flatness and quality of the wall protection layer are greatly improved.

[0032] 6. The outer circumference of the baffle disc is sleeved with a rubber sealing ring, the rubber sealing ring has good elasticity and sealing performance, can closely fit the gap between the baffle disc and the first column, and can effectively prevent the mud from leaking from the joint between the baffle disc and the first column.

[0033] 7. The material of the pulp flow pipe is stainless steel, which has good corrosion resistance, can effectively resist the corrosion of corrosive medium in the slurry, prolong the service life of the pulp flow pipe and reduce the maintenance cost. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0035] Figure 1 is a schematic view of the overall structure of the present application.

[0036] Figure 2 is a schematic view of the overall structure of the present application.

[0037] Figure 3 is a side view of the internal structure of the present application.

[0038] Figure 4 is an axonometric view of the internal structure of the present application.

[0039] Figure 5 is a sectional view of the overall structure of the present application.

[0040] In the figure, 1 is a pulp inlet pipe, 2 is a cylinder, 3 is a trowel plate, 4 is a connecting rod, 5 is a pressing rod, 6 is a rotating shaft, 7 is a vertical rod, 8 is a push rod, 9 is a baffle disc, 10 is a connecting seat, 11 is an extension shaft, 12 is a cross rod, 13 is a top cover, 14 is a second column, 15 is a first column, 16 is a drill bit, 17 is a pulp outlet, 18 is a pulp flow pipe, 19 is an extension port, and 20 is an adaptive groove. DETAILED DESCRIPTION

[0041] The technical solutions of the present application will be described clearly and completely in combination with specific embodiments. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application. The device is arranged at the output end of the existing mining equipment in actual work.

[0042] Figures 1 to 5As shown, the utility model provides a bentonite mud wall protection device suitable for complex stratum, including conical drill bit 16, vertical setting first cylinder 15 of the top of drill bit 16 and the side of first cylinder 15 along vertical direction movable setting trowelling plate 3, the diameter of first cylinder 15 is less than the diameter of the top of drill bit 16, and the top of first cylinder 15 is provided with top cover 13, and top cover 13 is equipped with inlet tube 1, and the inside of first cylinder 15 is provided with flow tube 18 that communicates with inlet tube 1, and drill bit 16 is provided with outlet 17 that communicates with the bottom of flow tube 18, and the inside of first cylinder 15 is provided with trowelling mechanism for driving trowelling plate 3 to stretch and retract and trowelling.

[0043] Further, trowelling mechanism includes vertical setting air cylinder 2 in first cylinder 15 and stretchable shaft 11 setting on the output end of air cylinder 2, and a plurality of cross bars 12 are sequentially arranged on stretchable shaft 11 along the axial direction, and vertical bars 7 are vertically arranged on both ends of cross bar 12, and pressure bars 5 are horizontally arranged on the middle part of vertical bar 7, and L-shaped push rods 8 are horizontally arranged on the bottom end of vertical bar 7, and push rod 8 is located directly below adjacent pressure bar 5, and a plurality of rotating shafts 6 matched with push rod 8 are horizontally arranged on the inner wall of first cylinder 15, and connecting rods 4 are rotatably arranged on rotating shaft 6, and stretchable opening 19 is arranged on the side of first cylinder 15 close to connecting rod 4, and connecting rod 4 movably passes through stretchable opening 19, and a plurality of connecting seats 10 corresponding to connecting rod 4 are arranged on one side of trowelling plate 3, and the end of connecting rod 4 is hingedly connected with adjacent connecting seat 10, and when stretchable shaft 11 descends, pressure bar 5 can push connecting rod 4 to rotate downward to the horizontal direction, and when stretchable shaft 11 rises, push rod 8 can push connecting rod 4 to rotate upward.

[0044] Further, the cross section of first cylinder 15 is rectangular, and a cylindrical second cylinder 14 is arranged on the outer side of first cylinder 15, and an adaptive groove 20 is arranged on the side of second cylinder 14 close to trowelling plate 3.

[0045] Further, the diameter of top cover 13 is equal to the diameter of second cylinder 14.

[0046] Further, the number of cross bars 12 and rotating shafts 6 is both 2, and two pressure bars 5 and push rods 8 are symmetrically arranged on vertical bar 7, and connecting rods 4 matched with adjacent pressure bars 5 are rotatably arranged on rotating shaft 6.

[0047] Further, the cross section of trowelling plate 3 is circular arc, and the diameter of trowelling plate 3 is equal to the diameter of the top of drill bit 16.

[0048] Further, a baffle 9 is horizontally arranged on the inner wall of first cylinder 15, air cylinder 2 is fixedly arranged on the top end of baffle 9, stretchable shaft 11 is located below baffle 9, and inlet tube 1 movably passes through baffle 9.

[0049] Further, a rubber sealing ring is sleeved on the outer circumference of baffle 9.

[0050] Further, the material of the flow tube 18 is stainless steel.

[0051] The utility model discloses, when the cylinder 2 drives telescopic shaft 11 to descend, the pressure bar 5 on cross bar 12 will move down with telescopic shaft 11, because the pressure bar 5 is located above connecting rod 4, the pressure bar 5 will push connecting rod 4 and rotate down around pivot 6, when connecting rod 4 rotates to horizontal direction, with the connecting seat 10 of the articulated end of connecting rod 4, will drive the trowelling plate 3 and stretch out to the direction of away from the first cylinder 15, to make the trowelling plate 3 can the mud on the hole wall is trowelled and is operated, guarantees the uniformity and the even of mud protection wall layer, when the drilling work is completed, the cylinder 2 drives telescopic shaft 11 to rise, the push rod 8 on cross bar 12 will move up with telescopic shaft 11, because the push rod 8 is located below connecting rod 4, the push rod 8 will push connecting rod 4 and rotate up around pivot 6, make with the connecting seat 10 of the articulated end of connecting rod 4 drive trowelling plate 3 and shrink to the direction of close to the first cylinder 15, in this way, trowelling plate 3 contracts to the appropriate position, the drilling device is lifted from the drilling, avoid the collision or scraping of trowelling plate 3 with hole wall in the lifting process, guarantee the smooth operation and safe use of device.

[0052] As Figure 5 The utility model discloses a working process is:

[0053] S1: grouting: the grout pipe 1 is connected with the spiral of sending slurry pipe, and the mud enters the drilling device and flows to the hole wall around the drill bit 16 through the flow tube 18 and the slurry outlet 17.

[0054] S2: trowelling: during the drilling process, the gear position of the cylinder 2 is adjusted to the telescopic shaft 11 elongation, in the telescopic shaft 11 elongation process, the vertical position of the pressure bar 5 also changes, in this process, the pressure bar 5 will gradually press connecting rod 4 to the horizontal direction, and connecting rod 4 drives trowelling plate 3 and contacts the hole wall and pushes the hole wall, so that the mud on the hole wall is trowelled and handled.

[0055] S3: shrinkage: when the operation is completed, the gear position of the cylinder 2 is adjusted to the telescopic shaft 11 contraction, in the telescopic shaft 11 contraction process, the vertical position of the push rod 8 also changes, in this process, the push rod 8 will push connecting rod 4 to gradually tilt, and trowelling plate 3 will shrink to the first cylinder 15 of drilling, to facilitate the lifting of the drilling device.

Claims

1. A bentonite mud shoring device suitable for use in complex ground formations, characterized in that: The utility model provides a kind of drilling head (16) including conical, first cylinder (15) vertically arranged in the top end of the drilling head (16) and trowelling plate (3) vertically movably arranged in the side of the first cylinder (15), the diameter of the first cylinder (15) is less than the diameter of the top end of the drilling head (16), top cover (13) is horizontally arranged in the top of the first cylinder (15), the top cover (13) is equipped with slurry inlet pipe (1), the inside of the first cylinder (15) is equipped with with slurry inlet pipe (1) communication flow slurry pipe (18), the drilling head (16) is equipped with with slurry outlet (17) of the bottom end of flow slurry pipe (18) communication on it, the inside of the first cylinder (15) is equipped with for driving the trowelling plate (3) telescopic and trowelling trowelling mechanism.

2. A bentonite slurry wall device suitable for use in complex ground formations according to claim 1, characterised in that: The trowelling mechanism includes cylinder (2) vertically arranged in the first cylinder (15) and telescopic shaft (11) arranged at the output end of the cylinder (2), a plurality of cross bars (12) are sequentially arranged on the telescopic shaft (11) in the axial direction, vertical rods (7) are vertically arranged at both ends of the cross bar (12), pressure rods (5) are horizontally arranged at the middle part of the vertical rod (7), L-shaped push rods (8) are horizontally arranged at the bottom end of the vertical rod (7), the push rod (8) is located below the adjacent pressure rod (5), a plurality of rotating shafts (6) are arranged on the inner wall of the first cylinder (15) in the horizontal direction, the rotating shaft (6) is rotatably arranged with a connecting rod (4), a telescopic opening (19) is formed on the side of the first cylinder (15) close to the connecting rod (4), the connecting rod (4) passes through the telescopic opening (19) movably, a plurality of connecting seats (10) are arranged on one side of the trowelling plate (3) corresponding to the connecting rod (4), the end of the connecting rod (4) is hinged to the adjacent connecting seat (10), when the telescopic shaft (11) descends, the pressure rod (5) can push the connecting rod (4) to rotate downward to the horizontal direction, when the telescopic shaft (11) rises, the push rod (8) can push the connecting rod (4) to rotate upward.

3. A bentonite slurry wall device suitable for use in complex ground formations according to claim 2, wherein: The cross section of the first cylinder (15) is rectangular, and a cylindrical second cylinder (14) is arranged on the outer side of the first cylinder (15).

4. A bentonite slurry wall device suitable for use in complex ground formations according to claim 3, wherein: The diameter of the top cover (13) is equal to the diameter of the second cylinder (14).

5. A bentonite slurry wall device suitable for use in complex ground formations according to claim 2, wherein: The number of the cross bar (12) and the rotating shaft (6) is 2, and two pressure rods (5) and push rods (8) are symmetrically arranged on the vertical rod (7), and the connecting rod (4) is symmetrically rotatably arranged on the rotating shaft (6) corresponding to the adjacent pressure rod (5).

6. A bentonite slurry wall device suitable for use in complex ground formations according to claim 1, wherein: The cross section of the trowelling plate (3) is circular arc, and the diameter of the trowelling plate (3) is equal to the diameter of the top end of the drilling head (16).

7. A bentonite slurry wall device suitable for use in complex ground formations according to claim 2, wherein: The inner wall of the first column (15) is horizontally provided with a baffle disc (9), the cylinder (2) is fixedly arranged at the top end of the baffle disc (9), the telescopic shaft (11) is located below the baffle disc (9), and the pulp feeding pipe (1) penetrates through the baffle disc (9) movably.

8. A bentonite slurry wall device suitable for use in complex ground formations according to claim 7, wherein: A rubber sealing ring is sleeved at the outer circumference of the baffle disc (9).

9. A bentonite slurry wall device suitable for use in complex ground formations according to claim 1, wherein: The material of the pulp feeding pipe (18) is stainless steel.

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