JP7247126B2 - screw press - Google Patents

Description

The present invention relates to a screw press for squeezing liquid containing material such as sludge to separate liquid from the liquid containing material.

Conventionally, a screw press has been used as a device for squeezing sludge (liquid containing matter) discharged from liquid treatment facilities such as water and sewage treatment plants and night soil treatment plants to separate water from the sludge (that is, dewatering). Are known.

This screw press includes a filter cylinder formed of a screen (perforated plate) and a screw arranged inside the filter cylinder. The screw squeezes and dehydrates the sludge introduced into the filter cylinder. Dehydrated sludge (cake) is discharged from the discharge side end of the filter tube.

JP 2010-253536 A JP 2018-51582 A

However, pressed sludge may enter the internal space of the screw. Sludge that has entered this internal space may adversely affect the operation of the screw press. Alternatively, it takes a lot of time and effort to discharge the sludge present in the internal space.

Accordingly, an object of the present invention is to provide a screw press that reliably prevents sludge from entering the internal space of the screw.

In one aspect, a filter cylinder into which the liquid-containing material is introduced, and a first screw and a second screw arranged concentrically with the filter cylinder in the filter cylinder and transporting the liquid-containing material in a predetermined transport direction. and a bearing disposed between the first screw and the second screw, wherein the second screw has a second screw shaft having a recess into which the first screw shaft of the first screw is inserted. Between the filter cylinder and the first screw shaft and the second screw shaft, a compression flow path for compressing the liquid containing material is formed, and the bearing is provided with the A screw press is provided that has a through channel that communicates a closed space formed between a first screw shaft and a second screw shaft with the compression channel.

In one aspect, the through channel is a groove formed on the surface of the bearing.
In one aspect, the through channel is a through hole formed in the bearing.

In one aspect, the second screw includes a drainage hole formed in the second screw shaft, and a drainage plug closing the drainage hole.
In one aspect, the second screw includes a lubricating fluid injection hole formed in the second screw shaft, and an injection plug closing the lubricating fluid injection hole.
In one aspect, the screw press includes a pressure sensing device that senses the internal pressure of the closed space.

The bearing communicates the closed space and the squeeze channel with each other through the through channel. Therefore, the pressure in the closed space becomes the same as the pressure in the compression channel, which is increased by squeezing the sludge. As a result, no pressure difference occurs between the compression channel and the enclosed space, and sludge does not enter the enclosed space.

It is a schematic diagram showing a screw press according to one embodiment. FIG. 2 is a schematic cross-sectional view of a second screw shown in FIG. 1; It is a schematic sectional drawing which shows other embodiment of a 2nd screw. It is an enlarged view of a bearing. 1 is a perspective view of a bearing; FIG. FIG. 10 is a diagram showing another embodiment of a through channel; FIG. 10 is a view showing a lubricating fluid injection hole formed in the reduced diameter portion of the second screw shaft and an injection plug closing the lubricating fluid injection hole; It is a figure which shows the pressure detection apparatus which detects the internal pressure of a sealed space.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing a screw press according to one embodiment. The screw press shown in FIG. 1 includes a cylindrical screen casing (filtration cylinder) 1, which is arranged concentrically with the screen casing 1 in the screen casing 1, and sludge (liquid content) is transferred in a predetermined transfer direction D. A first screw 3 and a second screw 4 to be transferred, a first rotating mechanism 7 for rotating the first screw 3, and a second rotating mechanism 20 for rotating the second screw 4 independently of the first screw 3. I have it.

The screen casing 1 is formed of a screen (perforated plate) such as punching metal. A sludge inlet 2 is formed at the upstream end of the screen casing 1 . Sludge introduced into the screen casing 1 from the inlet 2 is transferred in a predetermined transfer direction D within the screen casing 1 by the rotating first screw 3 and second screw 4 . Furthermore, the screw press has a control section 6 that controls the operations of the first rotating mechanism 7 and the second rotating mechanism 20 .

The second screw 4 is connected to the first screw 3 so as to be rotatable independently of the first screw 3 . The first screw 3 and the second screw 4 extend through the screen casing 1 and the discharge chamber 33 respectively. A discharge chamber 33 is connected to the screen casing 1 . A plug cake, which will be described later, is discharged from the screen casing 1 into the discharge chamber 33 . The axial length of the second screw 4 is shorter than the axial length of the first screw.

The first screw 3 has a truncated cone-shaped (tapered) first screw shaft 3A whose diameter gradually increases toward the downstream side in the sludge transfer direction D, and is fixed to the outer surface of the first screw shaft 3A. and a first screw blade 3B. The second screw 4 has a cylindrical second screw shaft 4A and second screw blades 4B fixed to the outer surface of the second screw shaft 4A. The second screw 4 is arranged downstream of the first screw 3 in the transport direction D of the sludge.

The upstream end of the screen casing 1 is sealed by a closing wall 8 . One end (the upstream end in the transfer direction D) of the first screw shaft 3A extends through the closing wall 8 . A water sealing device 10 is installed on the closing wall 8 to seal the gap between the closing wall 8 and the first screw shaft 3A. The upstream end of the first screw shaft 3A extending through the closing wall 8 is rotatably supported by bearings 11 and 12 installed on a base (not shown) while restraining axial movement. . One of the bearings 11 and 12 can be omitted.

The upstream end of the first screw shaft 3A is connected to a first rotating mechanism 7 for rotating the first screw 3. As shown in FIG. In this embodiment, the first rotating mechanism 7 includes a first driving machine (for example, an electric motor) 14, a sprocket 15 fixed to the rotating shaft of the first driving machine 14, and a sprocket fixed to the first screw shaft 3A. 16 and a chain 17 wound around these sprockets 15 and 16. - 特許庁

A sprocket 16 is positioned between the bearings 11 and 12 . When the first driving machine 14 of the first rotating mechanism 7 is driven, the sprocket 15 fixed to the rotating shaft of the first driving machine 14 rotates, and the sprocket 16 fixed to the first screw shaft 3A via the chain 17 rotates. to rotate. As a result, the first screw 3 is rotated by the first rotating mechanism 7 . The first driving machine 14 is connected to the control section 6 , and the control section 6 is configured to be able to control the operation of the first driving machine 14 .

Although not shown, the rotating shaft of the first driving device 14 may be connected to the first screw shaft 3A via a speed reducer. Alternatively, the rotating shaft of the first driving machine 14 may be directly connected to the first screw shaft 3A.

FIG. 2 is a schematic cross-sectional view of the second screw 4 shown in FIG. As shown in FIG. 2, the second screw shaft 4A has a hollow structure. A diameter-reduced portion 3C is formed at the other end of the first screw shaft 3A (downstream end in the transfer direction D) to be inserted into the cylindrical second screw shaft 4A.

By forming the reduced-diameter portion 3C on the first screw shaft 3A, a wall surface 3D perpendicular to the axial direction is formed on the first screw shaft 3A. The reduced diameter portion 3C is inserted into the cylindrical second screw shaft 4A and rotatably supported by slide bearings 30 and 31 fixed to the inner wall 4C of the second screw shaft 4A. With such a configuration, the first screw 3 is rotatably connected with the second screw 4 .

As shown in FIGS. 1 and 2, the second screw shaft 4A of the second screw 4 is arranged concentrically with the first screw shaft 3A. The outer diameter of the second screw shaft 4A is the same as the maximum diameter of the first screw shaft 3A. A reduced diameter portion 4F extending through the inner wall 33A of the discharge chamber 33 is formed on the second screw shaft 4A. By forming the reduced diameter portion 4F on the second screw shaft 4A, a wall surface 4D perpendicular to the axial direction is formed on the second screw shaft 4A.

The upstream end of the second screw shaft 4A is rotatably supported by the first screw shaft 3A via the sliding bearings 30 and 31, and the downstream end of the second screw shaft 4A is connected to a base (not shown). ) are rotatably supported while restrained from moving in the axial direction by bearings 22 and 23 installed in the body. Note that the bearing 23 can be omitted.

A downstream end of the second screw shaft 4A is connected to a second rotating mechanism 20 for rotating the second screw 4 . In this embodiment, the second rotating mechanism 20 includes a second driving machine (for example, an electric motor) 24, a sprocket 25 fixed to the rotating shaft of the second driving machine 24, and a sprocket fixed to the second screw shaft 4A. 26 and a chain 27 wound around the sprockets 25 and 26. - 特許庁

A sprocket 26 is located between the bearings 22,23. When the second driving machine 24 of the second rotating mechanism 20 is driven, the sprocket 25 fixed to the rotating shaft of the second driving machine 24 rotates, and the sprocket 26 fixed to the second screw shaft 4A via the chain 27 rotates. to rotate. As a result, the second screw 4 is rotated by the second rotating mechanism 20 .

A second driving machine 24 is connected to the control section 6 . The second driving machine 24 incorporates an inverter (not shown), and the control section 6 is configured to be able to control the operation of the second driving machine 24 via the inverter. That is, the controller 6 can control the rotation speed and rotation direction of the second driving machine 24 via the inverter. The second driver 24 can rotate the second screw 4 independently of the first screw 3 . The first driving machine 14 also preferably incorporates an inverter capable of changing the rotation speed and rotation direction of the first driving machine 14 .

Although not shown, the rotating shaft of the second driving device 24 may be connected to the second screw shaft 4A via a speed reducer. Alternatively, the rotating shaft of the second driving machine 24 may be directly connected to the second screw shaft 4A.

The first screw blade 3B extends spirally along the axial direction of the first screw shaft 3A, and the second screw blade 4B extends spirally along the axial direction of the second screw shaft 4A. The total length of the portion of the first screw 3 to which the first screw blades 3B are fixed and the portion of the second screw 4 to which the second screw blades 4B are fixed is the axial length of the screen casing 1. Identical or longer.

A minute gap is formed between the inner surface of the screen casing 1 and the first screw blade 3B, so that the first screw blade 3B can rotate without contacting the screen casing 1. Similarly, a minute gap is formed between the inner surface of the screen casing 1 and the second screw blade 4B, so that the second screw blade 4B can rotate without contacting the screen casing 1. ing.

Sludge introduced into the screen casing 1 from the inlet 2 formed at the upstream end of the screen casing 1 is directed toward the discharge chamber 33 by the rotating first screw blade 3B and the second screw blade 4B (that is, transferred direction D).

In this embodiment, the winding direction (that is, spiral direction) of the second screw blade 4B is opposite to the winding direction of the first screw blade 3B. Therefore, when the sludge input from the input port 2 is sent to the discharge chamber 33, the second screw 4 is rotated in the opposite direction to the first screw 3, as shown in FIG.

In one embodiment, the winding direction of the second screw blade 4B may be the same as the winding direction of the first screw blade 3B. In this case, the second screw 4 is rotated in the same direction as the first screw 3 when sending out the sludge introduced from the inlet 2 to the discharge chamber 33 .

As shown in FIG. 1, the screen casing 1 is divided into a dewatering area 1A in which the first screw 3 is arranged and a plug forming area 1B in which the second screw 4 is arranged. A space in which sludge is transferred in the dewatering area 1A is formed by the inner surface of the screen casing 1, the first screw blades 3B, and the first screw shaft 3A.

The cross-sectional area of this transfer space gradually decreases along the sludge transfer direction D, as shown in FIG. Therefore, as the sludge introduced from the inlet 2 is transferred through this transfer space by the first screw blade 3B, the sludge is compressed and dewatered. Filtrate that has passed through the screen (perforated plate) of the screen casing 1 is recovered by a filtrate receiver 38 arranged below the screen casing 1 . A drain 39 is connected to the filtrate receiver 38 , and the filtrate collected by the filtrate receiver 38 is discharged from the screw press via the drain 39 .

A space in which sludge is transferred in the plug forming area 1B is formed by the inner surface of the screen casing 1, the second screw blades 4B and the second screw shaft 4A. As shown in FIG. 1, the cross-sectional area of this transfer space is constant. In the plug forming area 1B, a plug cake is formed by the sludge (that is, cake) dewatered in the dewatering area 1A. The method of forming the plug cake is as follows.

The sludge introduced from the inlet 2 is transferred toward the second screw 4 (that is, in the transfer direction D) by the rotating first screw blades 3B without remaining in place. The sludge is compressed as it is transferred through the dewatering area 1A, and the liquid contained in the sludge is filtered by the screen casing 1. While the sludge is being transported through the dewatering area 1A of the screen casing 1, the sludge is dewatered into a cake and sent to the plug forming area 1B where the second screw 4 is arranged.

At the beginning of the operation, the second screw 4 is not rotating (that is, stopped), so the cake in the plug forming area 1B is not discharged into the discharge chamber 33 and stays in the plug forming area 1B. The cake gradually accumulates on the second screw 4 and is pressed against the second screw blades 4B by the sludge transferred from the dewatering area 1A to the plug forming area 1B (hereinafter referred to as "subsequent cake").

The cake in the plug forming region 1B is squeezed by being prevented from moving by the second screw blade 4B, and becomes a cake with a low moisture content. This low moisture content cake forms a plug cake that impedes subsequent cake migration. A plug cake formed around the second screw shaft 4A applies back pressure to the subsequent cake, which is further squeezed. Liquid separated from the plug cake in plug forming region 1B is collected by filtrate receiver 38 and discharged from the screw press via drain 39 .

As the operation of the screw press continues, the plug cake is uniformly formed over the entire circumference of the second screw shaft 4A. As a result, a plug cake is formed around the second screw shaft 4A that reliably dams up the succeeding cake. Therefore, even when the subsequent cake has a high moisture content, the subsequent cake can be reliably blocked by the plug cake formed in the plug forming region 1B, so that the subsequent cake can be prevented from flowing sideways. This "single flow" means that subsequent cakes having a higher moisture content than the plug cake are discharged into the discharge chamber 33 directly through the plug forming region 1B.

In the following embodiments, a configuration of a screw press capable of reliably preventing sludge from entering the internal space of the second screw shaft 4A will be described with reference to the drawings.

As described above, the sludge introduced from the inlet 2 is squeezed as it is transported by the first screw blade 3B and the second screw blade 4B. Therefore, the pressed sludge may pass through the sliding bearings 30, 31 (see FIG. 2) fixed to the inner wall 4C of the second screw shaft 4A and enter the internal space of the second screw shaft 4A. Sludge that has entered this internal space may hinder smooth rotation of the first screw 3 and the second screw 4 . Therefore, in the embodiments described below, the screw press has a structure that reliably prevents sludge from entering the internal space of the second screw shaft 4A.

FIG. 3 is a schematic cross-sectional view showing another embodiment of the second screw 4. As shown in FIG. In the present embodiment, members that are the same as or correspond to those in the above-described embodiment are denoted by the same reference numerals, and overlapping descriptions are omitted. As shown in FIG. 3, the second screw 4 has a second screw shaft 4A having a recess into which the first screw shaft 3A of the first screw 3 is inserted. More specifically, the second screw shaft 4A has an end wall 4E formed on the inner wall 4C. The recess is defined by an inner wall 4C and an end wall 4E.

An end wall 4E of the second screw shaft 4A is provided at a reduced diameter portion 4F formed on a wall surface 4D of the second screw shaft 4A. The reduced diameter portion 4F extends from the wall surface 4D toward the bearings 22 and 23 and is supported by the bearings 22 and 23. As shown in FIG. In the embodiment shown in FIG. 3, the end wall 4E is located between the outermost edge 4F-1 of the reduced diameter section 4F and the wall surface 4D; It may be connected to the outermost end 4F-1 of 4F.

As shown in FIG. 3, the tip 3C-1 of the reduced diameter portion 3C of the first screw shaft 3A inserted into the second screw shaft 4A is arranged adjacent to the end wall 4E of the second screw shaft 4A. there is When the diameter-reduced portion 3C is inserted into the second screw shaft 4A, a closed space SP1 is formed between the diameter-reduced portion 3C and the recess of the second screw shaft 4A (that is, the inner wall 4C and the end wall 4E). be.

As shown in FIG. 3, the bearings 30A and 31A are arranged between the first screw shaft 3A of the first screw 3 and the second screw shaft 4A of the second screw 4. As shown in FIG. Each of these bearings 30A and 31A is, for example, a slide bearing. The bearing 30A is arranged adjacent to the wall surface 3D formed on the first screw shaft 3A, and the bearing 31A is arranged adjacent to the tip 3C-1 of the reduced diameter portion 3C.

FIG. 4 is an enlarged view of the bearing 30A. As shown in FIGS. 3 and 4, between the screen casing 1 and the first screw shaft 3A and the second screw shaft 4A, a compression flow path CH1 is formed in which sludge is compressed. The bearing 30A has a through channel 200 that communicates the closed space SP1 formed between the first screw shaft 3A and the second screw shaft 4A with the compression channel CH1.

FIG. 5 is a perspective view of the bearing 30A. In the embodiment shown in FIG. 5, the through passages 200 are grooves formed in the surface of the bearing 30A. The surface of the bearing 30A is a general term for the outer surface 30A-1 and the inner surface 30A-2 of the bearing 30A. Accordingly, through passages 200 may be formed in outer surface 30A-1 of bearing 30A and/or may be formed in inner surface 30A-2 of bearing 30A.

As shown in FIG. 5, the bearing 30A includes a tubular portion 201 extending parallel to the diameter-reduced portion 3C of the first screw shaft 3A, and an annular portion 202 arranged to protrude from the tubular portion 201. . The cylindrical portion 201 and the annular portion 202 are arranged perpendicular to each other. The cylindrical portion 201 is a portion that receives a radial force acting on the first screw shaft 3A (and/or the second screw shaft 4A), and the annular portion 202 is a portion that receives the first screw shaft 3A (and/or the second screw shaft 4A). ) is the part that receives the thrust force acting on

In the embodiment shown in FIG. 5, the through passage 200 is formed in the outer surface 30A-1 of the cylindrical portion 201 and extends in parallel with the axial direction CL, and the first passage 200a is formed in the surface 202b of the annular portion 202. , and a second flow path 200b extending in the radial direction of the annular portion 202 (that is, a direction perpendicular to the axial direction CL), and a third flow formed in the peripheral edge portion 202a of the annular portion 202 and extending in parallel with the axial direction CL. and a path 200c. These first flow path 200a, second flow path 200b, and third flow path 200c are connected to form one flow path. The first flow path 200a is connected to the end surface 201a of the tubular portion 201 .

In this way, the bearing 30A having the through-flow passage 200 allows the sealed space SP1 and the compressed flow passage CH1 to communicate with each other through the through-flow passage 200. Therefore, the pressure in the closed space SP1 becomes the same as the pressure in the compression channel CH1, which is increased by squeezing the sludge. As a result, no pressure difference is generated between the compression channel CH1 and the closed space SP1, and the sludge moving through the compression channel CH1 does not enter the closed space SP1.

In the embodiment shown in FIG. 5, the bearing 30A has a cylindrical portion 201 and an annular portion 202, but the structure of the bearing 30A is not necessarily limited to the embodiment shown in FIG. In one embodiment, bearing 30A may have a cylindrical shape for receiving radial and thrust forces. In this case, the bearing 30A has a through channel 200 extending parallel to its axial direction.

FIG. 6 is a diagram showing another embodiment of the through channel 200. As shown in FIG. As shown in FIG. 6, the through channel 200 may be a through hole formed in the bearing 30A. In the embodiment shown in FIG. 6 , the through channel 200 opens at an end face 201 a of the cylindrical portion 201 and a peripheral edge portion 202 a of the annular portion 202 . Bearing 30A may have both grooves and through holes.

As described above, since the screw press includes the bearing 30A (and the bearing 31A) having the through passage 200, it is possible to prevent sludge from entering the sealed space SP1. In general, a seal member is provided on a bearing (not shown) arranged between the first screw shaft 3A and the second screw shaft 4A to prevent sludge from entering. However, since the seal member is a consumable part, it is necessary to replace the seal member periodically. In order to replace the seal member, it is necessary to perform a large-scale work for removing the first screw shaft 3A from the second screw shaft 4A. According to the embodiment shown in FIGS. 3 to 6, it is possible to prevent the intrusion of sludge without providing a sealing member, so that a large-scale work for exchanging the sealing member can be omitted.

Although not shown, the bearing 31A may have a through channel having a structure similar to that of the through channel 200 . When the through-channel is a groove formed on the surface of the bearing 31A, the through-channel extends parallel to the axial direction CL. When the through channel is a through hole formed in the bearing 31A, the through channel extends parallel to the axial direction CL.

As shown in FIG. 3, the second screw 4 includes a drainage hole 205 formed in the reduced diameter portion 4F of the second screw shaft 4A, and a drainage plug 206 that closes the drainage hole 205. . As described above, by providing the bearing 30A having the through flow path 200, sludge is prevented from entering the sealed space SP1. However, part of the liquid contained in the sludge may enter the closed space SP1 through the through-channel 200 . Therefore, the second screw 4 is provided with a drainage hole 205 and a drainage plug 206 .

Drain hole 205 is arranged in a region between bearing 30A and bearing 31A. When discharging the liquid that has entered the sealed space SP1, the operator operates the second rotating mechanism 20 so that the liquid drain hole 205 is arranged at the lowest portion of the reduced diameter portion 4F. After that, the operator removes the drain plug 206 to drain the liquid out of the screw press through the drain hole 205 . By periodically draining the liquid through the drain holes 205, rust formation is prevented. As a result, the internal space of the screw press can be kept clean.

In one embodiment, the operator may inject a lubricating liquid for lubricating the bearings 30A and 31A into the sealed space SP1 through the drain hole 205. FIG. By injecting the lubricating liquid and closing the drain plug 206, the sealed space SP1 is filled with the lubricating liquid.

FIG. 7 is a view showing a lubricating fluid injection hole 209 formed in the reduced diameter portion 4F of the second screw shaft 4A and an injection plug 210 closing the lubricating fluid injection hole 209. As shown in FIG. As shown in FIG. 7, the second screw 4 includes a lubricating fluid injection hole 209 formed in the reduced diameter portion 4F of the second screw shaft 4A and an injection plug 210 that closes the lubricating fluid injection hole 209. good too.

In the embodiment shown in FIG. 7, the drainage holes 205 and the lubricant injection holes 209 are arranged at regular intervals along the circumferential direction of the reduced diameter portion 4F. is not limited to the embodiment shown in FIG. In one embodiment, the drain hole 205 and the lubricating liquid injection hole 209 may be arranged adjacent to each other along the circumferential direction of the reduced diameter portion 4F. In another embodiment, the drainage hole 205 and the lubricant injection hole 209 may be arranged adjacent to each other along the axial direction CL.

FIG. 8 is a diagram showing a pressure detection device that detects the internal pressure of the sealed space SP1. As shown in FIG. 8, the screw press may further include a pressure sensing device 220 that senses the internal pressure of the closed space SP1. The pressure detection device 220 is arranged inside the sealed space SP1 and electrically connected to the control section 6 . With such a configuration, the controller 6 can monitor the internal pressure of the sealed space SP1.

The above-described embodiments are described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above-described embodiments can be naturally made by those skilled in the art, and the technical idea of the present invention can also be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in its broadest scope in accordance with the technical spirit defined by the claims.

1 screen casing 1A dewatering area 1B plug forming area 2 inlet 3 first screw 3A first screw shaft 3B first screw blade 3C reduced diameter portion 3C-1 tip 3D wall surface 4 second screw 4A second screw shaft 4B second screw Blade 4C Inner wall 4D Wall surface 4E End wall 4F Reduced diameter portion 4F-1 Outermost end 6 Control unit 7 First rotating mechanism 8 Closing wall 10 Water seal devices 11, 12 Bearing 14 First driving machine 15, 16 Sprocket 17 Chain 20 Two-rotation mechanisms 22, 23 Bearings 24 Second driving machines 25, 26 Sprockets 27 Chains 30, 31 Slide bearings 30A, 31A Bearings 30A-1 Outer surface 30A-2 Inner surface 33 Discharge chamber 38 Filtrate receiver 39 Drain 200 Through channel 200a First flow path 200b Second flow path 200c Third flow path 201 Cylindrical portion 201a End surface 202 Annular portion 202a Peripheral edge portion 202b Surface 205 Drainage hole 206 Drainage plug 209 Lubricant injection hole 210 Injection plug 220 Pressure detector CL Axis Direction SP1 Closed space CH1 Compressed flow path

Claims (6)

a filter cylinder into which the liquid inclusions are introduced;
a first screw and a second screw arranged concentrically with the filter cylinder in the filter cylinder for transporting the liquid-containing material in a predetermined transport direction;
a bearing disposed between the first screw and the second screw;
The second screw has a second screw shaft having a recess into which the first screw shaft of the first screw is inserted,
Between the filter cylinder and the first screw shaft and the second screw shaft, a compression flow path is formed in which the liquid containing material is compressed,
The screw press, wherein the bearing has a through channel that communicates a closed space formed between the first screw shaft and the second screw shaft with the compression channel. 2. The screw press according to claim 1, wherein said through passage is a groove formed on the surface of said bearing. 3. The screw press according to claim 1, wherein said through passage is a through hole formed in said bearing. The second screw is
a drainage hole formed in the second screw shaft;
The screw press according to any one of claims 1 to 3, further comprising a drain plug for blocking the drain hole. The second screw is
a lubricant injection hole formed in the second screw shaft;
The screw press according to any one of claims 1 to 4, further comprising an injection plug that closes the lubricating fluid injection hole. The screw press according to any one of claims 1 to 5, further comprising a pressure detection device that detects the internal pressure of the closed space.

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