JP6876860B1 - Screw press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw press capable of sufficiently maintaining a scraping ability of a scraper for a long period of time. SOLUTION: This is a screw press in which a rotatable screw shaft is inserted inside a tubular screen 5 and a spiral screw blade 7 is provided on an outer peripheral surface of the screw shaft, and is outside the radial direction of the screw blade 7. An elastically deformable scraper 17 that slides into the inner surface of the screen 5 in a curved posture is provided on the peripheral edge, and the scraper 17 is urged on the curved side in the restoring direction C to return the scraper 17 from the curved posture to the standing posture. An elastic member 19 is provided, and the elastic member 19 is separated inward in the radial direction D from the inner surface of the screen 5. [Selection diagram] Fig. 3

Description

The present invention relates to a screw press used for dehydrating an anhydride such as sewage sludge and industrial wastewater sludge.

Conventionally, as a screw press of this type, as shown in FIG. 11, for example, a rotatable screw shaft is inserted into a tubular screen 101, and a spiral screw blade 103 is provided on the outer peripheral surface of the screw shaft. There is something.
A sludge supply port is provided at the upstream end of the screen 101, and a sludge discharge port is provided at the downstream end of the screen 101.

A rubber elastically deformable scraper 106 is provided on the outer peripheral edge of the screw blade 103 in the radial direction so as to be in sliding contact with the inner surface of the screen 101 in a curved posture in a bow shape.

A metal holding plate 107 is provided on the curved side (upstream side) of the scraper 106, and the scraper 106 is sandwiched between the screw blade 103 and the holding plate 107, and the screw blade is sandwiched between a plurality of bolts 108 and nuts 109. It is attached to 103.

According to this, the screw blade 103 is rotated by rotating the screw shaft. The sludge supplied into the screen 101 from the sludge supply port is pressure-filtered while being sent from the upstream side to the downstream side by the rotation of the screw blade 103. The filtrate generated at this time passes through the through hole 112 of the screen 101 and is discharged to the lower side of the screen 101, and the dehydrated sludge is discharged as a cake (dehydrated sludge) from the sludge discharge port.

Further, when the screw blade 103 is rotating, the scraper 106 is in sliding contact with the inner surface of the screen 101 in a curved state in a bow shape, so that the sludge on the inner surface of the screen 101 is scraped off by the scraper 106, and the sludge is scraped off by the scraper 106. It can be prevented from adhering to.

The gap reduction portion 115a (see FIG. 12) in which the gap 115 between the screw blade 103 and the screen 101 is reduced or the gap expansion portion 115b is enlarged due to the outer diameter tolerance of the screw blade 103 and the inner diameter tolerance of the screen 101 at the time of manufacture. (See FIG. 13) may be present in the circumferential direction of the screen 101.

A screw press provided with the scraper 106 as described above is described in, for example, Patent Document 1 below.

Patent No. 5631067

However, in the above-mentioned conventional type, there is a problem that the scraper 106 deteriorates over time, sagging due to permanent strain occurs, and the restoring force of the scraper 106 to return from the curved posture to the standing posture decreases.

In particular, as shown in FIG. 12, when the restoring force of the scraper 106 is reduced while the scraper 106 is curved at a steep angle in the gap reduction portion 115a and the scraper 106 is worn out, the scraper 106 rotates together with the screw blade 103. Then, when the scraped portion of the scraper 106 rotates from the gap reducing portion 115a to the gap expanding portion 115b shown in FIG. 13, it does not sufficiently slide into the inner surface of the screen 101, and the scraping ability of the scraper 106 is insufficient. There is a problem of putting it away.

Further, in the above patent document, as shown in FIG. 14, two scrapers 106 and 117 are overlapped and sandwiched between the screw blade 103 and the pressing plate 107, and the screw blade is formed by a plurality of bolts 108 and nuts 109. A screw press attached to 103 is disclosed.

However, since the two scrapers 106 and 117 are in sliding contact with the inner surface of the screen 101 in a state of being curved in a bow shape, there is a problem that the frictional resistance when rotating the screw blade 103 is increased.

An object of the present invention is to provide a screw press capable of sufficiently maintaining the scraping ability of a scraper for a long period of time.

In order to achieve the above object, the first invention is a screw press in which a rotatable screw shaft is inserted in a tubular screen and a spiral screw blade is provided on the outer peripheral surface of the screw shaft.
An elastically deformable scraper is provided on the outer peripheral edge of the screw blade in the radial direction to change the posture from an upright posture to a curved posture by contacting the inner surface of the screen.
The scraper slides against the inner surface of the screen on the opposite side of the curved side.
An elastic member is provided on the curved side of the scraper to urge the scraper in the restoring direction to return it from the curved posture to the upright posture.
The elastic member is separated from the inner surface of the screen in the radial direction.

According to this, since the elastic member urges the scraper in the restoring direction, the scraper is apparently less likely to be permanently distorted, and the scraping ability of the scraper is sufficiently maintained for a long period of time. As a result, the replacement life of the scraper can be extended.

Further, since the elastic member is not in contact with the inner surface of the screen, it is possible to prevent an increase in frictional resistance when rotating the screw blades.

In the screw press in the second invention, the elastic member is made of rubber.

The screw press in the third invention has an elastic member having a compression set of 30% or less.

According to this, the elastic member is unlikely to cause permanent strain.

In the screw press in the fourth invention, the elastic member is a spring.

In the screw press in the fifth invention, the scraper is made of a thermoplastic elastomer resin.

In the screw press in the sixth invention, a pressing member is provided on the curved side of the scraper.
The scraper and the elastic member are attached by being sandwiched between the screw blade and the holding member.
The outer peripheral end portion of the elastic member is located outside the outer peripheral end portion of the pressing member in the radial direction.

According to this, the elastic member can be curved together with the scraper at the outer portion in the radial direction from the outer peripheral end portion of the pressing member. As a result, the urging force of the elastic member for urging the scraper in the restoring direction is increased, and the scraping ability of the scraper is improved.

As described above, according to the present invention, the scraping ability of the scraper can be sufficiently maintained for a long period of time, and the replacement life of the scraper can be extended.

It is a partial notch side view of the screw press in the 1st Embodiment of this invention. It is a view of XX arrow in FIG. It is an enlarged cross-sectional view showing how the scraper of the screw press is in sliding contact with the inner surface of the screen. The same is an enlarged cross-sectional view showing the state of the scraper when the screen of the screw press is not provided. The same is an enlarged cross-sectional view showing a state in which the scraper of the screw press is in sliding contact with the inner surface of the screen, and shows a state in which the distance between the screw blade and the screen is reduced. The same is an enlarged cross-sectional view showing a state in which the scraper of the screw press is in sliding contact with the inner surface of the screen, and shows a state in which the distance between the screw blade and the screen is increased. It is an enlarged cross-sectional view which shows the state that the scraper of the screw press in the 2nd Embodiment of this invention is in sliding contact with the inner surface of a screen. It is an enlarged cross-sectional view which shows the state that the scraper of the screw press in 3rd Embodiment of this invention is in sliding contact with the inner surface of a screen. FIG. 8 is a view taken along the line XX in FIG. FIG. 5 is an enlarged cross-sectional view showing a state in which a screw press scraper according to a fourth embodiment of the present invention is in sliding contact with an inner surface of a screen. FIG. 5 is an enlarged cross-sectional view showing a state in which a scraper of a conventional screw press is in sliding contact with the inner surface of a screen. The same is an enlarged cross-sectional view showing a state in which the scraper of the screw press is in sliding contact with the inner surface of the screen, and shows a state in which the distance between the screw blade and the screen is reduced. The same is an enlarged cross-sectional view showing a state in which the scraper of the screw press is in sliding contact with the inner surface of the screen, and shows a state in which the distance between the screw blade and the screen is increased. The same is an enlarged cross-sectional view showing how the scraper of the screw press is in sliding contact with the inner surface of the screen, and shows an example in which two scrapers are overlapped.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)
In the first embodiment, as shown in FIGS. 1 and 2, reference numeral 1 denotes a uniaxial screw press for dehydrating sludge 2, which is an example of an object to be dehydrated. The screw press 1 includes a cylindrical screen 5 supported by a main body frame 4, a rotatable screw shaft 6 inserted in the screen 5, a rotary drive device 28 for rotating the screw shaft 6, and a screw. It is provided with a spiral screw blade 7 provided on the outer peripheral surface of the shaft 6.

A large number of through holes 8 are formed in the screen 5. A sludge supply port 9 (an example of a dehydrated substance supply section) is provided at one end of the screen 5, and a sludge discharge port 10 (an example of a dehydrated substance discharge section) is provided at the other end of the screen 5. The sludge supply port 9 side is the upstream side, and the sludge discharge port 10 side is the downstream side.

The screw shaft 6 is a tapered shaft having a larger diameter toward the downstream side (sludge discharge port 10 side). A single screw blade 7 is provided on the screw shaft 6, and the pitch P of the screw blade 7 is set to an equal pitch. As a result, the volume of the filter chamber per pitch of the screw blades 7 is reduced toward the downstream side (sludge discharge port 10 side).

A back pressure plate 11 is arranged at the sludge discharge port 10. The back pressure plate 11 is movable in the axial direction of the screw shaft 6 by the cylinder device 12, and controls the dewatering force (squeezing force) by adjusting the pressure acting toward the sludge discharge port 10. ..

As shown in FIG. 3, the surface facing the upstream side (sludge supply port 9 side) of the screw blade 7 is the back surface A, and the surface facing the downstream side (sludge discharge port 10 side) of the screw blade 7 is the front surface B. On the back surface A of the radial outer peripheral edge of the screw blade 7, an elastically deformable scraper 17 that slides into the inner surface of the screen 5 in a bow-shaped curved posture toward the upstream side (sludge supply port 9 side) is provided. ..

The scraper 17 is made of a thermoplastic elastomer resin and is formed in a spiral shape when viewed from the upstream side. An elastic member 19 for urging the scraper 17 in the restoration direction C is provided on the curved side (upstream side) of the scraper 17. As shown in FIG. 4, in the state where the screen 5 is not provided, the scraper 17 is in an outwardly standing posture in the radial direction D, and the restoration direction C is a return from the curved posture of the scraper 17 to the standing posture. The direction to try.

The elastic member 19 is a rubber strip formed in a spiral shape when viewed from the upstream side. As the rubber, for example, chloroprene rubber having a compression set of 30% (70 ° C., 24 hours) or less is used. The outer peripheral end portion 19a of the elastic member 19 is separated inward in the radial direction D from the inner surface of the screen 5.

A presser plate 21 (an example of a presser member) is provided on the curved side (upstream side) of the scraper 17. The presser plate 21 is a metal plate such as stainless steel that is spirally formed when viewed from the upstream side. The scraper 17 and the elastic member 19 are sandwiched between the screw blade 7 and the holding plate 21, and are attached by a plurality of bolts 23 and nuts 24. The scraper 17 is adjacent to the screw blade 7, the elastic member 19 is adjacent to the pressing plate 21, and the bolt 23 penetrates the screw blade 7, the scraper 17, the elastic member 19, and the pressing plate 21 in the thickness direction E. doing.

The outer peripheral end portion 19a of the elastic member 19 is located outside the outer peripheral end portion 21a of the pressing plate 21 in the radial direction D.

It should be noted that the gap 31a (see FIG. 5) in which the gap 31 between the screw blade 7 and the screen 5 is reduced or the gap expansion portion 31b is expanded due to the outer diameter tolerance of the screw blade 7 and the inner diameter tolerance of the screen 5 at the time of manufacture. (See FIG. 6) may be present in the circumferential direction G of the screen 5.

The operation in the above configuration will be described below.

The screw blade 7 rotates with the rotation of the screw shaft 6, and the sludge 2 supplied into the screen 5 from the sludge supply port 9 is filtered and dehydrated while being sent from the upstream side to the downstream side by the rotation of the screw blade 7. The filtrate 25 generated at this time passes through the through hole 8 of the screen 5 and is discharged to the lower side of the screen 5, and the dehydrated sludge 2 is discharged from the sludge discharge port 10 as a cake 29 (dehydrated sludge).

At this time, as shown in FIG. 3, since the scraper 17 is in sliding contact with the inner surface of the screen 5, the sludge 2 on the inner surface of the screen 5 is scraped off by the scraper 17 to prevent the sludge 2 from adhering to the inner surface of the screen 5. can do.

At this time, since the elastic member 19 urges the scraper 17 in the restoration direction C, the scraper 17 is apparently less likely to be permanently distorted, and the scraping ability of the scraper 17 is sufficiently maintained for a long period of time. As a result, the replacement life of the scraper 17 can be extended.

Further, since the outer peripheral end portion 19a of the elastic member 19 is located outside the outer peripheral end portion 21a of the presser plate 21 in the radial direction D, the elastic member 19 is radially larger than the outer peripheral end portion 21a of the presser plate 21. In the outer portion of D, it can be curved upstream with the scraper 17. As a result, as shown in FIG. 5, even if the scraper 17 is curved at a steep angle at the gap reduction portion 31a, the scraper 17 is sandwiched between the inner surface of the screen 5 and the outer peripheral end portion 21a of the pressing plate 21. It can be prevented from being damaged.

Further, when the scraper 17 rotates from the gap reducing portion 31a to the gap expanding portion 31b shown in FIG. 6, the curved elastic member 19 urges the scraper 17 that has been curved at a steep angle in the restoration direction C, thereby causing the scraper. 17 is sufficiently slidable with the inner surface of the screen 5, and the scraping ability of the scraper 17 is improved.

Further, since the elastic member 19 is not in contact with the inner surface of the screen 5, it is possible to suppress an increase in frictional resistance when rotating the screw blade 7.

(Other embodiments)
In the first embodiment, as shown in FIG. 3, a rubber strip is used as the elastic member 19, but the present invention is not limited to this, and for example, as the second embodiment, FIG. As shown in 7, a leaf spring formed spirally when viewed from the upstream side may be used for the elastic member 19.

Further, as the third embodiment, as shown in FIGS. 8 and 9, the elastic member 19 may be composed of a plurality of columnar members 33 made of rubber. In this case, a plurality of cylindrical spacers 34 are provided between the scraper 17 and the pressing plate 21, and the bolts 23 are inserted through the spacers 34.

Further, as a fourth embodiment, as shown in FIG. 10, the elastic member 19 may be composed of a plurality of coil springs 36.

In each of the above embodiments, as shown in FIG. 1, the scraper 17 or the like is applied to the uniaxial screw press 1, but the scraper 17 or the like is similarly applied to the biaxial screw press. You may.

In each of the above embodiments, as the screw press 1, the screw shaft 6 is a tapered shaft having a larger diameter toward the downstream side, and the screw blades 7 are provided in a single row at equal pitches. If the pitch P of the screw blades 7 is narrower toward the downstream side, the screw shaft 6 does not need to be tapered. Further, the screw press 7 may be a screw press in which two or more screw blades 7 are provided on the screw shaft 6.

1 Screw press 5 Screen 6 Screw shaft 7 Screw blade 17 Scraper 19 Elastic member 19a Outer peripheral end of elastic member 21 Presser plate (presser member)
21a Outer peripheral end of presser plate 36 Coil spring C Restoration direction D Radial direction

Claims (6)

A screw press in which a rotatable screw shaft is inserted into a tubular screen and spiral screw blades are provided on the outer peripheral surface of the screw shaft.
An elastically deformable scraper is provided on the outer peripheral edge of the screw blade in the radial direction to change the posture from an upright posture to a curved posture by contacting the inner surface of the screen.
The scraper slides against the inner surface of the screen on the opposite side of the curved side.
An elastic member is provided on the curved side of the scraper to urge the scraper in the restoring direction to return it from the curved posture to the upright posture.
A screw press characterized in that the elastic member is separated radially inward from the inner surface of the screen. The screw press according to claim 1, wherein the elastic member is made of rubber. The screw press according to claim 2, wherein the elastic member has a compression set of 30% or less. The screw press according to claim 1, wherein the elastic member is a spring. The screw press according to any one of claims 1 to 4, wherein the scraper is made of a thermoplastic elastomer resin. A holding member is provided on the curved side of the scraper,
The scraper and the elastic member are attached by being sandwiched between the screw blade and the holding member.
The screw press according to any one of claims 1 to 5, wherein the outer peripheral end portion of the elastic member is located outside the outer peripheral end portion of the pressing member in the radial direction.

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