Screw conveyor

Abstract

To provide a screw conveyor suppressed in deformation of blades when a discharge port is blocked, without impairing discharge performance of a conveying object.SOLUTION: A screw conveyor has an axially rotatable shaft 1 and blades 2 provided spirally along the shaft 1, in a casing 4. One or two or more reinforcing ribs 3 connecting a final step conveying face 2a where faces of the blades 2 do not face with each other in the axial direction in the discharge side face of the blades 2, to the shaft 1 are provided on the final step conveying face 2a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a screw conveyor having spiral blades (screw blades) provided along its axis. [Background technology]

[0002] For example, in the steelmaking process, various raw materials are crushed and used. The purpose of crushing is to improve reactivity by increasing the specific surface area and to improve the homogeneity of the raw materials. To transport these raw materials, for example, a screw conveyor is used.

[0003] The discharge volume of the screw conveyor can be easily adjusted by controlling the rotation speed. In addition, the gas below the screw conveyor can be sealed off by the transported material (also called raw material) inside the casing of the screw conveyor.

[0004] If a blockage occurs in the chute connected to the discharge outlet downstream of the screw conveyor, the material being conveyed cannot be discharged from the screw conveyor. When this happens, the drive motor that rotates the shaft becomes overloaded and the conveyor stops driving. However, there is a time lag between the time the discharge outlet becomes blocked and the time the motor stops due to overload. The rotation of the screw conveyor during this time causes overcompression of the material being conveyed. This overcompression can cause excessive load to act on the downstream portion of the blade (the last stage), which can cause the downstream portion of the blade to bend. If the blade is bent, this bending damage reduces the discharge rate of the blade as it rotates, which can lead to new blockages.

[0005] Here, as a method for reinforcing the blades of a screw conveyor, there are techniques described in Patent Documents 1 and 2, for example. Patent Document 1 describes that a plate-shaped or rod-shaped reinforcing member parallel to the axis is installed on the outer periphery of the blade over the entire length of the blade. Patent Document 2 describes that stripes of hardfacing are provided on the conveying surface of a spiral blade along its radial direction at predetermined intervals in the circumferential direction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-24388 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-189301 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when reinforcing materials are attached to the outer periphery of the blades in the axial direction and over the entire length of the blades as in Patent Document 1, the following problem arises: In Patent Document 1, if raw material adheres to the reinforcing material located on the casing side, the raw material may become caught between the reinforcing material and the casing, or the discharge of raw material located between the blades facing each other in the axial direction may be hindered, causing blockages. Furthermore, the method described in Patent Document 2 merely increases the radial rigidity of the blade itself. In other words, it is not possible to prevent the blade from bending and deforming in the out-of-plane direction (axial direction) relative to the shaft due to an excessive load caused by excessive compression of the raw material. Therefore, with the method described in Patent Document 2, if a large load is applied to the conveying surface of the blade, the blade may bend at the joint surface with the shaft.

[0008] The present invention has been made in view of the above-mentioned points, and aims to provide a screw conveyor that can suppress deformation of the blades when the discharge port is blocked without impairing the discharge performance of the transported material. [Means for solving the problem]

[0009] In order to solve the problem, one aspect of the present invention is a screw conveyor having a rotatable shaft and blades arranged in a spiral along the shaft within a casing, and one or more reinforcing ribs are provided on the final conveying surface of the blades, which is a surface where the blade faces do not face each other in the axial direction, to connect the final conveying surface to the shaft. [Effects of the Invention]

[0010] According to this aspect of the present invention, by connecting the discharge-side blade surface and the shaft with a reinforcing rib, the rigidity of the blade surface at that position against bending moments in the out-of-plane direction (axial direction) is improved. Also, in this aspect of the present invention, the reinforcing rib is provided on a surface where the blade surfaces do not face each other in the axial direction. Therefore, even if the reinforcing rib is provided, the space where the blade surfaces face each other in the axial direction (the space where the transported object is transported) is not partially narrowed. As a result, according to this aspect of the present invention, it is possible to suppress deformation of the blades even if the discharge port is blocked, without impairing the discharge performance of the transported object. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic view partially perspectively illustrating a screw conveyor according to an embodiment of the present invention. [Figure 2] 10A and 10B are schematic diagrams showing other examples of the reinforcing structure of the blade. [Figure 3] 10A and 10B are schematic diagrams showing other examples of the reinforcing structure of the blade. [Figure 4] 10A and 10B are schematic diagrams showing other examples of the reinforcing structure of the blade. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, an embodiment of the present invention will be described with reference to the drawings. (composition) As shown in Figure 1, the screw conveyor has a rotatable shaft 1 and blades 2 (hereinafter also referred to as screw blades 2) arranged in a spiral shape along the shaft 1, inside a casing 4 made of a truss or the like. The shaft 1 is driven by a drive motor 6. The casing 4 has a raw material inlet 5 on the upstream side and a raw material outlet 7 on the downstream side. Examples of the raw materials to be conveyed include powdered materials with low friction, such as feed, powdered coal, etc. However, if wear-resistant materials are used for the casing 4 and the screw blades 2, the screw conveyor can also convey powdered or lumpy materials with friction, such as cement, sand, and limestone.

[0013] In the screw conveyor, raw materials (materials to be conveyed) are fed into the casing 4 through an inlet 5 provided on the upstream side. The fed raw materials are given a propulsive force in the axial direction as the shaft 1 and blades 2 are driven to rotate, and are then conveyed (transported) downstream. The conveyed raw materials are then discharged to the outside through a discharge outlet 7. The surface of the blades 2 that imparts the propulsive force to the raw materials (the surface facing downstream) is the conveying surface. The diameter of the screw blade 2 is, for example, in the range of 50 mm to 2000 mm, and the total length of the screw blade 2 is, for example, in the range of 500 mm to 7000 mm.

[0014] The screw conveyor of this embodiment is provided with one or more reinforcing ribs 3 on the downstream surface of the blade 2, on a final conveying surface where the surfaces of the blades 2 do not face each other in the axial direction (conveying direction). Each reinforcing rib 3 connects the final conveying surface to the shaft 1. The final conveying surface where the surfaces of the blades 2 do not face each other in the axial direction (conveying direction) is a surface portion of the blade 2 extending in the axial direction that is located on the raw material discharge side and faces the discharge side (hereinafter also referred to as the final surface portion 2a). The final surface portion 2a is a final conveying surface that does not face other surfaces of the blade 2 in the axial direction, and is, for example, the final conveying surface of one circumference along the extension direction (circumferential direction) from the downstream end of the blade 2.

[0015] <Reinforcing rib 3> In this embodiment, two or more reinforcing ribs 3 are provided at intervals in the extending direction (circumferential direction) of the blade 2. The reinforcing ribs 3 are provided at intervals of, for example, 45 degrees or more and 180 degrees or less along the circumferential direction. Here, it is desirable that the two or more reinforcing ribs 3 are arranged at equal angular intervals along the circumferential direction to ensure strength and to maintain dynamic balance during rotation. While it is desirable to provide more reinforcing ribs 3 in terms of strength, it is also desirable that the angular intervals between them be 45 degrees or more. If the angular intervals are too small, there is a risk of the raw material becoming clogged between the reinforcing ribs 3.

[0016] The reinforcing rib 3 shown in Fig. 1 is made of a triangular metal plate member. The reinforcing rib 3 is configured so that two adjacent sides are connected to the final surface portion 2a and the shaft 1, respectively. The reinforcing rib 3 is arranged so as to protrude from the final surface portion 2a in the axial direction (discharge side). It may also be arranged so as to protrude at an angle relative to the axial direction.

[0017] The shape of the reinforcing rib 3 may be, for example, a truncated cone-shaped block body (including a hollow body) with a through-hole in the center (symmetrical position with respect to the axis 1) through which the shaft 1 can pass. In this case, the shaft 1 is passed through the through-hole and fixed, and the bottom surface of the truncated cone shape is connected to the final surface. In this case, it is preferable that the bottom surface has a shape that follows the surface of the final surface portion 2a. As shown in FIG. 1, the height of the reinforcing rib 3 in the direction perpendicular to the shaft 1 surface decreases as it moves away from the surface position of the final surface portion 2a to which the reinforcing rib 3 is connected toward the axial direction (discharge side).

[0018] In Fig. 1, the height of the sloped sides of the reinforcing rib 3 in the direction perpendicular to the shaft 1 surface decreases as the distance from the final surface portion 2a increases. Therefore, the sloped sides may have a contour shape that is convex downward in a circular arc shape. The height of the reinforcing rib 3 on the final surface portion 2a side is, for example, smaller than the radius of the final surface portion 2a and equal to or greater than 1 / 2 of the radius, and preferably equal to or greater than 2 / 3 of the radius. The reinforcing rib 3 is made of, for example, steel.

[0019] <Another example of reinforcing rib 3> (1) As shown in Fig. 2, an extension member 8 (second reinforcing rib) may be provided between the reinforcing rib 3 and the surface portion of the final surface portion 2a to which the reinforcing rib 3 is connected. The extension member 8 is provided so as to be connected to the surface portion and extend in the radial direction (height direction) of the final stage conveying surface. The extension member 8 may be, for example, rod-shaped or plate-shaped. In this configuration, the extension member 8 is fixed in the radial direction along the final conveying surface 2a. The end of the extension member 8 (the end on the shaft 1 side) may or may not be connected to the shaft 1. Furthermore, the extension member 8 and the shaft 1 are connected by a reinforcing rib 3 . In this example, the provision of the extension member 8 allows the height of the reinforcing rib 3 relative to the surface of the shaft 1 to be relatively low. For example, the height of the reinforcing rib 3 relative to the surface of the shaft 1 is set to ⅔ or less and ⅓ or more of the radius of the final surface portion 2a. This allows the amount of raw material adhering to the reinforcing rib 3 to be reduced.

[0020] (2) In the above embodiment, the reinforcing rib 3 is made of a plate material. However, the shape of the reinforcing material is not limited to a flat plate shape. For example, the reinforcing rib 3 is shown as being made of a rod 10 as shown in Fig. 3. In this case, the rod 10 is configured to connect the shaft 1 to a radially intermediate position of the final surface portion 2a. That is, one end of the reinforcing rib 3 made of the rod body 10 is connected to a radially intermediate position of the final surface portion 2a and extends (protrudes) in a direction away from the final surface portion 2a. The other end of the reinforcing rib 3 is connected to the surface of the shaft 1. The height of one end of the reinforcing rib 3 (the connection portion to the final surface portion 2a) is, for example, smaller than the radius of the final surface portion 2a and at least 1 / 2 of the radius, preferably at least 2 / 3 of the radius. In this modification, the height of the reinforcing rib 3 in the direction perpendicular to the axis relative to the surface of the shaft 1 decreases as it moves away from the surface position of the final surface portion 2a to which the reinforcing rib 3 is connected in the axial direction (discharge side).

[0021] Also, as in variant (1), an extension member 8 (second reinforcing rib) may be interposed between the reinforcing rib 3 made of a rod and the final surface portion 2a (see FIG. 4). In this case, as in variant (1), it is possible to reduce the height of one end side (final surface portion 2a side) of the reinforcing rib 3. For example, it is possible to make the height of one end side of the reinforcing rib 3 relative to the surface of the shaft 1, for example, 2 / 3 or less of the radius of the final surface portion 2a. However, it is better to make it 1 / 3 or more, preferably 1 / 2 or more.

[0022] (3) The reinforcing rib 3 may be in the shape of a square plate or the like, and is not limited to any particular shape. However, it is preferable that the height of the reinforcing rib 3 in the direction perpendicular to the axis relative to the surface of the shaft 1 decreases as it moves away in the axial direction (discharge side) from the surface position of the final surface portion 2a to which the reinforcing rib 3 is connected, in order to further suppress the obstruction of the transport of the transported raw material.

[0023] (Operation etc.) In this embodiment, reinforcing ribs 3 are provided on the final conveying surface (surface facing the discharge direction) of the blade 2 to increase the axial bending rigidity of the final conveying surface. This improves the axial bending rigidity (particularly rigidity against the load applied from the discharge side) of the portion of the blade 2 close to the discharge port 7. Even when reinforcing ribs 3 are provided, the height of the reinforcing ribs 3 is set lower the further away from the surface of the blade 2 (final surface portion 2a), thereby reducing the effect of providing the reinforcing ribs 3 on the dischargeability of the raw material. In this embodiment, the reinforcing ribs 3 are provided on the surfaces of the blades that do not face each other in the axial direction. Therefore, even if the reinforcing ribs 3 are provided, the space where the blade surfaces face each other in the axial direction (the space in which the transported object is transported) is not partially narrowed. As a result, the screw conveyor of this embodiment has the function of preventing deformation of the screw blades 2 when the discharge port 7 is blocked without impairing discharge performance.

[0024] <Mechanism to prevent bending damage to screw blades when the outlet is blocked> The mechanism for preventing bending damage to the screw blade 2 when the outlet 7 is blocked in the screw conveyor of this embodiment will be described. The space between the blades 2 in the axial direction where the surfaces of the blades 2 face each other is called the "blade gap." The screw conveyor transports raw materials inside the casing 4 by rotating the shaft 1 and screw blades 2 using a drive motor 6. If a reinforcing material is installed on the non-conveying surface of the screw blades 2, the volume between the screw blades will decrease due to the material adhering to the reinforcing material, which may cause compression of the transported raw material and lead to blockage.

[0025] In contrast, in this embodiment, reinforcing ribs 3 are not provided between the blades, but are instead provided on the conveying surface located at the very end of the screw blade 2. In other words, providing reinforcing ribs 3 between the blades prevents material compression between the blades. As a result, in this embodiment, material continuously conveyed through the spaces between the spiral screw blades is sequentially discharged from the discharge port 7. Even if material adheres to reinforcing ribs 3 that are not between the blades, material compression between the blades and blockage of the screw conveyor are suppressed. Furthermore, even if the discharge port 7 provided in the casing 4 is blocked and excessive compression of the raw material occurs on the downstream side (discharge side) of the casing 4, the reinforcing rib 3 prevents the screw flight 2 from being deformed.

[0026] As described above, in the screw conveyor of this embodiment, there are no reinforcing portions between the blades. This reduces the risk of blockages occurring due to material adhering to the reinforcing portions, which would prevent material from being discharged between the screw blades. In addition, the reinforcing rib 3 increases the bending rigidity of the blade 2 on the discharge side, preventing damage to the blade 2, such as bending at the joint with the shaft 1.

[0027] (others) The present disclosure may also have the following configuration. (1) A screw conveyor in which a rotatable shaft and blades spirally arranged along the shaft are provided within a casing, One or more reinforcing ribs are provided on the final conveying surface of the blade, which is a surface where the blade surfaces do not face each other in the axial direction, to connect the final conveying surface and the shaft. A screw conveyor characterized by: (2) Two or more of the reinforcing ribs are provided at intervals in the extending direction of the blade. (3) The height of the reinforcing rib in the direction perpendicular to the axis relative to the surface of the shaft decreases as the reinforcing rib moves away from the surface portion of the final-stage conveying surface to which the reinforcing rib is connected in the axial direction. (4) The reinforcing rib is made of a triangular plate member, and two adjacent sides are connected to the final stage conveying surface and the shaft, respectively. (5) An extension member is interposed between the reinforcing rib and the final stage conveying surface of the blade to which the reinforcing rib is connected, the extension member being connected to the final stage conveying surface of the blade and extending in the radial direction of the final stage conveying surface. (6) The height of the reinforcing rib relative to the surface of the shaft is 2 / 3 or less of the height of the conveying surface of the final stage of the blade. (7) The reinforcing rib is made of a rod that connects the shaft to a radially intermediate position of the final stage conveying surface. (8) Between the reinforcing rib and the final stage conveying surface to which the reinforcing rib is connected, an extension member is interposed, which is connected to the final stage conveying surface and extends in the radial direction of the final stage conveying surface. (9) The height of the reinforcing rib relative to the surface of the shaft is 2 / 3 or less of the height of the conveying surface of the final stage of the blade. [Example]

[0028] Next, an example based on this embodiment will be described. Example 1 In this example, the powdered coal was transported by the screw conveyor shown in FIG. The screw conveyor of this Example 1 has a shaft 1 with a length of 3800 mm and a diameter of 160 mm, and a screw blade 2 with a diameter of 530 mm and a plate thickness of 6 mm. In addition, a reinforcing rib 3 as shown in Figure 1 is attached to the final stage conveying surface of the screw blade 2. Three reinforcing ribs 3 are provided at 90° intervals in the extending direction of the blade 2 (the rotating direction of the blade 2). In this embodiment, pulverized coal was continuously fed from the feeding port 5. Also, by rotating the motor 6 that rotates the shaft 1 at 5 to 20 revolutions per minute, the raw material was pushed out in the conveying direction by the screw blade 2, and the raw material was sequentially discharged from the discharge port 7.

[0029] (Comparative Example) The screw conveyor of the comparative example had the same configuration as that of Example 1, except that the reinforcing rib 3 was not provided.

[0030] (evaluation) If a blockage occurs at the discharge outlet 7, the shaft 1 will continue to rotate for a while until the motor 6 stops due to overload, and the screw blade 2 will also rotate accordingly until the overload stops. If the discharge outlet 7 is then blocked by the raw material, the raw material will be over-compressed between the last stage of the screw blade 2 and the discharge outlet 7. If over-compression occurs, the reaction force may cause bending damage to the last stage of the screw blade 2. Once bending damage occurs in the blade 2, a section will be created where the pitch between the blades is narrow, so the conveying resistance of the screw conveyor will increase even after the blockage at the discharge outlet 7 is resolved, and in some cases a blockage will occur. Therefore, when the discharge port 7 is blocked, restarting the system requires repair work on the screw blade 2, which takes a very long time.

[0031] In the screw conveyors of Example 1 and Comparative Example, the discharge port 7 was artificially blocked. At this time, in the screw conveyor of Example 1, no bending damage occurred in the final stage portion of the screw flight 2. On the other hand, in the screw conveyor of the comparative example, bending damage occurred in the final stage portion of the screw flight 2. Furthermore, when the pseudo-blockage was removed and operation was resumed, blockage occurred in a short time in the comparative example, whereas in Example 1, no blockage occurred and operation continued normally.

[0032] As described above, it was found that the screw conveyor according to the present invention can prevent damage to the screw flight 2 when the discharge port 7 is blocked. Therefore, even if a blockage occurs in the screw conveyor according to the present invention, it can be quickly restarted after cleaning. Furthermore, it was found that even if the reinforcing rib 3 is installed on the final stage conveying surface, it does not hinder the screw from conveying raw materials. [Explanation of symbols]

[0033] 1 axis 2 Feathers 2a Final surface (final stage conveying surface) 3 Reinforcing ribs 4 Casing 5 Inlet 6 Drive motor 7 Outlet 8 Extension member 10 Rod

Claims

1. A screw conveyor having a rotatable shaft and blades spirally arranged along the shaft within a casing, one or more reinforcing ribs are provided on a final stage conveying surface of the blade, which is a surface where the surfaces of the blades do not face each other in the axial direction, to connect the final stage conveying surface and the shaft; The height of the reinforcing rib in the direction perpendicular to the axis relative to the surface of the shaft decreases as the reinforcing rib moves away from the surface portion of the final stage conveying surface to which the reinforcing rib is connected in the axial direction. A screw conveyor characterized by:

2. Two or more of the reinforcing ribs are provided at intervals in the extending direction of the blade.

2. The screw conveyor according to claim 1.

3. The reinforcing rib is made of a triangular plate member, and two adjacent sides are connected to the final stage conveying surface and the shaft, respectively.

2. The screw conveyor according to claim 1.

4. an extending member connected to the final stage conveying surface of the blade and extending in a radial direction of the final stage conveying surface is interposed between the reinforcing rib and the final stage conveying surface of the blade to which the reinforcing rib is connected; The screw conveyor according to any one of claims 1 to 3.

5. The height of the reinforcing rib relative to the surface of the shaft is 2 / 3 or less of the height of the final stage conveying surface of the blade.

5. The screw conveyor according to claim 4.

6. The reinforcing rib is composed of a rod body connecting a radially intermediate position of the final stage conveying surface and the shaft, 3. A screw conveyor according to claim 1 or 2.

7. An extension member is interposed between the reinforcing rib and the final stage conveying surface to which the reinforcing rib is connected, the extension member being connected to the final stage conveying surface and extending in the radial direction of the final stage conveying surface.

7. The screw conveyor according to claim 6.

8. The height of the reinforcing rib relative to the surface of the shaft is 2 / 3 or less of the height of the conveying surface of the final stage of the blade.

8. The screw conveyor according to claim 7.

9. A screw conveyor having a rotatable shaft and blades spirally arranged along the shaft within a casing, one or more reinforcing ribs are provided on a final stage conveying surface of the blade, which is a surface where the surfaces of the blades do not face each other in the axial direction, to connect the final stage conveying surface and the shaft; an extending member connected to the final stage conveying surface of the blade and extending in a radial direction of the final stage conveying surface is interposed between the reinforcing rib and the final stage conveying surface of the blade to which the reinforcing rib is connected; A screw conveyor characterized by:

10. The reinforcing ribs are provided at least two apart in the extension direction of the blade.

10. The screw conveyor according to claim 9.

11. The height of the reinforcing rib relative to the surface of the shaft is 2 / 3 or less of the height of the final stage conveying surface of the blade.

11. The screw conveyor according to claim 9 or 10.

12. A screw conveyor having a rotatable shaft and blades spirally arranged along the shaft within a casing, one or more reinforcing ribs are provided on a final stage conveying surface of the blade, which is a surface where the surfaces of the blades do not face each other in the axial direction, to connect the final stage conveying surface and the shaft; The reinforcing rib is composed of a rod body connecting a radially intermediate position of the final stage conveying surface and the shaft. A screw conveyor characterized by:

13. The reinforcing ribs are provided at least two apart in the extension direction of the blade, 13. The screw conveyor according to claim 12.

14. Between the reinforcing rib and the final-stage conveying surface to which the reinforcing rib is connected, an extending member is interposed, the extending member being connected to the final-stage conveying surface and extending in a radial direction of the final-stage conveying surface.

14. The screw conveyor according to claim 12 or 13.

15. The height of the reinforcing rib relative to the surface of the shaft is 2 / 3 or less of the height of the final stage conveying surface of the blade.

15. The screw conveyor according to claim 14.

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