Inlet funnel for supplying bulk material into a screw machine

Abstract

An inlet funnel (3) for supplying powdery bulk material (P) into a screw machine (2) comprises a funnel wall (22) which delimits the funnel interior (23). The inlet funnel (3) comprises a stirring unit (30) having a stirrer (31) which is at least partly situated in the funnel interior (23) and can be rotationally driven about a rotational axis (33) by means of a drive (32). The stirrer (31) has a frame-like design in order to detach the bulk material (P) from the funnel wall (22) and to break up bulk material bridges.

Description

[0001] Inlet hopper for feeding bulk material into a screw conveyor

[0002] The content of the German patent application DE 10 2024 211 427.8 is incorporated herein by reference.

[0003] The invention relates to an inlet hopper for feeding bulk material into a screw conveyor. Furthermore, the invention relates to a screw conveyor-inlet hopper arrangement with such an inlet hopper and a method for operating such a screw conveyor-inlet hopper arrangement. The bulk material is, in particular, powdered bulk material.

[0004] From WO 02 / 100624 Al (corresponding to US 2004 / 0202744 Al) a device for filling a screw conveyor is known. The screw conveyor is used for processing pre-shredded plastic material, in particular PET. The device comprises a receiving hopper for the plastic material to be processed. The receiving hopper has a discharge opening that leads into a filling opening in the housing of the screw conveyor. A shaft is arranged in the receiving hopper, to which rod-shaped tools are attached. The shaft is rotatable about a vertical axis of rotation by means of a drive motor. Cutting edges for shredding the plastic material can be arranged on the tools. Rotation of the tools prevents the plastic material from clumping together.

[0005] The invention is based on the objective of creating an inlet hopper that enables the simple and reliable feeding of bulk material, in particular powdered bulk material, into a screw conveyor.

[0006] This problem is solved by an inlet hopper with the features of claim 1. According to the invention, the agitator is designed in a frame-like form. This frame-like design allows the agitator, on the one hand, to detach the bulk material, particularly the powdered bulk material, from the hopper wall and, on the other hand, to break up bulk material bridges that the bulk material, particularly the powdered bulk material, forms. This prevents the build-up of powder layers several centimeters thick and the formation of bulk material bridges that, when falling or collapsing, lead to significant fluctuations in the feeding of the powdered bulk material into the screw conveyor. Due to its frame-like design, the agitator has a simple construction and, during rotary operation, ensures a uniform feeding of the bulk material into the screw conveyor in a simple and reliable manner. The agitator is also robust and requires low torque for its rotation.

[0007] The inlet hopper includes, in particular, a hopper lid. The hopper lid is arranged, in particular, on the hopper wall and, together with the hopper wall, at least partially delimits the interior of the hopper. The hopper lid can be made in one piece or in multiple pieces. If the hopper lid has several hopper lid components, these can be mounted and / or dismounted separately. This allows, for example, a hopper lid component on which the drive is not located to be easily removed for cleaning the inlet hopper. Preferably, the hopper lid incorporates at least one feed opening for feeding the bulk material. For a number N of at least one feed opening, preferably: 1 < N < 6, in particular 2 < N < 5, and in particular 2 < N < 3. Preferably, the respective feed opening is formed in the hopper lid.The drive mechanism for rotating the stirrer is attached, in particular, to the hopper wall and / or the hopper lid. The drive mechanism preferably comprises an electric drive motor. The inlet hopper preferably includes at least one cleaning opening. This at least one cleaning opening can be located in the hopper lid and / or in the hopper wall.

[0008] The discharge opening serves to remove the bulk material from the hopper interior and to feed the bulk material into a screw conveyor. Preferably, the inlet hopper has exactly one discharge opening. The discharge opening is preferably circular or rectangular. Preferably, the discharge opening has a free cross-sectional area AF, where in particular the following applies: 10 cm² 2 < AF < 2,500 cm 2 , especially 25 cm 2 < AF < 1,000 cm 2 , and especially 100 cm 2 < AF < 500 cm 2 .

[0009] Preferably, the inlet hopper includes a mounting section for connecting it to a housing of the screw machine. The mounting section is arranged, in particular, around the discharge opening and connected to the hopper wall. Preferably, the mounting section includes a mounting flange that is connected to the hopper wall. The hopper wall is preferably formed in one piece.

[0010] The axis of rotation can run parallel to the inlet direction or transversely, in particular perpendicularly, to the inlet direction. If the axis of rotation runs parallel to the inlet direction, it is vertical, i.e., perpendicular to the free cross-sectional area of ​​the discharge opening. If the axis of rotation is perpendicular to the inlet direction, it is horizontal, i.e., parallel to the free cross-sectional area of ​​the discharge opening.

[0011] An inlet hopper according to claim 2 ensures simple and reliable feeding of bulk material into a screw conveyor. The at least one impeller is detachably and / or permanently attached to the shaft. The at least one impeller extends radially to the shaft. The at least one impeller is frame-shaped and / or is frame-shaped together with the shaft. This causes the bulk material, especially powdered bulk material, to be detached from the hopper wall during rotary operation of the impeller, and any bulk material bridges that form to be broken up. For a number M of at least one impeller, the following applies in particular: 1 < M < 8, in particular 2 < M < 4, and in particular 2 < M < 3. Preferably, several impellers are distributed around the shaft at equal angular intervals. With an even number of impellers, in particular, two impellers are arranged opposite each other, i.e., at an angular interval of 180° around the axis of rotation.The at least one agitator blade, in particular the respective agitator blade, forms a closed circumferential contour, especially itself and / or together with the shaft.

[0012] An inlet hopper according to claim 3 ensures simple and reliable feeding of bulk material into a screw conveyor. The at least one release element runs parallel to the hopper wall, at least in sections. The at least one release element is, in particular, rigidly designed. The at least one release element can be smooth and / or profiled on one side facing the hopper wall. This allows the release properties of the at least one release element to be adapted to the hopper wall and / or to the bulk material, especially powdered bulk material. The at least one release element, in particular the respective release element, is connected directly and / or indirectly to the shaft by at least one associated connecting element.In a direct connection, the at least one connecting element is attached directly to the shaft, whereas in an indirect connection, the at least one connecting element is connected to the shaft via at least one other component. The at least one release element primarily serves to detach the bulk material from the hopper wall, while the at least one associated connecting element primarily serves to prevent or break up bulk material bridges. The at least one connecting element runs transversely to the shaft, preferably perpendicular to the shaft.

[0013] The at least one release element and the at least one associated connecting element together form a stirring impeller. The stirring impeller comprises, in particular, at least one release element, preferably exactly one release element, and several associated connecting elements. For a number K of the at least one connecting element associated with the at least one release element, preferably: 1 < K < 6, in particular 2 < K < 5, and in particular 3 < K < 4. Preferably, the stirrer comprises at least two stirring impellers, each formed by at least one release element and at least one associated connecting element.

[0014] An inlet hopper according to claim 4 ensures the simple and reliable feeding of bulk material into a screw conveyor. The at least one release element is, in particular, rigidly designed. To release the bulk material, especially powdered bulk material, from the hopper wall, the at least one release element runs parallel to the hopper wall, at least in sections. A gap is formed between the hopper wall and the at least one release element. The gap dimension should be as small as possible to ensure reliable release of the bulk material from the hopper wall, but at the same time sufficiently large to reliably prevent contact between the at least one release element and the hopper wall, for example, in the case of vibrations. The maximum gap dimension Smax ensures reliable release of the bulk material from the hopper wall.An inlet hopper according to claim 5 ensures the simple and reliable feeding of bulk material into a screw conveyor. The agitator, with its at least one flexible scraper element, enables contact scraping of the hopper wall. This allows the bulk material, particularly powdered bulk material, to be removed from the hopper wall simply and effectively. The at least one flexible scraper element is, for example, designed as an elastic scraper lip and / or as a scraper brush. Preferably, the at least one flexible scraper element is attached to a side of the agitator facing the hopper wall. In particular, the at least one scraper element is attached to an associated release element and / or an associated impeller. The at least one flexible scraper element is preferably mounted in a replaceable manner.This allows at least one flexible scraper element to be replaced when it becomes worn due to contact with the funnel wall.

[0015] An inlet hopper according to claim 6 ensures the simple and reliable feeding of bulk material into a screw conveyor. The agitator extends through the discharge opening in the inlet direction. An end section of the agitator is located outside the hopper's interior. If the inlet hopper is mounted on a housing of the screw conveyor, the end section of the agitator extends into an inlet channel of the housing. The inlet channel connects an inlet opening of the housing to the at least one housing bore formed in the housing for accommodating at least one screw shaft. Because the agitator extends into the inlet channel, a housing wall that laterally delimits the inlet channel can be cleared of bulk material, particularly powdered bulk material. Bulk material that enters the inlet channel from the inlet hopper and adheres to the housing wall can be detached from the housing wall by means of the agitator.In particular, it prevents the inlet channel from being narrowed or blocked by a layer of powder accumulating on the housing wall.

[0016] An inlet hopper according to claim 7 ensures simple and reliable feeding of bulk material into a screw conveyor. The inlet hopper can be used to feed various bulk materials, particularly powdered bulk materials. When changing the bulk material, it may be necessary to clean the hopper wall and the agitator. The at least one cleaning nozzle serves this purpose. The at least one cleaning nozzle is used for dry cleaning and / or wet cleaning. The cleaning fluid can be air and / or water. Preferably, the at least one cleaning nozzle comprises a spray ball and / or a rotary spray nozzle. For a number V of the at least one cleaning nozzle, the following applies in particular: 1 < V < 6, in particular 2 < V < 5, and in particular 3 < V < 4. Preferably, the at least one cleaning nozzle is arranged on a hopper lid and / or the hopper wall.

[0017] An inlet hopper according to claim 8 ensures simple and reliable feeding of bulk material into a screw conveyor. The at least one impeller is attached to the shaft. For a number M of the at least one impeller, the following applies in particular: 1 < M < 8, in particular 2 < M < 4, and in particular 2 < M < 3. Preferably, several impellers are distributed around the shaft at equal angular intervals. The at least two scraper elements serve to scrape the hopper wall by contact. Preferably, the at least two scraper elements are flexible. For example, the at least two scraper elements are made of a flexible plastic material and / or a flexible rubber material. The at least two scraper elements of the respective impeller can be easily and flexibly adapted to the contour of the hopper wall.If, for example, the inlet funnel has several frustoconical sections with different angles, the at least two scraper elements can be adapted in their length and / or orientation to the contour of the funnel wall. For example, a first, upper scraper element with its axis of rotation encloses an angle ou, where in particular: 30° < ai < 60°, in particular 35° < ou < 55°, and in particular 40° < ou < 50°. Similarly, for example, a second, middle scraper element with its axis of rotation encloses an angle 012, where in particular: 5° < 012 < 35°, in particular 10° < 012 < 30°, and in particular 15° < 012 < 25°. A third, lower scraper element forms an angle a.3 with the axis of rotation, where in particular: 0° < 013 < 10°, and in particular: 0° < 013 < 5°. Preferably: a.3 = 0°.The angle 013 allows for a simple extension of the third scraper element into the inlet channel of a screw machine.

[0018] An inlet hopper according to claim 9 ensures simple and reliable feeding of bulk material into a screw conveyor. Because the at least two scraper elements are offset from each other, the bulk material can be lifted from the hopper wall by a first, upper scraper element and carried away by a second, lower scraper element. The same applies to each further scraper element arranged below a scraper element above it. For an offset angle Acp, the following applies in particular: 10° < Acp < 40°, in particular 15° < Acp < 35°, and in particular 20° < Acp < 30°. The respective offset angle lies in a plane perpendicular to the axis of rotation. The respective offset angles Acp between two successive scraper elements can be the same and / or different.

[0019] An inlet hopper according to claim 10 ensures the simple and reliable feeding of bulk material into a screw conveyor. The at least one scraper element serves to scrape the hopper wall by contact. The at least one scraper element is preferably flexible. For example, the at least one scraper element is made of a flexible plastic material and / or a flexible rubber material. The at least one fastening element serves, in particular, to allow the associated scraper element to be replaced without tools. For example, the at least one fastening element is designed as a tongue and groove of a tongue-and-groove connection and / or as a locking element of a locking connection. Preferably, the respective scraper element is attached in a replaceable manner by at least two fastening elements. The at least one scraper element is, in particular, attached to an associated release element and / or an associated agitator impeller.Preferably, the at least one scraper element is attached to a leading side of the associated release element and / or a leading side of the associated impeller, relative to the desired direction of rotation of the agitator. The at least one scraper element is thus attached to a side of the associated release element or impeller facing the hopper wall. This ensures that the flow of bulk material into the screw conveyor is not impeded.

[0020] The invention further aims to provide a screw conveyor-feed hopper arrangement that enables the simple and reliable feeding of bulk material, particularly powdered bulk material, into a screw conveyor. This objective is achieved by a screw conveyor-feed hopper arrangement with the features of claim 11. The advantages of the screw conveyor-feed hopper arrangement according to the invention correspond to the advantages of the feed hopper according to the invention already described. The screw conveyor-feed hopper arrangement can be further developed, in particular, by at least one feature that is described in connection with the feed hopper according to the invention.

[0021] The inlet hopper is attached to the housing of the screw conveyor so that the discharge opening of the inlet hopper leads into the inlet opening of the housing. Preferably, the inlet hopper is attached to the housing such that the discharge opening and the inlet opening have maximum overlap. Preferably, the discharge opening and the inlet opening have an identical shape, for example, a circle or a square. The discharge opening is located downstream of the inlet opening in the conveying direction and serves to discharge the bulk material or the processed bulk material from the at least one bore in the housing.

[0022] The housing of the screw conveyor has, in particular, several housing sections arranged sequentially in a conveying direction and connected to one another. The inlet opening and the associated inlet channel are formed, in particular, in one of the housing sections. Preferably, the screw conveyor is a multi-shaft screw conveyor. The housing of the multi-shaft screw conveyor has at least two intersecting bores. The multi-shaft screw conveyor comprises at least two screw shafts, each arranged in an associated bore. Preferably, the screw conveyor is a co-rotating twin-shaft screw conveyor. The housing of the twin-shaft screw conveyor has two intersecting bores with a figure-eight cross-section.The twin-shaft screw machine comprises two screw shafts which are arranged in the respective housing bore and can be rotated in the same direction.

[0023] The screw machine can be used as a processing screw machine for processing the

[0024] be designed for bulk material, in particular powdered bulk material, or as a feed screw machine for feeding the bulk material, in particular powdered bulk material, into a processing screw machine.

[0025] A screw conveyor feed hopper arrangement according to claim 12 ensures simple and reliable feeding of bulk material into a screw conveyor. The feed channel is laterally bounded by a housing wall. The agitator extends into the feed channel in the feed direction. For this purpose, an end section of the agitator, which is arranged outside the hopper interior, can extend into the feed channel, and / or the hopper wall and the agitator arranged inside the hopper can extend section by section into the feed channel. During rotational operation of the agitator, the bulk material, in particular the powdered bulk material, which adheres to the housing wall and / or the hopper wall in the area of ​​the feed channel, is dislodged. Preferably, the agitator extends into the feed channel with a length LR in the feed direction, wherein the feed channel has a length LE. The length LE is defined by the feed opening and the at least one housing bore.Preferably: 0.2 < LR / LE < 1, in particular 0.4 < LR / LE < 1, and in particular 0.9 < LR LE < 1.

[0026] In the end section, the stirrer can have at least one release element. This release element is preferably rigid. A gap with a maximum gap dimension s is preferably provided between the housing wall and the release element. ma x formed, in particular where: 0.2 mm < s ma x < 15 mm, in particular 0.5 mm < Smax < 10 mm, and in particular 2 mm < s ma x < 5 mm.

[0027] A screw conveyor feed hopper arrangement according to claim 13 ensures simple and reliable feeding of bulk material into a screw conveyor. The at least one degassing opening is arranged upstream and / or downstream of the feed opening, particularly when viewed in a conveying direction. Preferably, the at least one degassing opening is arranged upstream of the feed opening in the conveying direction, enabling reverse degassing. Air, which is fed from the hopper interior through the feed channel into the at least one housing bore along with the bulk material, especially powdered bulk material, can escape from the at least one housing bore via the at least one degassing opening. This allows for a higher throughput of bulk material.

[0028] A screw conveyor feed hopper arrangement according to claim 14 ensures simple and reliable feeding of bulk material into a screw conveyor. Because the housing has a recess in the area of ​​the feed opening, the discharge opening of the feed hopper can be positioned closer to the at least one housing bore when viewed in the feed direction. This shortens the feed channel. The surface area of ​​the housing wall that laterally delimits the feed channel is thus reduced. Due to the reduced surface area, the probability of the bulk material, especially powdered bulk material, adhering to the housing wall and accumulating there as a powder layer decreases. In the area of ​​the housing recess, the wall thickness of the housing, viewed in the feed direction up to the at least one housing bore, is less than in the area outside the housing recess.Preferably, the funnel wall and / or a fastening section formed around the discharge opening is located against the housing in the area of ​​the housing recess.

[0029] The housing has a first wall thickness wi in the area outside the housing recess, viewed in the inlet direction, up to the at least one housing bore. Correspondingly, the housing has a second wall thickness W2 in the area of ​​the housing recess, viewed in the inlet direction, up to the at least one housing bore. For a wall thickness ratio W2 / W1, the following applies in particular: 0.05 < W2 / W1 < 0.7, in particular 0.1 < W2 / W1 < 0.6, and in particular 0.2 < W2 / W1 < 0.5. The inlet channel is thus correspondingly shortened due to the housing recess.

[0030] Furthermore, the invention is based on the objective of creating a method for operating a screw machine feed hopper arrangement that enables a simple and reliable feeding of bulk material, in particular powdered bulk material, into a screw machine.

[0031] This problem is solved by a method with the features of claim 15. The advantages of the method according to the invention correspond to the advantages already described of the inlet funnel according to the invention and the screw machine-inlet funnel arrangement according to the invention.

[0032] The inlet hopper is filled, for example, by means of at least one dosing unit, from a storage container either discontinuously (i.e., intermittently) and / or continuously (i.e., continuously) with bulk material, in particular powdered bulk material. The bulk material flows continuously through the discharge opening into the screw conveyor.

[0033] The bulk material is, in particular, a powdered bulk material. The powdered bulk material has, in particular, a particle size distribution where, for a 90th percentile, the following especially applies: 10 pm < d90 < 10,000 pm, in particular 10 pm < d90 < 1,000 pm, and in particular 10 pm < d90 < 500 pm. The particle size distribution can be determined, for example, by a standard sieve analysis.

[0034] The rotational speed of the stirrer around its axis of rotation is adjustable, in particular by means of the drive. For a rotational speed n of the stirrer around its axis of rotation, the following applies in particular: 10 rpm < n < 200 rpm, in particular 20 rpm < n < 60 rpm, and in particular 30 rpm < n < 50 rpm.

[0035] In particular, rotating the agitator around its axis allows bulk material to be detached from the housing wall that borders the inlet channel. When changing the bulk material, the hopper wall and the agitator can be cleaned using the at least one cleaning nozzle.

[0036] Further features, advantages, and details will become apparent from the description of several exemplary embodiments. These show:

[0037] Fig. 1 shows a schematic and partially cutaway view of a screw machine inlet funnel arrangement according to a first embodiment.

[0038] Fig. 2 is an enlarged view of an inlet funnel of the screw machine inlet funnel arrangement in Fig. 1, Fig. 3 is a top view of the inlet funnel in Fig. 2,

[0039] Fig. 4 shows a schematic and partially cutaway view of a screw machine inlet funnel arrangement according to a second embodiment.

[0040] Fig. 5 is a schematic and partially cutaway view of a screw machine inlet funnel arrangement according to a third embodiment,

[0041] Fig. 6 shows a sectional view through the screw machine inlet funnel arrangement in Fig. 5 along section line VI-VI.

[0042] Fig. 7 shows a perspective view of an inlet funnel of a screw machine inlet funnel arrangement according to a fourth embodiment.

[0043] Fig. 8 shows a sectional view through the inlet funnel in Fig. 7 along section line VIII-VIII and a screw machine of the screw machine-inlet funnel arrangement.

[0044] Fig. 9 shows a side view of a stirring unit of the inlet funnel in Fig. 7.

[0045] Fig. 10 shows a top view of the stirring unit in Fig. 9 from below.

[0046] Fig. 11 shows a partially cut-away detail view of a fastening element for the replaceable fastening of a scraper element of the stirring unit in Fig. 9, and

[0047] Fig. 12 shows a schematic and partially cutaway view of a screw machine inlet funnel arrangement according to a fifth embodiment.

[0048] A first embodiment of the invention is described below with reference to Figures 1 to 3. The screw machine-feed hopper arrangement 1 shown in the figures comprises a multi-shaft screw machine 2 and a feed hopper 3 for feeding powdered bulk material P into the multi-shaft screw machine 2. The multi-shaft screw machine 2 serves as a processing screw machine.

[0049] The multi-shaft screw machine 2 comprises a housing 4 made up of several housing sections 6 arranged one after the other in a conveying direction 5 and connected to each other. A discharge plate 7 is attached to the last housing section 6, which forms a discharge opening 8.

[0050] The multi-shaft screw machine 2 is designed as a co-rotating twin-shaft screw machine. The housing 4 has two parallel and intersecting bores 9, 10, which have a figure-eight cross-section. Two screw shafts 11, 12 are arranged concentrically in the bores 9, 10 and are rotatable about their respective axes of rotation 13, 14. The screw shafts 11, 12 include processing elements (not shown) which may be designed as conveying elements and / or kneading elements.

[0051] To drive the worm shafts 11, 12, the multi-shaft worm machine 2 comprises a drive motor 15 and a branching gearbox 17, between which a coupling 16 is arranged. The worm shafts 11, 12 are driven in the same direction, i.e., in the same directions of rotation, about the axes of rotation 13, 14.

[0052] In the first housing section 6, an inlet channel 19 is formed, which connects an inlet opening 18 with the housing bores 9, 10. The inlet opening 18 and the associated inlet channel 19 have a circular cross-section. The inlet channel 19 is laterally bounded by a housing wall 20 of the housing section 6.

[0053] In the first housing section 6, a degassing opening 21 is also provided. The degassing opening 21 serves to discharge air from the housing bores 9, 10. The degassing opening 21 is arranged upstream of the inlet opening 18 in the conveying direction 5. The inlet hopper 3 serves to feed the powdered bulk material P into the multi-shaft screw machine 2. The inlet hopper 3 comprises a hopper wall 22, which at least partially delimits a hopper interior 23. The hopper wall 22 delimits the hopper interior 23, in particular radially, in an inlet direction 24. The hopper wall 22 is designed such that the hopper interior 23 tapers at least partially in the inlet direction 24. The inlet direction 24 runs, in particular, parallel to the direction of gravity.

[0054] The inlet hopper 3 comprises a hopper lid 25, which is arranged on the hopper wall 22 at a feed side. The hopper lid 25 has three feed openings 26, 27, 28 for feeding the powdered bulk material P into the hopper interior 23. Each feed opening 26, 27, 28 can, for example, be connected to an associated metering unit, so that powdered bulk material P of varying composition can be fed into the hopper interior 23. For a number N of feed openings, the following generally applies: 1 < N < 6, in particular 2 < N < 5, and in particular 2 < N < 3.

[0055] The inlet hopper 3 includes a discharge opening 29 on one discharge side. The discharge opening 29 serves to discharge the powdered bulk material P from the hopper interior 23 and to feed the powdered bulk material P into the multi-shaft screw machine 2. The discharge opening 29 has a circular cross-section. The discharge opening 29 corresponds in shape and diameter to the inlet opening 18. Preferably, the discharge opening 29 has a free cross-sectional area AF, in particular: 10 cm² 2 < AF < 2,500 cm 2 , especially 25 cm 2 < AF < 1,000 cm 2 , and especially 100 cm 2 < AF < 500 cm 2 .

[0056] The inlet hopper 3 comprises a stirring unit 30. The stirring unit 30 includes an agitator 31 and a drive 32. The drive 32 is, for example, an electric drive motor. The drive 32 is attached to the hopper lid 25 outside the hopper interior 23. The agitator 31 is located essentially inside the hopper interior 23 and is connected to the drive 32. The agitator 31 can be rotated about a rotary axis 33 in different directions by means of the drive 32. The rotary axis 33 runs parallel to the inlet direction 24. The rotary axis 33 thus runs vertically parallel to the direction of gravity. The agitator 31 is frame-shaped. The agitator 31 includes a shaft 34 to which a first impeller Ri and a second impeller R2 are attached. The impellers Ri and R2, together with the shaft 34, each form a closed frame.For a number M of agitator blades, the following generally applies: 1 < M < 8, in particular 2 < M < 4, and in particular 2 < M < 3.

[0057] The first impeller Ri and the second impeller R2 are arranged opposite each other to the shaft 34. The impeller Ri and R2 are thus arranged at equal angular intervals around the axis of rotation 33, i.e., at angular intervals of 180°.

[0058] The first impeller Ri comprises a release element Ai, which is connected to the shaft 34 by means of four connecting elements V11, V12, V13, and V14. In cross-section, the release element Ai runs parallel to the hopper wall 22. The connecting elements Vn, V12, V13, and V14 are spaced apart from each other in the inlet direction 24 and run perpendicular to the axis of rotation 33. The release element Ai and the associated connecting elements Vn, V12, V13, and V14 are rod-shaped and, together with the shaft 34, form several frames, each of which defines a free passage area for the powdered bulk material P. The release element Ai serves to detach the powdered bulk material P from the hopper wall 22. In contrast, the connecting elements Vn, V12, V13, and V14 serve to break up any bulk material bridges formed by the powdered bulk material P.

[0059] The second impeller R2 is designed accordingly. The second impeller R2 comprises a release element A2, which is connected to the shaft 34 by means of four connecting elements V21, V22, V23, and V24. In cross-section, the release element A2 runs parallel to the hopper wall 22. The connecting elements V21, V22, V23, and V24 are spaced apart from each other in the inlet direction 24 and run perpendicular to the axis of rotation 33. The release element A2 and the associated connecting elements V21, V22, V23, and V24 are rod-shaped and, together with the shaft 34, form several frames, each of which defines a free passage area for the powdered bulk material P. The release element A2 serves to detach the powdered bulk material P from the hopper wall 22. In contrast, the connecting elements V21, V22, V23 and V24 serve to break up bulk material bridges formed by the powdered bulk material P.

[0060] For a number K of connecting elements assigned to the respective release element Ai or A2, preferably: 1 < K < 6, in particular 2 < K < 5, and in particular 3 < K < 4.

[0061] The release elements Ai, A2 serve to release the powdered bulk material P from the hopper wall 22 without contact. For this purpose, a gap 35 is formed between the hopper wall 22 and the respective release element Ai, A2. The respective release element Ai or A2 can be smooth and / or profiled. The gap 35 has a maximum gap dimension Smax perpendicular to the hopper wall 22, where: 0.2 mm < Smax < 15 mm, in particular 0.5 mm < Smax < 10 mm, and in particular 2 mm < Smax < 5 mm.

[0062] The inlet funnel 3 is attached to the housing 4. The inlet funnel 3 comprises a flange-shaped mounting section 36, which is connected to the funnel wall 22 and surrounds the discharge opening 29. The mounting section 36 is connected to the first housing section 6. The inlet funnel 3 is aligned with the first housing section 6 such that the discharge opening 29 opens into and is flush with the inlet opening 18.

[0063] The agitator 31 extends in the inlet direction 24 through the discharge opening 29 and is arranged with an end section E outside the hopper interior 23. The end section E extends through the inlet opening 18 into the inlet channel 19 and terminates in the inlet direction 24 before the housing bores 9, 10. The end section E serves to detach the powdered bulk material P from the housing wall 20 without contact. For this purpose, a gap 37 is formed between the housing wall 20 and the detachment elements Ai, A2. The gap 37 has a maximum gap dimension s ma x. For the maximum gap dimension s ma In particular, x holds true if: 0.2 mm < Smax < 15 mm, especially 0.5 mm < s max < 10 mm, and in particular 2 mm < Smax < 5 mm. The end section E of the agitator 31, which extends into the inlet channel 19, has a length LR in the inlet direction 24. The inlet channel 19 has a length LE in the inlet direction 24. In particular, 0.2 < LR / LE < 1, in particular 0.4 < LR / LE < 1, and in particular 0.9 < LR / L E < 1.

[0064] The inlet funnel 3 comprises three cleaning nozzles 38, 39, 40. The cleaning nozzles 38, 39, 40 are attached to the funnel lid 25. The cleaning nozzles 38, 39, 40 serve to clean the funnel wall 22 and the agitator 31 using a cleaning fluid F. The cleaning nozzles 38, 39, 40 are designed, for example, as spray balls and / or rotary spray nozzles. The cleaning fluid F can be air and / or water. For a number V of cleaning nozzles, the following generally applies: 1 < V < 6, in particular 2 < V < 5, and in particular 3 < V < 4.

[0065] The following describes the operation of the screw machine inlet funnel arrangement 1:

[0066] The inlet hopper 3 is continuously and / or discontinuously filled with powdered bulk material P through the feed openings 26, 27, 28. The powdered bulk material P has a particle size distribution, where, for a 90th percentile, in particular: 10 pm < d90 < 10,000 pm, in particular 10 pm < d90 < 1,000 pm, and in particular 10 pm < d90 < 500 pm.

[0067] The powdered bulk material P located in the hopper interior 23 tends, on the one hand, to adhere to the hopper wall 22 and form a powder layer, and on the other hand, to form bulk material bridges in the hopper interior 23. To prevent this, the agitator 31 is driven by the drive 32 about the axis of rotation 33. For a rotational speed n of the agitator, the following applies in particular: 10 rpm < n < 200 rpm, especially 20 rpm < n < 60 rpm, and especially 30 rpm < n < 50 rpm.

[0068] Because the agitator 31 extends into the inlet channel 19 with its end section E, the release elements Ai, A2 also detach the powdered bulk material P from the housing wall 20. The powdered bulk material P flows out of the hopper interior 23 through the discharge opening 29 in the inlet direction 24. The discharged powdered bulk material P enters the inlet channel 19 through the inlet opening 18 and from there reaches the housing bores 9, 10. In the housing bores 9, 10, the powdered bulk material P is conveyed in the usual manner in the conveying direction 5 by means of the screw shafts 11, 12. Air that enters the housing bores 9, 10 together with the powdered bulk material P from the hopper interior 23 can escape via the degassing opening 21. The powdered bulk material P can thus be fed easily and reliably into the multi-shaft screw machine 2.

[0069] For cleaning, a cleaning fluid F can be sprayed into the hopper interior 23 using the cleaning nozzles 38, 39, 40. The cleaning fluid F is air for dry cleaning and water for wet cleaning. The hopper wall 22 and the agitator 31 are cleaned using the cleaning fluid F.

[0070] A second embodiment of the invention is described below with reference to Fig. 4. In contrast to the first embodiment, the first housing section 6 has a housing recess 41. The housing recess 41 is formed around the inlet opening 18. As a result, the inlet channel 19 is shortened in the inlet direction 24 compared to the first embodiment.

[0071] The first housing section 6 has a first wall thickness wi in the area outside the housing recess 41, viewed in the inlet direction 24, up to the housing bores 9, 10. Correspondingly, the first housing section 6 has a second wall thickness W2 in the area of ​​the housing recess 41, viewed in the inlet direction 24, up to the housing bores 9, 10. Due to the housing recess 41, the second wall thickness W2 is less than the first wall thickness wi. In particular, 0.05 < W2 / W1 < 0.7, more specifically 0.1 < W2 / W1 < 0.6, and more specifically 0.2 < W2 / W1 < 0.5. The inlet channel 19 and the housing wall 20 are thus correspondingly shortened in the inlet direction 24. The fastening section 36 is attached to the first housing section 6 in the area of ​​the housing recess 41. The shortening reduces the probability that the powdered bulk material P will adhere to the housing wall 20.

[0072] The agitator 31 further comprises scraper elements Bi and B2 for contacting and scraping the hopper wall 22. The scraper elements Bi and B2 are flexible, for example, as a scraper lip and / or a scraper brush. The scraper element Bi is replaceably attached to the release element Ai. Similarly, the scraper element B2 is replaceably attached to the release element A2. When the agitator 31 rotates about the axis of rotation 33, the scraper elements Bi and B2 contact the hopper wall 22 and clean it of the powdered bulk material P. The scraper elements Bi and B2 also extend into the inlet channel 19 and contact the housing wall 20. For further details regarding the design and operation, reference is made to the preceding embodiment.

[0073] A third embodiment of the invention is described below with reference to Figures 5 and 6. In contrast to the previous embodiments, the stirring unit 30 is arranged such that the axis of rotation 33 is perpendicular to the inlet direction 24. The axis of rotation 33 is therefore horizontal to the direction of gravity. The drive 32 is attached to the hopper wall 22. The hopper wall 22 is U-shaped in the cross-section shown in Figure 6 with respect to the axis of rotation 33. The first housing section 6 has a housing recess 41 around the inlet opening 18, so that the mounting section 36 is attached to the housing section 6 in the area of ​​the housing recess 41. The inlet channel 19 is thereby shortened. The scraper element Bi is replaceably attached to the release element Ai and the connecting elements Vn and V14, so that the U-shaped section and the end faces of the hopper wall 22 are scraped in contact.Accordingly, the scraper element B2 is interchangeably attached to the release element A2 and the connecting elements V21 and V24. The connecting elements V12 and V13, as well as the connecting elements V22 and V23, serve to break up any bulk material bridges. In Fig. 6, the agitator 31 is shown in a first position parallel to the inlet direction 24 and in a second position at an angle to the inlet direction 24. The multi-shaft screw machine 2 is designed as a feed screw machine for feeding the powdered bulk material P into a processing screw machine. The housing 4 has no discharge plate. The discharge opening 8 is formed in the last housing section 6. The screw shafts 11, 12 extend through the discharge opening 8. For further details regarding the construction and operation, reference is made to the description of the preceding exemplary embodiments.

[0074] A fourth embodiment of the invention is described below with reference to Figures 7 to 11. In contrast to the preceding embodiments, the stirring unit 30 comprises a stirrer 31 with a first stirring blade Ri, a second stirring blade R2, and a third stirring blade R3. The stirring blades Ri, R2, and R3 are arranged at equal angular intervals around the axis of rotation 33 and are attached to the shaft 34. The stirring blades Ri, R2, and R3 are thus arranged at angular intervals of 120° to each other. Each of the stirring blades Ri, R2, and R3, together with the shaft 34, forms a closed frame.

[0075] The first impeller Ri comprises the release element Ai, which is connected to the shaft 34 by means of three connecting elements V11, V12 and V13. Similarly, the second impeller R2 comprises the release element A2 and the connecting elements V21, V22 and V23, and the third impeller R3 comprises the release element A3 and the connecting elements V31, V32, V33.

[0076] The funnel wall 22 extends in three annular sections with respect to the axis of rotation 33, becoming progressively steeper. The axis of rotation 33 is vertically oriented. The separation elements Ai, A2, and A3 extend essentially parallel to the funnel wall 22 and each form three sections. The first separation element Ai forms sections a2i, a22, and a23. Similarly, the second separation element A2 forms sections a2i, a22, and a23, and the third separation element A3 forms sections a3i, a32, and a33. Sections a2i, a2i, and a3i form an angle ou with the axis of rotation 33, where in particular: 30° < ou < 60°, in particular 35° < ai < 55°, and in particular 40° < ou < 50°. The sections an, a22 and a32 enclose an angle 012 with the axis of rotation 33, where in particular: 5° < 012 < 35°, in particular 10° < 012 < 30°, and in particular 15° < 012 < 25°.Furthermore, sections a23 and a33 form an angle 013 with the axis of rotation 33, where in particular: 0° < 00 < 10°, and especially 0° < a3 < 5°. A corresponding flexible wiper element is interchangeably attached to each of the sections a33 and a33. The flexible wiper elements are designated Bn to B33, corresponding to the sections a33 and a33. The flexible wiper elements Bn, B21, and B31 are thus inclined at an angle of 0° relative to the axis of rotation 33. Similarly, the flexible wiper elements Bn, B22, and B32 are arranged at an angle of 012 relative to the axis of rotation 33, and the flexible wiper elements B13, B23, and B33 are arranged at an angle of 0° relative to the axis of rotation 33. The flexible wiper elements Bn to B33 are, for example, made of a flexible plastic material and / or a flexible rubber material.

[0077] The scraper elements Bn and B12 of the first impeller Ri are arranged at an angle to each other on the release element Ai. The scraper elements Bn and B12 enclose an offset angle Acpi between corresponding ends. Similarly, the scraper elements B12 and B13 are arranged at an angle to each other on the release element Ai. The scraper elements B12 and B13 enclose an offset angle A(p2) between corresponding ends. The offset angles Acpi and Acp2 lie in a plane perpendicular to the axis of rotation 33. The offset angles Acpi and Acp2 can be the same or different. Preferably, the offset angles are between 10° and 40°, particularly between 15° and 35°, and especially between 20° and 30°. Similarly, the scraper elements B21 and B22, as well as the scraper elements B31 and B32, enclose an offset angle Acpi.Furthermore, the scraper elements B22 and B23, as well as the scraper elements B32 and B33, incorporate an offset angle Acp2. The respective offset angles Acpi and Acp2 are oriented opposite to the intended direction of rotation of the agitator 31. This allows bulk material P, which, for example, has been removed from the hopper wall 22 by the scraper element Bn, to be carried along by the scraper element B12 below it. Similarly, bulk material P, which, for example, has been removed from the hopper wall 22 by the scraper element B12, can be carried along by the scraper element B13 below it. This applies accordingly to the agitator blades R2 and R3.

[0078] The wiper elements Bn to B33 are arranged on a leading side of their respective release elements Ai to A3 with respect to a specified direction of rotation. The wiper elements Bn to B33 are interchangeably attached to their respective release elements Ai to A3 by means of fastening elements 42. The fastening elements 42 are designed as locking elements in the form of headed bolts. Each wiper element Bn to B33 is secured against rotation by means of two associated fastening elements 42. The fastening elements 42 comprise a pin 43 and an associated head 44. The respective pin 43 is attached to the respective release element Ai to A3 such that a gap is formed between the head 44 and the respective release element Ai to A3. The gap has a width corresponding to the thickness of the wiper element Bn to B33 being attached.Each wiper element Bn to B33 has through-openings 45, allowing the head 44 to be guided through the corresponding through-opening 45 of the flexible wiper element Bn to B33, and the wiper element Bn to B33 to lock into place in the resulting gap. This is illustrated in Figure 11 using wiper element B13 as an example. The fastening elements 42 thus enable the wiper elements Bn to B33 to be replaced easily and quickly without the use of tools.

[0079] Regarding the further structure and functionality, reference is made to the explanations of the preceding exemplary embodiments.

[0080] A fifth embodiment of the invention is described below with reference to Figure 12. In contrast to the preceding embodiments, the funnel wall 22 extends through the inlet opening 18 into the inlet channel 19 and rests against the housing wall 20. The agitator 31 is arranged in the interior of the funnel 23, but extends together with the funnel wall 22 through the inlet opening 18 into the inlet channel 19. Thus, it is not the housing wall 20 that is cleaned by the agitator 31 in the inlet channel 19, but rather the funnel wall 22, which extends into the inlet channel 19 up to the housing bores 9, 10. For further details regarding the construction and operation, reference is made to the description of the preceding embodiments.

[0081] The individual features of the exemplary embodiments can be combined in any way.

Claims

- 23 - Patent claims 1. Inlet hopper for feeding bulk material into a screw conveyor, comprising - a funnel wall (22), - a funnel interior (23), — which is at least partially bounded by the funnel wall (22), — which tapers at least in sections in an inlet direction (24), - at least one feed opening (26, 27, 28) for feeding bulk material (P) into the hopper interior (23), - a discharge opening (29) for discharging the bulk material (P) from the hopper interior (23) and for feeding the bulk material (P) into a screw conveyor (2), and - a stirring unit (30) with — a stirrer (31) arranged at least partially in the interior of the funnel (23) and a drive (32) for rotating the stirrer (31) about a rotational axis (33), characterized in that the stirrer (31) is designed in a frame-like manner for detaching the bulk material (P) from the funnel wall (22) and for breaking up bulk material bridges of the bulk material (P).

2. Inlet funnel according to claim 1, characterized in that the stirrer (31) comprises a shaft (34) and at least one stirring vane (Ri, R2; Ri, R2, R3) which is attached to the shaft (34).

3. Inlet funnel according to claim 1 or 2, characterized in that the stirrer (31) comprises a shaft (34) and at least one release element (Ai, A2; Ai, A2, A3) for releasing the bulk material (P) from the funnel wall (22), which is connected to the shaft (34) by at least one connecting element (Vn, V12, V13, V14, V21, V22, V23, V24; Vn, V12, V13, V21, V22, V23, V31, V32, V33).

4. Inlet funnel according to claim 3, characterized in that that a gap (35) with a maximum gap dimension Smax is formed between the funnel wall (22) and the at least one release element (Ai, A2; Ai, A2, A3), wherein: 0.2 mm < Smax < 15 mm, in particular 0.5 mm < Smax < 10 mm, and in particular 2 mm < Smax < 5 mm.

5. Inlet funnel according to at least one of the preceding claims, characterized in that the stirrer (31) comprises at least one flexible scraper element (Bi, B2; Bn to B33) for contacting and scraping the funnel wall (22).

6. Inlet funnel according to at least one of the preceding claims, characterized in that the stirrer (31) extends through the discharge opening (29) to outside the funnel interior (23).

7. Inlet funnel according to at least one of the preceding claims, characterized by at least one cleaning nozzle (38, 39, 40) for cleaning the funnel wall (22) and the stirrer (31) by means of a cleaning fluid (F).

8. Inlet funnel according to at least one of the preceding claims, characterized in that the stirrer (31) comprises at least one stirring vane (Ri, R2, R3) and at least two scraper elements (Bn to B33) are attached to each stirring vane (Ri, R2, R3).

9. Inlet funnel according to claim 8, characterized in that the at least two scraper elements (Bn to B33) of each agitator blade (Ri, R2, R3) have an offset angle (Acpi, Acp2) to each other.

10. Inlet funnel according to at least one of the preceding claims, characterized in that the stirrer (31) comprises at least one scraper element (Bn to B33) and at least one associated fastening element (42) for interchangeable fastening.

11. Screw conveyor inlet funnel arrangement, comprising - a screw machine (2) with — a housing (4), — at least one housing bore (9, 10) formed in the housing (4), — at least one worm shaft (11, 12) arranged in the respective housing bore (9, 10), — an inlet opening (18) formed in the housing (4) and an associated inlet channel (19) for connecting the inlet opening (18) to the at least one housing bore (9, 10), — a discharge opening (8), and - an inlet funnel (3) according to at least one of the preceding claims, wherein — the inlet funnel (3) is attached to the housing (4) and — the drainage opening (29) opens into the inlet opening (18).

12. Screw machine inlet funnel arrangement according to claim 11, characterized in that the agitator (31) for detaching the bulk material (P) extends into the inlet channel (19).

13. Screw machine inlet funnel arrangement according to claim 11 or 12, characterized in that the housing (4) comprises at least one degassing opening (21) for removing air from the funnel interior (23).

14. Screw machine inlet funnel arrangement according to at least one of the claims 11 to 13, characterized in that the housing (4) has a housing recess (41) in the area of ​​the inlet opening (18) to shorten the length of the inlet channel (19).

15. Method for operating a screw machine inlet funnel arrangement, comprising the following steps: - Providing a screw conveyor feed hopper arrangement (1) according to at least one of claims 11 to 14, - Feeding bulk material (P) through the at least one feed opening (26, 27, 28) into the hopper interior (23), - Rotating the stirrer (31) about the axis of rotation (33) by means of the drive (32) to detach the bulk material (P) from the hopper wall (22) and to break up bulk material bridges of the bulk material (P), and - Discharging the bulk material (P) from the hopper interior (23) through the discharge opening (29) and feeding the bulk material (P) into the screw machine (2) through the inlet opening (18).

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