Patent Application
20100078511
The subject of the invention is a star feeder for conveying all types of bulk materials and having a comminuting insert, according to the preamble to patent claim 1.
In star feeders, the problem exists that partially large-volume agglomerates are fed in at the inlet connection and, because of their volume, cannot be introduced into the star wheel chamber. The prior art here provides star feeders having so-called shredding inserts, which are generally installed in the inlet connection on the inlet side in the star wheel housing.
The agglomerates which are fed in there are pressed by the star wheel motion into the cutting blade which is disposed in the inlet connection and protrudes there, or into the cutting inserts which are disposed there, and are there comminuted.
A drawback of known comminution methods is, however, that with increasing operating time, particularly in the use of detachable cutting inserts, the fastening thereof works loose and has to be readjusted. In an extreme case, it can happen that the fastening comes loose during operation and the cutting blade falls into the star wheel chamber, resulting in the destruction of the star feeder.
In the case of other known cutting inserts, the drawback exists that the cutting edges become worn and wear down, whereby, on the one hand, metal particles are undesirably carried into the conveyed material and, on the other hand, these cutting inserts must from time to time be exchanged.
The object of the invention is therefore to refine a star feeder with comminuting insert of the type stated in the introduction such that, without the use of static blades, wear-exposed cutting edges or the like are avoided and a longer operating time with operationally reliable working method is obtained.
For the achievement of the defined object, the invention is characterized by the technical teaching of claim 1.
A fundamental feature of the invention is that in the inlet region of the star feeder there is disposed a comminuting insert, which is configured in the running direction of the star wheel as a shearing wall, which forms at least two mutually angled shearing surfaces, which widen conically to the inlet direction of the feed-in material upward in the feed-in direction and meet or merge roughly centrally in the region of a contour, the longitudinal extent of the contour extending in a conically widening manner in the feed-in direction.
According to the invention, the contour can be configured as a straight or curved edge, in particular as a feed edge. The contour can also, however, be configured with little definition as a rounded transition between two shearing surfaces. According to the invention, the shearing surfaces can be plane surfaces, curved surfaces or 3-dimensionally shaped surfaces, for example corrugated surfaces.
A fundamental feature of the present invention is hence that cutting inserts and wear-exposed cutting edges are dispensed with and that a fixed shearing wall, which directly forms an integral component of the feed-in connection, is integrated into the comminuting insert at the inlet of the star feeder. Thus the advantage exists that no detachable and wear-exposed cutting inserts are any longer present and that, consequently, corresponding (operationally vulnerable) fastenings are also absent.
It can here be provided that the shearing wall is doubled onto the inside of the inlet surfaces of the comminuting insert and this doubling consists of a particularly wear-resistant material.
Normally, however, this is not necessary, so that the shearing wall is part of the housing wall of the comminuting insert.
The shearing wall according to the invention, with the shearing surfaces which are disposed there, is thus an integral housing component of the exchangeable comminuting insert.
The shredder according to the invention differs substantially from same-acting devices according to the prior art through the use of a roughly cylindrical shredding connection. The shredding connection is inserted flush into the housing inlet. The inner contour is matched to the star wheel. The shredding connection is exchangeable. Due to the design, a readjustment or exchange of static blades is unnecessary. Damage to the star feeder, due to a loosening of the screws on the cutting device, is thus precluded. Inside the star feeder there are no longer any detachable parts present. As a result of the solid construction of the shredding connection, an extremely long running time is possible, which cannot be guaranteed with static blades. The shredding connection boasts a special geometric shape, which allows an ideal cutting process. The cutting (or crushing or breaking) of the agglomerates is possible in both rotational directions. All structural parts which are placed under load have been checked by means of FEM calculation with respect to the maximally permitted torque. Furthermore, the drive unit and the star wheel have been correspondingly strengthened.
The invention is not limited to the fact that the shearing wall in the comminuting insert consists of just two shearing surfaces, which stand conically at an angle to each other and meet or merge centrally in a contour beveled roughly conically to the vertical.
In a refinement of the present invention, it is provided that, instead of two such shearing surfaces, a multiplicity of further shearing surfaces are present, which are disposed, so to speak, lying prismatically one beside the other, and that respectively two mutually adjacent prismatic surfaces meet or merge in a contour, so that there are a plurality of contours, combined with a plurality of meeting shearing surfaces.
Hence it is important in the current invention that the longitudinal extent of the contour juts conically into the inlet region of the star wheel and widens conically in the upward direction, so that this angular contour acts as a feed hopper.
It is additionally important that said shearing wall is located in the region of a bottom surface of the comminuting insert, this bottom surface reducing the inlet cross section of the feed hopper of the star feeder. The advantage thus exists that the cutting edges for the shearing wall can be disposed in the region of this bottom surface, whereby an improved sealing surface against leakage losses is ensured.
The shearing edges or shearing contours of the shearing wall are drawn into, so to speak, the inlet region of the star feeder in order thus to form a bottom surface of enlarged area, which forms a sealing surface for protection against leakage losses upon passage of the star wheel web. The term shearing edge should not be interpreted restrictively as a sharp edge, but rather, according to the invention, includes straight or curved running contours, as well as connecting contours of mutually merging surfaces.
Hence it is important in the present invention that the large-volume agglomerates, which, due to their size, protrude from the star wheel chamber, are forced by the passing star wheel web against the shearing surfaces disposed at an angle to one another and are centered there particularly with respect to the contour joining the two shearing surfaces.
Since this contour forms an angle in the inlet direction (widening conically in the upward direction), the agglomerate to be comminuted is directed by the two shearing surfaces in the direction of the middle contour, is crushed there against the wall and the remnants are diverted upward in the opposite direction to the feed-in direction and fall into the succeeding star wheel chamber.
In principle, a crusher action therefore takes place and no cutting action, as was known in the prior art.
As a result of this crusher action acting on the agglomerates to be comminuted, large areal portions in the region of the shearing wall are therefore in use, which is associated with the advantage that only a small amount of wear is incurred there, the abrasion of metallic chips cannot normally take place and, moreover, detachable parts are no longer present in this region.
Depending on the size of the agglomerate, this process can also be multiply repeated, to be precise until such time as the agglomerate is broken into such small pieces that it can be taken up by the following star wheel chamber.
The subject of the present invention derives not only from the subject matter of the individual patent claims, but also from the intercombination of the individual patent claims.
All data and features disclosed in the documentation, inclusive of the abstract, particularly the spatial configuration represented in the drawings, are claimed as fundamental to the invention, insofar as, individually or in combination, they are novel relative to the prior art.
The invention is explained in greater detail below with reference to drawings representing just one embodiment. Further features and advantages of the invention here emerge from the drawings and their description, wherein:
In
In the housing 2, a rotary star wheel shaft 6 is received by roller bearings 7, the star wheel shaft 6 being connected in a rotationally secure manner to a star wheel 5.
The star wheel 5 forms a multiplicity of evenly distributed star wheel chambers, each star wheel chamber being divided off from the adjacent star wheel chamber by a star wheel web 12, 12a, 12b, 12c.
The rotary drive for the star wheel shaft 6 is realized via a flat gear 8, which is driven by a drive motor 9.
The torque of the drive motor 9 must be chosen such that a high torque can be exerted on the star wheel 5 in order to apply the aforementioned crusher action to the bulk material agglomerates 29 running in the inlet direction (arrow direction 11) into a comminuting insert 10 in the arrow direction 11. In
According to
According to
Now it is important that, according to the invention, a shearing wall 20 is present in the comminuting insert 10, which shearing wall consists of two mutually angled shearing surfaces 21, 22. Each shearing surface 21, 22 is preferably spherically curved. The invention is not, however, limited thereto. It can also be provided that the respective shearing surface 21, 22 is configured with an exactly straight surface, the two shearing surfaces 21, 22 meeting centrally in a contour, hereinafter denoted as the feed edge 23.
In order to arrange these shearing surfaces 21, 22 such that they are inclined at the cone angle to the feed-in direction (arrow direction 11), these are disposed in the region of bottom surfaces 18, 19 on the bottom side of the comminuting insert 10.
A larger bottom surface 19 is therefore present, which reduces the clear width of the inlet region and in the region of which, as the bottom edge, are disposed the shearing edges 24, 25 as the lower limit of the respective shearing surfaces 21, 22.
A smaller bottom surface 19 is also present, which is configured at an angle to the larger bottom surface 18. By virtue of the fact that the shearing edges 24, 25 are disposed in the region of a larger bottom surface 18, which bottom surface lies on the star wheel diameter 27, a large-area sealing surface is obtained there, which helps prevent leakage air losses. Leakage losses are thereby minimized.
Since the comminuting insert 10 preferably consists of a cast-iron material, it is preferred that, for weight-saving reasons, a multiplicity of cutouts 26 in the cylinder body, as is represented in
These cutouts 26 form no functional impairment whatsoever, since they breach only the cylinder casing, but are closed off to the fore (on the inlet side) by corresponding opposing surfaces. This applies, in particular, to the cone wall 28 lying opposite the shearing wall 20 in the running direction 15, which cone wall is also part of the comminuting insert 10.
Such a cone wall 28, which is directed conically inward in the running direction, has the advantage, namely, that when the star wheel 5 is driven in the opposite direction to the rotational direction 15, a crusher action takes place also in the region of this cone wall 28.
It is here important, moreover, that the longitudinal extent of the feed edge 23 forms an edge angle 34 which is inclined by roughly 20° toward the vertical.
This means that the feed edge 23 extends in a conically widening manner outward from the comminuting insert 10.
The same applies to the shearing surfaces 21, 22, which extend likewise in a conically widening manner outward in the opposite direction to the arrow direction 11.
The shearing surfaces 21, 22 thus form, in conjunction with the feed edge 23, corresponding funnel-shaped inlet surfaces.
It should here also be added that the cone wall 28 has an inlet edge 30, the longitudinal extent of which likewise widens conically in the outward direction.
Since the two shearing surfaces 21, 22 are configured as cone surfaces on a circumferential cylinder casing, in the upper end region thereof an arc-shaped surface contour 31 is formed, as can be seen from
The feed edge 23 converges on the bottom side at a junction point 32, and the crusher action on the bulk material agglomerates to be comminuted is now explained in greater detail with reference to
The arrow direction 33 illustrates that all bulk material agglomerates 29 are centered in the arrow direction 33 upon this central feed edge 23 due to the angular setting of the two shearing surfaces 21, 22 and are there broken up.
The upper part of the broken-off the bulk material agglomerate 29 is diverted in the arrow direction 35 upward along the feed edge 23 and then falls into the succeeding further star wheel chamber, which is limited in the upward direction by the following star wheel web. The lower part of the comminuted bulk material agglomerate 29 is received, however, into the same star wheel chamber as is represented in
The above-stated description reveals that a superior crusher action for the bulk material agglomerate 29 to be comminuted is obtained, without the need to use cutting edges, shredding blades or barb-like projections or the like. It is therefore more a case of a crusher action on the bulk material agglomerate than a cutting action.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 049 356.2 | Sep 2008 | DE | national |
