Patent Application
20130337727
1. Technical Field
The invention relates to an impeller for feeding blasting abrasive to be accelerated into the centrifugal wheel of a blasting installation, said impeller being arrangeable in the central region of the centrifugal wheel within a distributing sleeve having a distributing opening, and said impeller having, on at least one lateral disk, guiding members for guiding the blasting abrasive toward the outside, wherein the guiding members each have two lateral surfaces which form, with lateral surfaces of adjacent guiding members, channels through which the blasting abrasive is dischargeable toward the outside. The invention also relates to a blasting installation having a centrifugal wheel, said blasting installation having such an impeller.
2. Prior Art
Blasting installations equipped with centrifugal wheels are used for example to free surfaces of metal rolled products from scale and/or rust before the surface receives a protective coating, in that a blasting abrasive generally comprising fine metal particles is hurled against the surface. In such a blasting installation, all of the particles of the blasting abrasive should preferably move toward the outside tangentially and as parallel as possible to the blades of the rotating centrifugal wheel. However, this is frequently not the case. A considerable number of these particles strike the lateral disks and the blades and rebound therefrom, in a manner comparable to a ping-pong ball. This not only has a negative effect on the exit speed of the blasting abrasive from the centrifugal wheel, but also results in a non-uniform distribution of the blasting abrasive on the surface to be cleaned. As a result of the blasting abrasive particles impacting against the parts of the centrifugal wheel, the latter is also subjected to a high degree of wear.
In order to improve the blasting abrasive distribution and also to reduce the wear on the centrifugal wheel, it is known to arrange what is known as an impeller in the center of such a centrifugal wheel. Such an impeller is also subjected to a high degree of wear. As a rule, it sits in a distributing sleeve which surrounds it coaxially and has a distributing or discharging opening. During operation of the blasting installation, blasting abrasive is guided in the axial direction into the center of the impeller. The impeller is set into rapid rotation and guides the blasting abrasive radially toward the outside along the impeller channels formed by adjacent guiding members. In the space between the distributing sleeve and the impeller, the blasting abrasive enters a virtually circular path and circulates in this region along this circular path. On account of the rotation of the impeller, the blasting abrasive is finally transferred as tangentially as possible from the distributing opening in the distributing sleeve into the operative region of the blades of the centrifugal wheel. This results in a soft transition of the blasting abrasive into the blade region of the centrifugal wheel over the entire width, with subsequent uniform acceleration as far as the exit from the blade. The blasting abrasive is substantially prevented from striking the blades and side walls of the centrifugal wheel.
It is the object of the invention to optimize such an impeller, in particular with regard to its service life.
This object is achieved by an impeller for feeding blasting abrasive to be accelerated into the centrifugal wheel of a blasting installation, said impeller being arrangeable in the central region of the centrifugal wheel within a distributing sleeve having a discharging opening, and said impeller having, on at least one lateral disk, guiding members for guiding the blasting abrasive toward the outside, wherein the guiding members each have two lateral surfaces which form, with lateral surfaces of adjacent guiding members, channels through which the blasting abrasive is dischargeable toward the outside, characterized in that one or each guiding member has in each case a top side which connects the outer ends of the two lateral surfaces of the guiding member together, and which has at least one section which is arranged in or above an imaginary non-curved reference plane that connects the lateral surfaces of the guiding member together likewise at their outer ends.
Correspondingly, one or each guiding member of an impeller according to the invention has in each case a top side which is directed radially toward the outside and connects the outer ends of the two lateral surfaces of the guiding member together, and which has at least one section which is arranged either within or above an imaginary non-curved reference plane that connects the mentioned (channel-delimiting) lateral surfaces of the guiding member together likewise at the outer ends.
According to the abovementioned first alternative of the invention, a top-side section, arranged above the imaginary reference plane, accordingly projects radially outwardly beyond the reference plane. In the second alternative according to the invention, this section is located precisely within the imaginary reference plane.
Both embodiments result in a particular shape of the space between the top side of the respective guiding member and that section of the distributing sleeve surrounding the impeller that is opposite the top side.
Tests by the applicant have shown that such a structural shape of the guiding members of the impeller results, during operation of the blasting installation, in particularly low wear of the impeller and also of the centrifugal wheel, in the center of which the impeller sits in the state installed in the blasting installation. In addition, the blasting abrasive distribution and the blasting pattern of the blasting installation is particularly uniform.
Generally, according to the invention, all of the top-side sections or top-side regions that form the top side are arranged in and/or above the imaginary reference line. Accordingly, according to the invention, in one variant all of the sections or regions of the top side can be arranged above the reference plane. In another variant, all of the sections of the top side may be located in the reference plane. In a third variant, finally, at least one section of the top side may be located in the reference plane and at the same time at least one section of the top side may be located above the reference plane.
As far as the at least one section of the top side that is arranged above the reference plane is concerned, said top side can in general extend in a curved or non-curved manner or in an inclined or non-inclined manner with respect to the reference plane.
Preferably, the guiding member is formed symmetrically to an in particular axially extending longitudinal center plane of the guiding member. In addition, each guiding member is in this case preferably arranged on the impeller such that the respective longitudinal center planes each extend substantially radially.
In a preferred embodiment of the invention, the top side of the guiding member has, on both sides of the longitudinal center plane, in each case at least one section arranged above the reference plane, said section extending in an inclined manner with respect to the imaginary reference plane. Each of the two sections in this case extends in each case in an inclined manner with respect to the imaginary reference plane such that the respective section has a positive inclination, in each case as viewed from the lateral surface adjacent to the respective section in the direction of the longitudinal center plane and with respect to the reference plane. In other words, the height of the respective section increases with respect to the reference plane in each case in the event of notional progression in the direction of the longitudinal center plane. Preferably, each of these two sections also directly adjoins that lateral surface of the guiding member that is adjacent to it.
The abovementioned two inclined sections of the surface that extend on both sides of the longitudinal center plane may be connected together directly or by at least one connecting section, extending at least regionally in a curved manner, of the top side.
In a further embodiment of the invention, on both sides of the longitudinal center plane there is located in each case at least one non-curved top-side section that adjoins in particular the respective lateral surface and is arranged within the imaginary reference plane. In this case, these two sections naturally extend in this embodiment in non-inclined manner with respect to the reference plane.
These top-side sections that extend within the reference plane are also preferably connected together by a connecting section.
In a further configuration of this embodiment, the connecting section preferably has connecting part-sections that in each case adjoin the respective top-side section and extend in each case perpendicularly or approximately perpendicularly thereto and are arranged above the reference plane, and also a connecting part-section that connects the abovementioned perpendicular connecting part-sections together, and extends in a manner parallel or approximately parallel to the top-side sections and likewise above the reference plane.
As far as the abovementioned opposite lateral surfaces of adjacent guiding members are concerned, said lateral surfaces laterally delimiting the channels between the guiding members, these lateral surfaces preferably extend in a manner parallel or approximately parallel to one another and spaced apart from one another.
As far as the guide members themselves are concerned, these may be, inter alia, in the form of a solid block or for example be constructed from individual profiled pieces or profiled strips. Different variants are conceivable here.
Further features of the invention can be gathered from the appended claims, the following description of a preferred exemplary embodiment and the appended drawing, in which:
The impeller 10 sits, together with the sleeve 12 surrounding it, in the center of a centrifugal wheel (not illustrated) of the blasting installation. The structure of such a blasting installation is known in principle from the prior art. A centrifugal wheel inserted into such a blasting installation and driven by a motor has a plurality of centrifugal wheel blades, arranged in a manner distributed in the circumferential direction along a lateral disk, for accelerating the blasting abrasive. First of all, the blasting abrasive to be accelerated is supplied to the impeller 10 through a feed line (not illustrated). More precisely, the blasting abrasive is directed out of a blasting abrasive source or a blasting abrasive reservoir into the center 14 of the impeller. During operation of the blasting installation, the impeller 10 is set into rotation about the rotational axis 16 via a drive (not illustrated). The blasting abrasive supplied centrally thereto is guided along channels 18 toward the outside by the impeller 10. The channels 18 are in this case formed by pairs of lateral surfaces 26a, 26b of adjacent guiding members 20a, first embodiment, or 20b, second embodiment.
Through the channels 18, blasting abrasive passes from radially further in to radially further out and is accelerated in the direction of rotation of the impeller 10 on a circular path between the guiding members 20a or 20b and the sleeve 12. Via the discharging opening 22 in the sleeve 12, the blasting abrasive is finally output into the angular region of the blades of the centrifugal wheel (not illustrated). Here, the blasting abrasive exits substantially tangentially from the discharging opening 22. This results in a soft transition of the blasting abrasive into the blade region, arranged radially further out, of the centrifugal wheel (not illustrated) over the entire width, with subsequent uniform acceleration as far as the exit from the blade. The blasting abrasive is substantially prevented from striking the blades and side walls of the centrifugal wheel. The impact-free transition of the blasting abrasive from the impeller 10, acting as a central accelerator, into the centrifugal wheel (not illustrated) brings about uniform guidance of the blasting abrasive in the centrifugal wheel. As a result, a uniform distribution of the blasting abrasive onto the surface to be treated is achieved. In addition the wear on the centrifugal wheel and also the energy to be applied for accelerating the blasting abrasive are reduced.
The illustrated impeller 10 has, as already indicated above, two different embodiments 20a, 20b of guiding members. The different embodiments are illustrated together in
The guiding members 20a, 20b are arranged on an end side of a first lateral disk 24. A second lateral disk (not illustrated) is arranged opposite and parallel to and spaced apart from the first lateral disk 24 in the axial direction, such that the guiding members 20a and 20b are positioned between the two lateral disks. It is noted in this connection that, in the context of the invention, the guiding members 20a and 20b can in principle be manufactured as separate components, but may of course also be connected in one piece to the respective end side of the lateral disks.
The guiding members 20a, 20b are raised with respect to the end-side plane of the lateral disk 24, i.e. they form elevations with respect to this plane. In principle, it is also conceivable to dispense with a second lateral disk and to use only one lateral disk.
The individual guiding members 20a, 20b are arranged in a manner distributed in the circumferential direction along an annular surface over the end side of the lateral disk 24. In the present case, the annular surface at the same time forms the peripheral region of the end side of the lateral disk 24.
Each guiding member 20a, 20b is spaced apart in the circumferential direction from the two guiding members 20a and 20b that are in each case immediately adjacent thereto on both sides.
The lateral surfaces 26a, 26b of the guiding members 20a, 20b extend firstly perpendicularly to the plane of the drawing and thus perpendicularly to the end side of the lateral disk 24 in the axial direction. In addition, the illustrated lateral surfaces 26a, 26b are directed toward the distributing sleeve 12 in the cross-sectional view in
At their ends 28a, 28b which are directed toward the impeller center 14 or toward the impeller rotational axis 16, or at their radially inner ends 28a, 28b, the lateral surfaces 26a and 26b are connected together via an underside 30. The underside forms a planar, i.e. non-curved connecting plane.
At their two upper, radially outer ends 32a, 32b, the lateral surfaces 26a, 26b are connected together via a top side 34a (guiding member 20a) or 34b (guiding member 20b). The top sides 34a and 34b likewise extend perpendicularly to the end side of the lateral disk 24, i.e. in the axial direction.
The contour of the respective top side 34a and 34b is particularly important. In the following text, first of all the contour 34a of the guiding member 20a is described.
The entire top side 34a extends above an imaginary reference plane 36, illustrated by way of dashed lines in
Like the entire guiding member 20a, the top side 34a is formed symmetrically to an axially extending longitudinal center plane 21. It has, on both sides of the longitudinal center plane 21, (non-curved) sections 38a and 38b which each adjoin the lateral-surface ends 32a, 32b. These non-curved sections 38a, 38b extend above the imaginary reference plane 36. In addition, the non-curved sections are inclined at an angle a with respect to the reference plane 36. The inclination extends in this case such that the pitch for example of the non-curved section 38a increases with respect to the reference plane 36, i.e. is positive. In this case, the viewing direction is defined as the direction starting from the lateral-surface end 32a adjacent to the non-curved section 38a toward the longitudinal center plane 21. In other words, the height of the non-curved section 38a increases with respect to the reference plane 36, specifically when viewed in said direction. In a similar manner, the pitch of the section 38b increases, specifically likewise with respect to the reference plane 36, but viewed in the opposite direction, i.e. starting from the lateral-surface end 32b adjacent to the non-curved section 38b toward the longitudinal center plane 21.
The two non-curved sections 38a, 38b are furthermore connected together by a connecting section 40. The latter is formed in a convex manner.
Overall, the result of the illustrated top-side contour of the guiding member 20a is that the space between the top side 34a and the sleeve section opposite the top side 34a, starting from the in each case leading—depending on the direction of rotation of the impeller—outer lateral-surface end 38a or 38b, first of all narrows to the smallest spatial volume at the connecting section 40 and subsequently widens again toward the trailing lateral-surface end.
The second embodiment of a guiding member 20b differs from the guiding member 20a by way of the contour of the top side 34b. Unlike in the case of the non-curved sections 38a, 38b of the guiding member 20a, the non-curved sections 38a, 38b of the guiding member 20b are not inclined with respect to the reference plane 36 but are located exactly within the reference plane 36.
In addition, the connecting section 40 that connects the two non-curved sections 38a, 38b is in the form of a type of projection: The two top-side sections 38a, 38b located in the reference plane 36 are adjoined by part-sections 42a and 42b of the connecting section 40, said part-sections 42a and 42b each extending perpendicularly to said top-side sections 38a, 38b but being arranged above the reference plane 36. A connecting part-section 42c that is in turn arranged likewise above the reference plane 36 and extends perpendicularly to said connecting part-sections 42a, 42b and also parallel to the sections 38a, 38b, in turn connects the connecting part-sections 42a, 42b together.
Tests by the applicant have shown that guiding members having a basic structure as illustrated and claimed in the scope of this application result, inter alia, in particularly long service lives of the respective impeller, particularly long service lives of the centrifugal wheel and a particularly uniform blasting abrasive pattern.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102010053172.3 | Dec 2010 | DE | national |
The application is the US PCT National Phase of International Application No. PCT/EP2011/005891 having an International Filing Date of 23 Nov. 2011, which claims priority on German Patent Application No. 10 2010 053 172.3 having a filing date of 3 Dec. 2010.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/005891 | 11/23/2011 | WO | 00 | 8/7/2013 |
