WO2017061989A1

WO2017061989A1 - System and method for timing impeller vanes with blades in a blast wheel machine

Info

Publication number: WO2017061989A1
Application number: PCT/US2015/054210
Authority: WO
Inventors: Ronald G. Barrier; Lawson PRYKE; Stanislav VENCLIK; Stepan KAPSA; Philipp WEISSENBERGER; Michael Dwayne REAVES; Jürgen WRUCK; Christoph BÄR
Original assignee: Wheelabrator Group Ltd
Current assignee: Wheelabrator Group Ltd
Priority date: 2015-10-06
Filing date: 2015-10-06
Publication date: 2017-04-13
Anticipated expiration: 2018-04-06

Abstract

A centrifugal blast wheel machine includes a wheel assembly having blades configured to throw blast media introduced into the wheel assembly against a work piece. An impeller driven by a motor is positioned about an axis of the wheel assembly. The impeller has a media inlet at one end adapted to receive blast media and a plurality of impeller media outlets constructed and arranged to allow egress of blast media upon rotation of the impeller. A control cage surrounds the impeller and is secured to the wheel assembly. The control cage includes a cylindrical body defining an interior chamber. The cylindrical body has an opening formed therein to allow the egress of blast media from the interior chamber. A timing of the impeller is advanced in relation to a corresponding blade to achieve a considerable effect on both the distribution and intensity of a blast wheel blast pattern.

Description

SYSTEM AND METHOD FOR TIMING IMPELLER VANES WITH BLADES IN

A BLAST WHEEL MACHINE

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The present disclosure relates generally to abrasive blast wheels and methods for cleaning or treating surfaces of work pieces, and more particularly to a system and method for timing impeller vanes of a centrifugal blast wheel machine with a control cage of the centrifugal blast wheel machine.

2. Discussion of Related Art

Centrifugal blast wheel machines generally include a rotatable wheel having a plate or a pair of spaced plates that carry radially extending blades. Particulate matter is discharged from a center of the blast wheel onto rotating surfaces of the blades, which propel the particulate matter against surfaces of a work piece to be cleaned or treated. Specifically, blast media is fed from a feed spout into a rotating impeller situated within a control cage at the center of the blast wheel. The media is fed from the impeller, though an opening in the control cage, and onto the heels or the inner ends of the rotating blades. The media travels along the faces of the blades and is thrown from the tips of the blades at the work piece surfaces to be treated.

Blast wheel machines having incorrectly designed impellers have issues with blast media striking a pickup point of the blade (sometimes referred to as the "heel"), thereby impeding a continuous flow of media onto the blade face to be thrown at the work piece. This phenomenon is sometimes referred to as "dead heading" into the blade pick up point. Indeed, in higher horsepower applications, this configuration results in premature choking of the blast wheel, so that the blast wheel is impeded from throwing a full amount of media that it is rated for at that horsepower. A pickup point of a semi-curved blade is necessarily elongated in its curved inner section, which increases the possibility of "dead heading." SUMMARY OF THE DISCLOSURE

One aspect of the present disclosure is directed to a centrifugal blast wheel machine comprising a wheel assembly having a plurality of blades configured to throw blast media introduced into the wheel assembly against a work piece. The centrifugal blast wheel machine further comprises an impeller positioned about an axis of the wheel assembly, with the impeller having a media inlet at one end adapted to receive blast media and a plurality of impeller media outlets constructed and arranged to allow egress of blast media upon rotation of the impeller. The centrifugal blast wheel machine further comprises a motor coupled to the impeller to drive the rotation of the impeller and the wheel assembly. The centrifugal blast wheel machine further comprises a control cage surrounding the impeller and secured to the wheel assembly. The control cage includes a cylindrical body defining an interior chamber. The cylindrical body has an opening formed therein to allow the egress of blast media from the interior chamber. A timing of the impeller is advanced in relation to a corresponding blade to achieve a considerable effect on both the distribution and intensity of a blast wheel blast pattern.

In certain embodiments, the impeller is advanced in relation to the corresponding blade by 0 to 45 degrees, preferably advanced in relation to the corresponding blade by 30 to 35 degrees, and most preferably advanced in relation to the corresponding blade by approximately 32.5 degrees. In one embodiment, each blade includes a curved portion positioned adjacent a central hub of the wheel assembly, and a straight portion integrally formed with the curved portion extending radially outwardly from the wheel assembly.

Another aspect of the disclosure is directed to a method of operating a centrifugal blast wheel machine. In one embodiment, the method comprises: feeding blast media from a feed spout into an impeller of the centrifugal blast wheel machine; accelerating the blast media by rotating the impeller giving rise to a centrifugal force that moves the blast media in radial direction, away from an axis of the impeller; moving the blast media in a generally circular direction into a space between the impeller and a control cage;

metering an amount of blast media through an opening of the control cage onto blades of a blast wheel; and moving the blast media along lengths of the blades to accelerate and throw the blast media toward a work piece. A timing of the impeller is advanced in relation to a corresponding blade to achieve a considerable effect on both the distribution and intensity of a blast wheel blast pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

FIG. 1 is a perspective view of a portion of a centrifugal blast wheel machine;

FIG. 2 is another perspective view of the centrifugal blast wheel machine;

FIG. 3 is an exploded perspective view of the centrifugal blast wheel machine;

FIG. 4 is a perspective view of a feed spout of the centrifugal blast wheel machine;

FIG. 5 is a perspective view of an impeller, a control cage, and blades of the centrifugal blast wheel machine;

FIG. 6 is an end view of the arrangement shown in FIG. 5;

FIG. 7 is an enlarged end view of the arrangement shown in FIG. 6; and

FIG. 8 is a further enlarged end view of the arrangement shown in FIG. 7.

DETAILED DESCRIPTION

The blast wheel of embodiments of the present disclosure is designed to throw metallic shot, grit, cut wire, etc., which together may be referred to as "abrasive," "abrasive blast media," "abrasive media," "blast media," "media" or any suitable description of particulate matter. The blast wheel machine typically consists of four primary components that act in conjunction to throw the media at a target object to be cleaned, peened or otherwise have its surface prepared. An impeller acts to accelerate the abrasive media once the media is fed into a wheel assembly. The impeller rotates within the interior of a control cage, which may also be referred to as an "impeller case." The control cage acts to meter the abrasive blast media flow through an opening formed in the control cage to direct the flow of media onto rotating blades by adjusting the position of the opening. The control cage is stationary within the blast wheel under operating conditions. The blades (generally from two to twelve in number) rotate outside of the control cage and propel the abrasive blast media along their radial length toward the target. A bare wheel, which may also be referred to as a "runner head" or simply as a "wheel," holds the impeller and blades, and typically rotates the impeller and blades between 1500-3600 revolutions per minute (rpm) by way of a power source, which in one embodiment is an electric motor.

Embodiments of the present disclosure are directed to optimizing the timing of impeller vanes (also known as dams) with the wheel blades to increase the efficiency of the transfer of blast media from the impeller to a pickup point of the blades. Timing of the impeller with the blades refers to the position of the impeller vanes and openings in relation to the blades. The majority of blades used within the industry are of a straight design that radiate from the centerline of the blast wheel. With this arrangement, the blast wheels configure the centerline of the blades directly in line with the centerline of the impeller vanes. When using a semi-curved blade, a flow of media onto the blade is optimized when the impeller opening is advanced forward of the blade pick up by some degree. The overall increase in efficiency of the impeller is offered in conjunction with the more efficient and gentler pick up of the semi curved blade to improve the transition of the media flow from the impeller onto the blade.

By providing a smoother transition of blast media from the impeller to the blades, more of the media arrives on target at the designed velocity, resulting in better efficiency of the blast wheel. Also, by introducing the media in advance of the blade, the media transitions onto the semi-curved section of the blade, with less impact on the bottom and back of the blade. This results in better wear life of blades, especially in the pickup area. Blades are the most frequently replaced wear parts within a blast wheel, so that better wear life translates into less expense on blades. Additionally, the combination of advanced timing and semi-curved blades results in a gentler transition of media through the blast wheel. Previous testing suggests that as much as 28-30% of media consumption takes place within the blast wheel. This, coupled with the high cost of media, results in significant savings for the operator.

Referring to the drawings, and more particularly to FIGS. 1-3, a centrifugal blast wheel machine is generally indicated at 10. In one embodiment, the centrifugal blast wheel machine 10 includes a housing, generally indicated at 12, which is designed to house the components of the centrifugal blast wheel machine. The centrifugal blast wheel machine 10 further includes a rotating impeller 14 supported by a drive shaft, a control cage assembly, generally indicated at 16, which surrounds the impeller, and a blast wheel assembly, generally indicated at 18, which receives the control cage assembly. A motor 20 is provided to drive the rotation of the impeller 14 and the blast wheel assembly 18. The arrangement is such that blast media is fed from a feed spout 22 into the rotating impeller 14, which is driven by the motor 20. By contact with vanes of the rotating impeller 14 (as well as with other particles of media already in the impeller), blast media particles are accelerated, giving rise to a centrifugal force that moves the particles in radial direction, away from the axis of the impeller. The blast media particles, now moving in a generally circular direction as well as outwards, move through openings 15 formed in the impeller 14 into a space between the impeller and a control cage of the control cage assembly 16, still being carried by the movement of the impeller vanes (also known as impellor dams) and the other particles.

When the blast media particles that have passed though the impeller openings 15 into the space between the impeller 14 and the control cage assembly 16 reach an opening provided in the control cage assembly, rotational and centrifugal forces move the particles through the opening and onto ends of the vanes. The control cage assembly 16 functions to meter a consistent and appropriate amount of blast media onto the blades of the blast wheel assembly 18. As the vanes of the impeller 14 rotate, the blast media particles are moved along their lengths and accelerate until they reach the ends of the vanes and thrown from the ends of the vanes. Although the impeller 14 is shown to be cylindrical in shape, the size and thickness of the impeller may vary depending on the size of a blast wheel assembly and the desired performance characteristics. For example, the impeller 14 may have interior or exterior walls that taper in either direction along its axis. Typically, the impeller will be made of a ferrous material, such as cast or machined iron or steel, although other materials may also be appropriate. In one particular embodiment, the impeller is formed of cast white iron.

The blast wheel assembly 18 of the centrifugal blast wheel machine 10 includes a hub or wheel 24 and a plurality of blades, each indicated at 26, to throw blast media introduced into the wheel assembly to treat the work piece contained within the housing 12. The arrangement is such that the impeller 14 is positioned about an axis of the wheel 24 of the blast wheel assembly 18, with the impeller having a media inlet 27 (FIG. 5) at one end adapted to receive blast media and a plurality of impeller media outlets constructed and arranged to allow egress of blast media upon rotation of the impeller. The control cage of the control cage assembly 16 surrounds the impeller 14 in a position in which the media outlet of the control cage assembly is adapted for passage of blast media to the heel ends of the blades of the blast wheel assembly 18. As mentioned above, the motor 20 is coupled to the impeller 14 and to the blast wheel assembly 18 to drive the rotation of the impeller and the wheel assembly.

Referring additionally to FIG. 5, the present disclosure is directed to the control cage assembly 16 for the abrasive blast wheel assembly 18 that is configured to lock a control cage of the control cage assembly in place. In one embodiment, the control cage assembly 16 of the present disclosure includes a control cage 28 having a cylindrical wall 30 forming a housing defining an interior chamber and a media outlet or opening 32 formed in the cylindrical wall for allowing the egress of blast media from the interior chamber. A typical centrifugal blast wheel machine 10 having the control cage 28 is used to treat a surface (not shown) of a work piece by projecting blast media (not shown) at the surface. The treatment may be in the nature of cleaning, peening, abrading, eroding, de-burring, de-flashing, and the like, and the blast media typically consists of solid particles such as shot, grit, segments of wire, sodium bicarbonate, or other abrasives, depending on the surface being treated and/or the material being removed from the surface.

The control cage 28 of the control cage assembly 16, typically formed of cast iron (or similar material), is positioned concentrically around impeller 14 and, is approximately cylindrical in shape. Like the impeller 14, however, the control cage 28 may have other shapes, and may, for example, taper internally and/or externally in either direction along its axis. The control cage 28 also includes an outer flange or locking ring 34, which mates with an adaptor plate 36, which in turn is mounted on the wheel 24 of the blast wheel assembly 18, fixing the control cage with respect to the wheel and preventing the control cage from rotating with respect to the wheel upon operation of the blast wheel assembly 10. A retaining ring 38 is further provided to firmly secure the locking ring 34 and to prevent the rotational movement of the control cage 28 with respect to the adaptor plate 36 after securing the adaptor plate to the blast wheel 24 of the blast wheel assembly 18. The control cage 28 is then locked in place by placing the feed spout 22 onto the control cage and by firmly securing a feed spout bracket 40, which is shown in FIG. 4.

In other embodiments, the control cage 28 may be restrained from movement by attachment to other stationary elements of the blast wheel assembly 18 or its environment (as indicated above), or, in some cases, may be allowed to or made to rotate in one or both directions. As shown, one of two retaining rings 38 may be provided, with one of the retaining rings having markings or other indicia that allow a user to position the control cage 28 in a certain desired rotational orientation, so as to control the direction of the media being thrown by the blast wheel assembly 18.

As mentioned above, the media opening 32 of the control cage 28 allows egress of blast media upon operation of the blast wheel assembly 18. In the illustrated embodiment, the media opening 32 is approximately rectangular in shape when viewed from the side (i.e., in a direction perpendicular to its axis) and is approximately 3/5 the height of the cylindrical wall 30 of the control cage 28. The size, shape, and location of the media opening 32 may vary depending on the application, however. The length of the media opening 32 is measured in degrees, from the innermost portion of the opening furthest ahead in the direction of rotation to the outermost edge of the trailing portion. While the media opening 32 of the shown embodiment is approximately seventy degrees for a wheel rotating in either direction, in other embodiments, the length of the opening (in either direction) may vary, depending numerous factors such as the overall size of the blast wheel assembly 18, the nature of the media being thrown, and the desired rate of flow, as would be understood by one of skill in the art.

Referring back to FIGS. 1-3, the blast wheel assembly 18, which is arranged concentrically around control cage 28, includes the plurality of blades 26 sandwiched between a rear wheel and a front wheel of the wheel 24 of the wheel assembly. The various parts of blast wheel assembly 18 are typically formed of cast iron, although they may also be made of any other appropriate material and/or method. The blast wheel assembly 18 is connected to the motor 20, in this embodiment by means of key inserted to lock a shaft of motor to the rear wheel of the wheel assembly, so that wheel assembly may be rotated by motor during operation of the blast wheel assembly. Blades 26, each of which have a heel end and a tip, are constructed and arranged to direct the blast media at the surface being treated. The blades 26 may be of any suitable size and any suitable shape, including one or more of straight, curved, flared, flat, concave, or convex shapes.

In one embodiment, the blades 26 may embody semi-curved blades, each blade having a curved portion positioned adjacent a central hub of the wheel assembly 18, and a straight portion integrally formed with the curved portion extending radially outwardly from the wheel assembly. Reference can be made to FIG. 5 which shows the semi- curved blades 26.

The invention is primarily focused on blast wheel applications that throw metallic shot, grit, cut wire, etc. As discussed above, a blast wheel typically consists of four primary components that act in conjunction to throw the blast media at a target object to be cleaned, peened or otherwise have its surface prepared. These components are the impeller 14, the control cage 28, the blades 26, and the blast wheel 24.

Referring to FIG. 6, an end view of the impeller 14, the control cage 28, and the blades 26 are shown. The impeller 14 and the blades 26 are configured to rotate with respect to the control cage 28. Referring to FIGS. 7 and 8, the impeller 14 is positioned with respect to a corresponding blade 26a. As shown, the orientation of the impeller 14 is advanced with respect to the blade 26a. Embodiments of the present disclosure are directed to advancing the timing of the impeller 14 in relation to the corresponding blade 26a to achieve a considerable effect on both the distribution and intensity of the blast wheel blast pattern. When using a semi-curved blade, such as blade 26a, the timing of the impeller 14 is critical to achieve the optimal transfer of blast media onto the blade. For semi-curved blades, such as blade 26a, the advancement can range from 0 to 45 degrees. In FIGS. 7 and 8, this advancement is represented by the angle X between axis A and axis B. As shown, axis A extends through a center of the impeller vane (dam) 42. Axis B extends through center mass of blade 26a. In a certain embodiment, the advancement of the timing of the impeller 14 in relation to the corresponding blade, e.g., blade 26a, is approximately 32.5 degrees, with a desired amount of optimization for different configurations of pickup points. The media is efficiently conveyed through the openings 15 in the impeller 14 in a controlled manner so that the semi-curved blade, e.g., blade 26a, can most effectively "pick up" the media as it rotates past the control cage opening 32.

By advancing the impeller 14, the distribution and intensity of a blast pattern of the blast wheel assembly 18 having blades 26 is improved when the timing of the impeller openings 15 was optimized with corresponding blades. A result is that the blast media thrown by the blast wheel assembly 18 is better controlled and focused. The blast wheel assembly 18 is more efficient, and can produce an equal amount of work while throwing less blast media. Additionally, the greater efficiency and control result in less consumption of blast media within the blast wheel assembly 18. The blast media is subjected to less high speed contact with blast wheel components as it is conveyed in a controlled manner from the impeller openings 15 to the blades 26. Also, the improved timing results in less blast media striking the bottom or back side of the blades.

The operation of the centrifugal blast wheel machine 10 is as follows. The blast media is fed from the feed spout 22 into the rotating impeller 14. By contact with the rotating impeller vanes (as well as with other particles of media already in the impeller 14), the blast media particles are accelerated, giving rise to a centrifugal force that moves the particles in radial direction, away from the axis of the impeller. The blast media particles, now moving in a generally circular direction as well as outwards, move through the impeller openings 15 into the space between the impeller 15 and the control cage 28, still being carried by the movement of the impeller vanes 42 and the other particles. When the blast media particles that have passed though the impeller openings 15 into the space between the impeller 14 and the control cage 28 to the media opening 32, the rotational and centrifugal forces move the particles through the media opening and onto the heel ends of the blades 26. The control cage 28 functions to meter a consistent and appropriate amount of blast media onto the blades 26. As the blades 26 of the blast wheel 24 rotate, the blast media particles are moved along their lengths and accelerate until they reach the tips, at which point they are thrown from the ends of the blades toward the work piece.

Embodiments of the impeller can be modified as required. The degree of advancement of the impeller opening in relation to the blade is not limited to the 32.5 degrees; however, this amount is desirable as a starting point. While particularly useful with semi-curved blades, the concepts of the present disclosure are not limited to semi- curved blades, but can be used for traditional blades. Advantages include a smoother flow of media from the impeller to the blades, better wear life of blades, especially in the pickup area, and improved media consumption.

Having thus described several aspects of at least one embodiment of this disclosure, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the disclosure. Accordingly, the foregoing description and drawings are by way of example only.

What is claimed is:

Claims

1. A centrifugal blast wheel machine comprising:

a wheel assembly having a plurality of blades configured to throw blast media introduced into the wheel assembly against a work piece;

an impeller positioned about an axis of the wheel assembly, the impeller having a media inlet at one end adapted to receive blast media and a plurality of impeller media outlets constructed and arranged to allow egress of blast media upon rotation of the impeller;

a motor coupled to the impeller to drive the rotation of the impeller and the wheel assembly; and

a control cage surrounding the impeller and secured to the wheel assembly, the control cage including a cylindrical body defining an interior chamber, the cylindrical body having an opening formed therein to allow the egress of blast media from the interior chamber,

wherein a timing of the impeller is advanced in relation to a corresponding blade to achieve a considerable effect on both the distribution and intensity of a blast wheel blast pattern.

2. The centrifugal blast wheel machine of claim 1, wherein the impeller is advanced in relation to the corresponding blade by 0 to 45 degrees.

3. The centrifugal blast wheel machine of claim 1, wherein the impeller is advanced in relation to the corresponding blade by 30 to 35 degrees.

4. The centrifugal blast wheel machine of claim 1, wherein the impeller is advanced in relation to the corresponding blade by approximately 32.5 degrees.

5. The centrifugal blast wheel machine of claim 1, wherein each blade includes a curved portion positioned adjacent a central hub of the wheel assembly, and a straight portion integrally formed with the curved portion extending radially outwardly from the wheel assembly.

6. An impeller for a centrifugal blast wheel machine, the impeller comprising a media inlet at one end adapted to receive blast media and a plurality of impeller media outlets constructed and arranged to allow egress of blast media upon rotation of the impeller, a timing of the impeller being advanced in relation to a corresponding blade to achieve a considerable effect on both the distribution and intensity of a blast wheel blast pattern.

7. The impeller of claim 6, wherein the impeller is advanced in relation to the corresponding blade by 0 to 45 degrees.

8. The impeller of claim 6, wherein the impeller is advanced in relation to the corresponding blade by 30 to 35 degrees.

9. The impeller of claim 6, wherein the impeller is advanced in relation to the corresponding blade by approximately 32.5 degrees.

10. A method of operating a centrifugal blast wheel machine, the method comprising:

feeding blast media from a feed spout into an impeller of the centrifugal blast wheel machine;

accelerating the blast media by rotating the impeller giving rise to a centrifugal force that moves the blast media in radial direction, away from an axis of the impeller; moving the blast media in a generally circular direction into a space between the impeller and a control cage;

metering an amount of blast media through an opening of the control cage onto blades of a blast wheel; and

moving the blast media along lengths of the blades to accelerate and throw the blast media toward a work piece, wherein a timing of the impeller is advanced in relation to a corresponding blade to achieve a considerable effect on both the distribution and intensity of a blast wheel blast pattern.

11. The method of claim 10, wherein the impeller is advanced in relation to the corresponding blade by 0 to 45 degrees.

12. The method of claim 10, wherein the impeller is advanced in relation to the corresponding blade by 30 to 35 degrees.

13. The method of claim 10, wherein the impeller is advanced in relation to the corresponding blade by approximately 32.5 degrees.

14. The method of claim 10, wherein each blade includes a curved portion positioned adjacent a central hub of the wheel assembly, and a straight portion integrally formed with the curved portion extending radially outwardly from the wheel assembly.