US3160992A

US3160992A - Abrasive blasting wheel

Info

Publication number: US3160992A
Application number: US294006A
Authority: US
Inventors: Ralph W Moore
Original assignee: Pangborn Corp
Current assignee: Kennecott Corp; Pangborn Corp
Priority date: 1963-07-10
Filing date: 1963-07-10
Publication date: 1964-12-15
Anticipated expiration: 1981-12-15

Description

R. W. MOORE ABRASIVE BLASTING WHEEL Dec. 15, 1964 Filed July l0, 1963 1 r1 wwwmain/ZZ '20 INVENTOR 1 dph llffoo r6 llnited States Patent @dice aisaaaz Patented Dee. 15, 1964 3,160,992 ABRASIVE BLASTING WHEEL Ralph W. Moore, Hagerstown, Md., assignor to rihe Pangborn Corporation, Hagerstown, Md., a corporation of Delaware Filed July 10, 1963, Ser. No. 294,006 13 Claims. (Cl. 51-9) The present invention relates to a blasting wheel which is used to project abrasive particles against work pieces for cleaning, descaling, peening or detlashing the work pieces. In particular, the invention relates to a new and novel blasting wheel, abrasive propelling vane and locking means for securing the vane to the wheel, whereby faster cleaning rates, particularly on sheet descaling installations, are provided.

The problem of getting faster cleaning rates per wheel, particularly with sheet descaling installations, has long vexed the blast cleaning industry. Cleaning rates depend upon the quantity of blast or shot applied per unit of time which can be efficiently applied at optimum velocity.

Blast wheels which are now used of the current conventional design have a rotating, hollow center impeller within a stationary control cage which emits abrasive and a rotating multi-vaned wheel which accelerates the emitted abrasive as it is advanced to the work pieces being treated. Generali these conventional wheels use a three-inch wide set of vanes and have a 19% inch outside diameter. When these wheels are driven at 2250 r.p.m. by a 25 H.P. motor they project approximately 40,000 pounds of steel shot per hour at approximately 240 feet per second. Four such wheels symmetrically mounted can descale a four-foot wide steel sheet, top and bottom, at a rate of about 20 l.f.m. and require approximately ten feet of installation length on the pass line. A reasonably desirable cleaning line speed is 300 l.f.m. which would require 15 tandem mounted four-wheel units using approximately 150 feet of pass line length. This pass line length requirement is not economical, is unhandy in many respects, and above all is not competitive with chemical descaling systems.

The ten feet of pass line length required by a fourwheel unit is a mechanical requirement and does not increase when wheels of greater capacity driven by greater horsepower motors` are used.

Renements of design have resulted in wheels having larger diameter feed elements and use five-inch wide t vanes with a 191/2 inch outside wheel diameter. When these wheels are driven at 2250 r.p.m. by a 75 HP. motor, they project approximately 120,000 pounds of steel shot per hour at approximately 240 feet per second. Four of these larger wheels, symmetrically mounted, can descale a four-foot wide steel sheet, top and bottom, at a rate of about 60 l.f.m. and not use more pass line length than the ten feet required by thersmaller capacity wheels. A 300 1.f.m. pass line speed would require ive tandem fourwheel units using approximately v feet of pass line length. Machines with as many as three tandem mounted four-wheel units using approximately 30 feet of pass line length have been built to clean at approximately 180 lim.

Five-inch wide vanes with 191/2 inch outside diameter wheels have been experimentally used'at 100 H P., but 'the expected pass line speed of 80 lfm. per four-wheel unit has not been realized and the required `flow of 160,000 pounds per hour has been difficult to attain.

Heretofore, the number of vanes has been limited to a maximum of eight by a combination of the small available space per vane at the inner end or the'center of the wheel, the necessity for an attachment design which is compatible with the hard, brittle, unmachinable characteristic of the material, and the need for easy replacement because of rapid Wear. With these previous designs, the impeller and the impeller case have lasted approximately 50% longer than the vanes.

The primary cause of reduced efficiency at high ilow and power has been found to be what is called abrasive saturation. This term is defined as the percentage ratio of the smallest area the shot from one vane can be fitted into, one layer thick, to the total area of the blast target. Abrasive saturation becomes a problem quickly in sheet descaling because the smallest sizes of abrasive (0.007- 0.017 inch diameter balls) are used. Abrasive saturation must be below 60% for eflicient descaling when using the 0.007 inch diameter abrasive balls.

Flow of large volumes of abrasive on the order of 200,000 pounds per hour can be readily obtained with larger diameter feed parts which require a large outside diameter to maintain the vane length for abrasive acceleration. The larger outside diameter requires, t0. maintain the desirable approximate 240 feet per second abrasive velocity, a reduction in rotational speed. The reduced speed means that a fewer number of vanes project abrasive per Vunit of time, thus increasing the amount of abrasive per vane, resulting in higher abrasive saturation and drastically reduced eiciency.

Vane widths can be further increased but six inches is a desirable maximum Width mechanically.

It is, therefore, a primary object of the present invention to provide a new and useful abrasive blasting wheel wherein a faster cleaning rate is achieved.

Another object is to provide a novel and improved abrasive blasting wheel wherein a greater number of vanes can be mounted on the wheel, for instance 12 vanes rather n than the conventional eight vanes.

Another object of the invention is to provide a novel and improved blasting wheel wherein the vanes thereof have increased life.

Still another object of the invention is to provide a blasting wheel of :the above objects which can be used for eitherclockwise or counterclockw-ise rotation, thus eliminating the need for separate vanes, impellers and control cages for each direction of rotation.

Still another object lis to provide a blasting wheel of the above objects which has a removable Wear ring on the wheel periphery which can be replaced when worn, thus eliminating the need to replace the entire runner head.

Another object is to provideran abrasive blasting wheel of the above objects which has no radial slots to concentrate abrasive wear at the attachment point which causes reduced life of the parts.

Still another object is to provide vane attachments for the above blasting wheel wherein the vanes can be lifted f out from'the runner head slots rather than drawn out by sliding them lengthwise ofthe slots.

Another object is to provide a new, novel and improved locking pin for holding the vanes in the blasting wheel.

Other objects and advantages of the invention will be-V come more apparent from a study of the following description and drawings wherein:

FlGURE 1 is a view of the face of the blasting wheel which supports the vanes and the vane locking means;

j FIGURE 2 is a view looking toward the periphery of the wheel of FGURE 1;

FIGURE 3 is a detail of the periphery of the wheel showing in dotted line the cross-sectional vshape of the vane supporting channels.

FIGURE 4 is an end view of the vanes used in the present invention;

FIGURES 5 and 5A are ViewsV of the locking means used for retaining the vanes inf the channels of the blasting wheel; Y

FIGURE 6 is a detail showing how the locking means for the vane lit or cooperate with the channel wall of the blasting wheel to maintain the vane in locked position on the wheel; and

FIGURE 7 is an embodiment of the wheel looking toward the periphery thereof.

Referring now specifically to the drawings, a blasting wheel disc 1 is shown in FIGURES 1 and 2 having radially extending vane mounting channels 2 which support vanes 3 so that the vanes extend outwardly from the face of the Wheel at right angles as shown better in FIG. 6. Here the channels terminate at a point just prior to the wheel periphery whereby a peripheral edge or dam 1 blocks off the vane channels 2 to prevent the vanes from sliding out during operation. As also shown in FIG. 1, the inner end of the vanes and channels terminate short of the wheel center and a circular shaped cutout C (FIG. 2) is provided in the wheel face at the Wheel center. Locking pins 4 have a U-shape and as shown better in FIGS. 5 and 5A are used to lock the vane in position once mounted in the vane channel 2. When in position (more about this later), the cross-leg 5 of the U-shaped pin is positioned adjacent the center of the blast wheel 1. An abrasive deecting plate 6 is mounted by retaining bolt 8 in the circular cut-out C of the wheel 1, and its rim portion 6' overlies the crossleg 5 of the locking pin 4 to prevent deflected or rebounding abrasive from working into the channels 2. The abrasive feed cage and impeller (not shown) are Supported over the dellector plate 6 whereby abrasive is fed into the innermost ends of the vanes.

FIG. 4 shows an end view of one of the vanes 3. Each side of the base 10 of the vane 3 is grooved longitudinally as shown to provide V-shaped grooves 12 which are directly opposite to one another. The top of the vane has a curved-over portion 3' to provide a channel shaped vane surface along which the abrasive travels. One advantage of this type vane and wheel is that the vanes can be used for either clockwise or counterclockwise rotation of the wheel by merely reversing the vane position in the channel.

FIG. 3 is a detail showing a portion of the periphery of the blast wheel 1. In dotted lines there are shown the channels 2 cut into the face of the wheel for supporting the vanes 3. Here the side walls of the channels are grooved longitudinally in V-shaped grooves 15 to provide directly opposed grooves, which are aligned with the grooves 12 of the vane base when the vane 3 is inserted in the channel 2. As seen better in FIG. 6, rectangular passageways 17 are formed by the opposing but mating grooves of the vanes 3 and the grooves 15 in the side walls of the vane channels 2.

The U-shaped locking pin 4 is inserted in the passageways 17 beginning at the innermost ends of the passageways to form a barrier or lock to prevent the vanes 3 from rising out of the vane channels 2.

IN FIG. 7 there is shown an embodiment of the wheel 1 whereby the peripheral portion housing the channels 2 is cut back to form a shoulder 20 and to expose the outer end of the vane channels 2. A replaceable wear ring 22 is fitted around the periphery of the blasting wheel 1 being supported by shoulder 20 thus also providing a darn for the vanes to prevent them from sliding out of the channel 2 during operation. With the use of the wear ring, the Wheel need not be replaced whenever the wheel periphery is damaged by deected abrasive since the ring 22 can merely be replaced.

In assembling the vanes in the blasting Wheel, the vanes are merely shoved downwardly into the vane channels 2 after which the locking pin 4 is inserted from the innermostend into the rectangular passageways 17. After the pin is inserted, the deilector plate 6 is then moved into position as shown inFIG. 2 and locked in place by retaining nut 8. A shoulder rim or peripheral portion 6 tits over` the cross-leg 5 of the U-shaped member 4 serving as a the locking pin.

The above described blasting wheel and vane assembly can be used with any number of vanes. One type of assembly includes eight vanes and another very satisfactory assembly will include l2 vanes.

The l2-vane blasting wheel assembly with an outside diameter of 2l inches with six-inch wide vanes can handle 200,000 pounds per hour of descaling shot at 125 H.P. whereby increased descaling efficiency results. At H.P. with 5.5 inch wide vanes 160,000 pounds per hour of shot can be projected with improved results.

In addition the 12-vane 2l-inch wheel with six-inch wide vane shows a saturation point of only 57% and at HP. rating is within what is known to be a reasonable saturation level.

The table set forth below shows the results when using wheels having the same diameter but using a different number of vanes and vanes of different widths. The three numbers in the top of each of the four columns are identified as the number of vanes, the diameter of the wheel and the width of the vane, in that order.

Function 8-21D- 8-21D- 8-21D- l2-2lD 5.5RI SRI GRI GRI Diameter (In.) 21 21 21 2l Width (In.) 5. 5 6 6 6 No. Vancs 8 8 8 12 Speed (r.p.m.) 2,100 2,100 2, 100 2,100 Horsepower 75 75 100 125 Vanes Per Sec 280 280 280 420 Abrasive Flow, Lb Per Hour 120, 000 120, 000 160, 000 200, 000 Abrasive Flow, Lb. Per

Hour Per ILP 1,600 1,600 1, 600 1,600 Abrasive (Gm 58. l 58.1 72. 3 60. 0 Per Vane (Lb.) 0.119 0.119 0.159 0.132 0.007" Dia. Balls Per Vane. 238)(104 238 l04 l17 l04 264)(104 0.007 Dia. Balls Per Inch Vane Width. v 433)(103 397)(103 530)(103 440)(103 Distance Between Waves of Abr. (In.) 8.25 8.25 8. 25 5. 5 Target Area (Sq. Iu.) 180 180 180 Minimum Target Area Covered by Abrasive One Vane 93 93 123 102 Saturation (Percent) 56 52 68 57 Vane tip velocity f.p.s 192 Abrasive velocity .f.p.s. 240 0.007 diameter balls per 1b-. 0X1()a Shot on target percent.. No. balls (0.0017 dia.) in one layer, per sq. in 21, 900

Obviously many modications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An abrasive blasting wheel comprising a rotatable wheel, radially extending vane channels in one face of the wheel which terminate just prior to the periphery of said wheel, abrasive propelling vanes inserted in said channels, which vanes extend vertically from said wheel face, longitudinally extending grooves in each side wall of each channel, longitudinally extending grooves in each side wall of the base of said vanes, said vane grooves and said channel grooves lying directly opposite each other to form passageways, and a U-shaped locking pin inserted in said grooves with the cross leg of the U-lying4 adjacent the center portion of the wheel.

2. An Iabrasive blasting wheel according to claim I wherein the vane channels extend to the wheel periphery, and a replaceable wear ring is atlixed around the periph-- ery of 'said wheel to block oit said channels and to absorb wear from deflected abrasive during operation.

3. An abrasive blasting wheel according to claim 2 wherein the wheel periphery is recessed to accommodate said wear ring.

4. An abrasive blasting wheel according to cla-im 1 wherein the vanes are reversible for either clockwise or counterclockwise rotation.

5. An abrasive blasting wheel according to claim l wherein a removable detlecting disc is alixed to the center of said wheel to cover the innermost ends of the locking means and the passagewaystherefore thus protecting the same from deflected abrasive.r

6. An abrasive blasting wheel according to claim 1 wherein the Vane and channel grooves are V-shaped grooves.

7. A rotatable wheel for supporting abrasive propelling vanes comprising vane supporting channels cut into one face of said wheel which terminate just prior to the wheel periphery, the top of each channel being at least as wide as the bottom of each channel whereby said vanes may be inserted directly downwardly into said channels and longitudinally extending grooves cut into the side-walls of said channels, said grooves lying opposite one another, which grooves cooperate with corresponding `grooves in the base Walls of said vanes to form passageways for accommodating a locking pin to lock said vanes in said channels. n

8. The wheel of claim 7 wherein the grooves are V- shaped.

9. A rotatable wheel according to claim 7 wherein a wear ring is aixed and extends around the wheel periphery.

10. A rotatable wheel according to claim 9 wherein le the wheel periphery is recessed to accommodate the wear ring.

11. The abrasive blasting wheel of claim 1 wherein twelve vanes are supported by the wheel.

12. The abrasive blasting wheel of claim 7 wherein twelve vane supporting channels are provided in said wheel.

13. An abrasive propelling vane for use with a rotatable blasting wheel and with a U-shaped locking pin disposed in a channel in said wheel with said channel being at least as wide at its top as it is at its bottom, said vane comprising an elongated blade having an abrasive propelling surface, a base supporting said blade, said base being at least as wide at its Itop as it is at its bottom whereby said base may be inserted directly downwardly into said channel, and a groove in each side of said base between said top and said bottom of said base for receiv- Lovenston Jan. 1, 1935 Gossard Jan. 20, 1959

Claims

1. AN ABRASIVE BLASTING WHEEL COMPRISING A ROTATABLE WHEEL, RADIALLY EXTENDING VANE CHANNELS IN ONE FACE OF THE WHEEL WHICH TERMINATE JUST PRIOR TO THE PERIPHERY OF SAID WHEEL, ABRASIVE PROPELLING VANES INSERTED IN SAID CHANNELS, WHICH VANES EXTEND VERTICALLY FROM SAID WHEEL FACE, LONGITUDINALLY EXTENDING GROOVES IN EACH SIDE WALL OF EACH CHANNEL, LONGITUDINALLY EXTENDING GROOVES IN EACH SIDE WALL OF THE BASE OF SAID VANES, SAID VANE GROOVES AND SAID CHANNEL GROOVES LYING DIRECTLY OPPOSITE EACH OTHER TO FORM PASSAGEWAYS, AND A U-SHAPED LOCKING PIN INSERTED IN SAID GROOVES WITH THE CROSS LEG OF THE U-LYING ADJACENT THE CENTER PORTION OF THE WHEEL.