US2869289A - Reversible centrifugal blasting method and apparatus - Google Patents

Description

Jan. 20, 1959 c. M. Gos'sARD 2,869,289

' REVERSIBLE CENTRIFUGAL BLASTING METHOD AND APPARATUS Filed Jan. 24, 1957 3 Sheets-Sheet 1 INVENTOR. Charles/H6055 card ATTORNEYS 1959 v c. M. GOSSARD ,86

REVERSIBLE CENTRIFUGAL BLASTING METHOD AND APPARATUS Filed Jan. 24. 1957 5 Sheets-Sheet 2 ATTORNEYS Jan. 20, 1959 c. in. eossARD REVERSIBLE CENTRIFUGAL BLASTING METHOD AND APPARATUS Filed Jan. 24, 1957- s SheetsSheet a INVENTOR QharZesMGoss ard B TTORNEYS REVERSIBLE CENTRIFUGAL BLASTING METHOD AND APPARATUS Charles M. Gossartl, Hagerstown, Md., assignor to Pangborn Corporation, Hagerstown, Md., a corporation of Maryland This invention relates to an abrading apparatus; and it more particularly relates to an abrading apparatus wherein abrasive particles are gathered and thrown against the workpiece by centrifugal force;

Centrifugal abrading machines of this type have been in extensive use for many years. They generally comprise a wheel having a runner-head on which are positioned vanes extending radially from the axial center of the runner-head. These vanes are connected, at one longitudinal edge, to the face of the runner-head, and project away from the face.

Abrasive particles are fed into a fixed cage positioned axially of the runner-head and surrounded by the vanes, and, as the wheel rotates, the abrasive particles are pro pelled out of the cage, through an opening therein, into the path of the rotating vanes. As each vane moves by the opening, it picks up a charge of abrasive and, as the vane continues to rotate, it propels the abrasive charge tangentially away from the peripheral portion of the wheel and against the workload which is in a position spaced from the wheel.

These vanes are generally made separable from the wheel so that they may be individually removed and replaced when necessary. This is important since the action of the abrasive particles produces rapid wear on the parts.

The throwing vanes described above are generally provided with a contour on one surface thereof which aids the impelling of the abrasive particles during the rotation of the Wheel. This contour is provided on that surface of the vanes corresponding to the direction of rotation of the wheel during use. Consequently, the

wheel can be operatively rotated in only one direction,

since, if it were rotated in the opposite direction, the vanes could not perform their function. It has, therefore, often been necessary, in order to get an adequate sweep of the abrasive stream, to provide at least two wheels, each being rotated counter to the other. This obviously tends to increase the cost of operation and maintenance. Furthermore, since no two wheels can be constructed exactly alike, there is always some variation in the abrasive effect, resulting in a lack of absolute uniformity of action over the entire workload.

On the other hand, if only one wheel is used, because of its unilateral direction of rotation, it is generallynecessary to over-abrade one side of theworkload in order to adequately abrade the other side. fact that where only one wheel is used, the hot spot" of the abrasive stream impinges against one portion of the workload while the tail-end of the stream impinges against the other end thereof. It is, therefore, necessary load which has been receiving the forward edge of the stream has been over-abraded.

wheel machines is the fact-that thevanes, during their This is due to the tatcs Patent i 2,869,289 Patented Jan. 20, 1959 rotation around the cage, tend to cut oifa large portion of the charge of abrasive particles projected outwardly through the opening in the cage. As a result, the abrasive stream issuing from the Wheel is substantially thinner than it sho-uldbe. Inother words, a large proportion of the abrasive particles which should take part in the blast stream is prevented from doing so. Conse-'- quently, the wheel must be run longer for each abrading operation in order to effect a sufficient cleaning action.

It is one object of the present invention to overcome the above as well as other disadvantages of the prior machines of this type by providing a centrifugal abrading" machine which will evenly distrbute the abrasive stream over the entire surface of the workload.

Another object of the present invention is to provide a centrifugal abrading machine wherein the time necessary' to effect an adequate cleaning is materially reduced.

Another object of the present invention is to provide acentrifugal' ab'rading machine wherein a maximum proportion ofthe abrasive supply i effectively used.

Other objects and many of the attendant advantages of this invention'wili be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a sectional View of a throwing wheel assembly embodyingthe present invention;

Fig. 2' is a sectional view taken on line 22 of Fig. 1;.

Fig. 3 is a top erspective view of one of the throwing vanes shown in Fig. 2;

Fig; 4 is a side view partly in secticn and partly in elevation, of the vane shown in Fig. 3, the vane being shown held on the runner-head;

Fig. 'S'is' an end elevational view of the vane shown in Fig 3;

Fig. 6' is a bottom plan view of the vane shown in Fig. 3";

Fig. 7 is a-diagramrnatic view showing the directions of the abrasive stream during operation of the device; s

Fig. 8 is a fragmentary elevational view of a modified form-of the present invention; and 7 Fig; 9 is a sectional view taken on line 9-9 of Fig. 8.

Referring now in greater detail to the figures of the drawings wherein similar reference characters refer to simiar parts, there is shown a runner-head it) mounted forrotation on a shaft 12. This shaft 12 extends through a housing 14, and is provided at its-other end, externally of the housing 14, with a driven sheave 16. A housing 18 encloses the runner-head it) and is provided with a central opening 253 to permit entrance of the shaft 12'as' Well as the flange 22 supporting the runner-head. uA. wear plate assembly 24- is releasably held in place to close the opening 2% to an extent suf icient to permit clearance for the shaft 12; An annular flange 26 projects from the inner surface of the Wear plate assembly and overlaps a" rib 23'on the outer surface of the runner-head assembiy;

The'runner-headis provided with a-central openingin. which is positioned a discharge-directing feed cage 30 which is of generally cylindrical or cup-shaped form. A feed slot 32 is provided on the side of theicage and within" the cage there is provided an impeller 34 that inclpdes'a' plurality of vanes 36.

" to hast the entire workload for a sufficiently long period to enable the tail-end side of the stream to effect aproper cleaning. By this time, that portion of the work-,

.70 Another serious defect in the prior type of centrifugal- The im eller is supplied with abrasive particlesby' means of thespout 42, and is rotated along with the runner-head; during such rotation, the abrasive particles are propelled by the vanes 36 through the slot' 32 into the path of the throwing vanes, to be hereinafter more fully described, as the vanes rotate with the runner-head The above-described structure is substantially similar to that disclosed in U. S. Patent No. 2,732,666, dated Jane" uary 31, 1956, and is described in greater detail in that} patent. I

The aforementioned throwing vanes, herein designated 44, are equally spaced around the runner-head and are releasably secured to the face of the runner-head as by a. dovetail connection. This dovetail connection is effected by a base 46 on the inner edge of each of the throwing vanes, this base being slidable in a corresponding channel 48 on the face of the runner-head.

The base 46 is generally wedge-shaped as is also the complementary channel. The base, itself, extends only partly along the corresponding edge of the blade portion 49, stopping short of the outer end of the blade portion, as best seen in Figs. 1, 3, 4 and 6. On its undersurface, the base is provided with a plurality of longitudinallyaligned slots 50, 52 and S4. The slot 50 opens out from that end of the base which stops short of the outer end or the blade portion.

When mounting or replacing a throwing vane 44 on the runner-head, the feed parts, at the center of the runner-head, are first removed. A leaf spring 56 is then placed under tension in the slot 52 of the base 46, after which the vane is inserted into the corresponding channel 48 from the outer periphery of the runner-head. It is then pushed toward the center of the runner-head until the foreshortened base 46 clears a square hole 58 which intersects the floor of the channel. A lock pin 60 is then dropped into the hole 58, and, since the lock pin is of greater length than the hole, it projects outwardly therefrom. The vane is then pulled radially back over the lock pin until the end wall 62 of the slot 50 abuts against the pin, thereby preventing any further radial movement of the vane.' The feed parts are then assembled in place in the center of the runner-head. For removal, the procedure is reversed.

In operation, the spring 56 holds the vane in tension until, during the rotation of the runner-head, centrifugal force pushes the vane hard against the lock pin.

Animportant aspect of this invention is the construction of the blade portion 49 itself. This blade portion, it should be noted, extends from a relatively narrow radial inner edge 64 to a relatively wide outer edge 66, as can best be seen in Fig. 2. At that edge of the blade portion which is opposite the base 46, there are provided a pair of oppositely extending ribs or flanges 68. Similar ribs or flanges 69 are provided adjacent the base. Each of these ribs 68 and 69 is coextensive in length with the corresponding impelling surface 70 of the blade portion, there being an impelling surface on each side of the blade portion, and is provided for the purpose of preventing the abrasive from escaping laterally from its corresponding impelling surface.

With the above-described construction, a single throwing wheel can be used to effectively and efiiciently clean a; workload. This is accomplished by rotating the wheel in one direction for one predetermined time interval and then reversing the direction of rotation for a second predetermined time interval. This reversal of movement may be continued for a number of passes, if desired.

The compound action of the abrasive stream in both directions is illustrated in Fig. 7 where the fan-shaped stream A, shown in full line, is projected against the workload during clockwise operation of the wheel and the fan-shaped stream B, shown in dotted outline, is projected against the workload during the counterclockwise operation of the wheel. It can be seen that with a workload within the limits shown at C and D, practically the entire workload, within the area E, receives an equal abrasive action.

During the operation of this device, not only is the workload efiectively cleaned, but the abrasive effect is more pronounced and the cleaning action is more rapid due' to the tapering construction of the vanes. This tapered construction, which provides a relatively narrow, inner vane portion adjacent the cage, greatly decreases the blockage of the cage opening during rotation of the The runner-head 100 in Figs. 8 and 9 is provided with a plurality of radial channels 102 similar to the aforethe first described form of the invention.

mentioned channels 48. Each channel 102 is intersected, adjacent its outer end, by a bore 104 extending completely through the runner-head from rear to front.

Adapted to be inserted through said bore 104 is a locking pin 106 of substantially smaller cross-sectional width than the bore and having a flange 108 projecting laterally out from one end thereof. The cross-sectional width of this flanged end is slightly less than that of the bore to permit its insertion and extraction through the bore.

The throwing vane 110 used in this modified form is provided with a base 112 similar to base 46 except that, I

having a cross-sectional width corresponding to that of the bore 104.

To position a throwing vane 110 on the runner-head V 100, it is not necessary to remove the feed parts as in Instead, it is merely necessary to insert the base 112 of the vane into its corresponding channel 102 and to move it radially inward of the runner-head until the slot 114 fully mates with the end of bore 104. In this position the vane will either still be slightly spaced from the feed cage or may even be in light contact therewith. The locking pin 106 is then inserted through the bore 104 until the flanged end 108 is seated within the slot 114. The vane is then pulled back, removing the slot 114 from its mating position with bore 104 and pulling the flange 108 over the shoulder defining the end of the bore. This is the locked position and is illustrated in Fig. 9. Centrifugal force holds the parts in this locked position during operation, just as in the first described form of the invention.

When it is desired to remove any one of the vanes 110, the above procedure is reversed whereby the vane is pushed toward the center, the locking pin 106 is withdrawn, and the vane is then slid out of the corresponding channel radially outward of the runner head. 1

Obviously many modifications 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 throwing vane comprising an elongated base adapted to be connected to a centrifugal throwing wheel, a blade connected to said base, said blade extending the entire length of said base and having an extension which extends beyond the corresponding end of said base, said blade being defined by two generally flat throwing surfaces, one on each side, said throwing surfaces being inwardly inclined toward each other from a relatively wide edge of said blade at the end of said extension to a relatively narrow edge at the opposite end of said blade, the longitudinal edge of said blade remote from said base being provided with a pair of oppositely-extending lateral flanges extending along the length of said blade, said flanges defining a flat longitudinal blade edge tapering from a relatively wide end 1 coincident with the relatively wide edge of said blade at the end of said extension to a relatively narrow end co incident with the relatively narrow edge at the opposite- 3. The throwing vane of claim 1 wherein said base is provided with a longitudinal bottom wall remote from said blade, a first recess in said bottom wall for holding a leaf spring under tension, and a second recess in said bottom wall spaced from said first recess and having an open end coincident with the edge of the base adjacent the extension of said blade.

4. An abrasive throwing wheel comprising a runnerhead, means for rotatably connecting said runner-head to a driving means, radially extending abrasive-impelling vanes on one face of said runner-head, said vanes each comprising a radially extending elongated base having a rear Wall and a front wall, said rear wall being connected to said one face of said runner-head, and an elongated blade extending from the front wall of said base in a direction parallel to the axis of said runnerhead, each of said blades being tapered inward from a relatively wide end at the radially outer edge thereof to a relatively narrow end at the radially inner edge thereof, and coacting securing means on said runner-head and on each base for releasably securing the base to the runner head, said securing means being entirely positioned between said one face of said runner-head and the rear wall of the base within the plane defined by the opposite longitudinal edges of the base.

5. The throwing wheel of claim 4 wherein the longitudinal edge of each blade remote from the respective base is defined by a pair of oppositely extending lateral flanges extending the full length of said blade and tapering along therewith, said longitudinal edge of the blade being unconfined.

6. The throwing Wheel of claim 4 wherein the base of each vane is slidably positioned in a radially extending channel on said one face of the runner-head.

7. The throwing wheel of claim 4 wherein said securing means includes an open-ended longitudinal slot on the rear wall of each base, said slot opening out of the radially outer end of the base, and a removable locking pin extending outwardly from said one face of the runner-head and into said slot.

8. The throwing wheel of claim 4 wherein said securing means comprises a longitudinal slot in the rear wall of each base, said slot opening out of the radially outer end of the base, a removable locking pin insertable through a bore in said runner-head, said bore extending parallel to the axis of said runner-head, said locking pin having a laterally flanged end thereon insertable within said slot, the length of the slot being substantially the same as the width of the bore, and the width of the locking pin being substantially smaller than the width of the bore.

References Cited in the file of this patent UNITED STATES PATENTS 1,849,895 Walters Mar. 15, 1932 2,582,702 Keefer Jan. 15, 1952 2,732,666 Powell Jan. 31, 1956 2,819,562 Barnes Jan. 14, 1958

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