US 2108211 A
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Description (OCR text may contain errors)
Feb. 15, 1938. w. A. ROSENBERGER ET AL 2,108,211
ABRADING MACHINE Original Filed May .7, 1934 amen mi 1 31 w myw Patented Feb. 15, 1938 UNITED STATES ABBADING MACHINE William A. ltosenberger and Walter L. Keefer,
Hagerstown, Md., assignors to Pangborn Corporation, a corporation of Maryland Original application May 17, 1934, Serial No. 726,-
188. Divided and this application August 29,
1936, Serial No. 98,599
8 Claims. (01. 51-9) The present invention relates to centrifugal abrading apparatus. More particularly, the present invention is concerned with an abradin machine of the character wherein the abrasive is picked up and directed against the work by sliding the abrasive over blades removably secured to a rotor.
In centrifugal abrading maclfines of the general character already referred to, the blades wear out rapidly under the action of the abrasive, and must be frequently replaced by new ones, necessitating the stopping of the machine at quite frequent intervals. 1
It is the primary object of the present invention to construct a centrifugal abrading machine so that the blades may bev readily removed and new ones substituted.
A further object of the present invention resides in providing the runner-head of a centrifugal D abrading machine with abutment means for positively preventing outward movement of the impeller blades when the machine rotates at high speed.
A still further important object of the present a invention resides in providing an improved blade structure having exceptional wearing quality and a rugged attaching portion formed so as to be readily slidably interlocked to the runner head of the rotor.
It is another object of this invention to provide an improved blade structure designed to permit easy assembly there with of a spring to retain the blades in position after slidable assembly with the runner head. 35 Another object of this invention resides in providing a centrifugal blasting machine with a runner-head formed to provide undercut grooves through which the abrasive impelling elements may be slid in or out of place thus facilitating rapid changing of the blades.
Further objects of the present invention will become apparent as the detailed description thereof proceeds in connection with the annexed draw ing, and from the appended claims.
In the drawing:
Figure l is a longitudinal sectional view through the runner-head and easing of the present invention;
Figure 2 is a sectional view taken substantially on the line 2-2 of Figure 1;
Figure 3 is a side elevational view of one of the main impeller blades employed in the device shown in Figure l; r g
Figure 4 is a detailed sectional view taken substantially on the line 4-4 of Figure 2.
the upper portion of centrifugal impeller or rotor able manner.
With continued reference to the drawing wherein like reference characters have been employed to designate like parts throughout the several views thereof, the machine is supported upon a base designated generally at l0. Base It) may be 5 supported in any desired manner although it preferably is secured to the upper side of a sand blasting cabinet (not shown) in the manner disclosed in the copending application of William A. Rosenberger and Walter L. Keefer, Serial No. 726,188, filed May 17, 1934, of which the present application is a division.
A housing I3 is secured to the lower side of base ill by means of cap screws l4, and a complemental housing member i5 is secured to base l5 ill in spaced relation to housing l3 by means 0 cap screws 16. Housings l3 and I5 house the lower part of an impeller or rotor ll to be hereinafterdescribed in detail.
An upper housing member I8 is secured to the upper side of base ill by means of nut and bolt assemblies (not shown) and is provided with a pair of handles (not shown) by which it may be lifted when it is detached from the base. Since the bolt assemblies and handles are described in detail in the above mentioned copending application and form no part of the present invention, a disclosure and description thereof in this application is not necessary. Housing l8 encloses H and is preferably provided with ,a removable wear element which takes the form of a semicylindrical ring 2|, which may be detachably secured thereto in any suitable manner.
A shaft 25 is mounted for rotation upon base Ill, and power may be applied to it in any suit- Sliait 25 is provided with an annular groove 26 and extends through semi-circular recesses 21 and 28 located respectively in housing l8 and base l0. Secured to a reduced portion 29 of shaft 25 by means of a key 3 I is .a runner-head 32, which supports all of the rotating elements of the blasting machine. Runner-head 32 is provided with an annular flange 33 or equivalent means that cooperates with the impeller blades in a manner to be hereinafter described.
Secured to head 32, as by means of bolt and nut assemblies 34, are a plurality of guide blocks 35 which are provided with inclined faces 36. With particular reference to Figure 4, the neighboring sides of blocks 35 form dove-tail or undercut grooves adapted to retain theabrasive impelling blades.
A plurality of blade members 31 are mounted upon head 32 and are provided with dove-tailed portions 33 which are disposed within the guide grooves defined by blocks 35. As indicated in Figure 2, blade members 31 are preferably inserted from the center of the assembly and are slid outwardly until they engage flange 33 of head 32, which restrains them from outward displacement in response to centrifugal force. Any suitable means may be employed to restrain blades 31 from sliding inwardly under the influence of gravity when the head is at rest, but we preferably employ frictional means which takes the form of flat leaf springs 3|, which seat in recesses 32 located in portions 38 of blades 31 and bear against the radial face of head 32. Springs-ll, as seen in Figures 1 and 4, bear upon a portion of the surface of runner-head 32 between plates 35. Since springs 4| are retained in recesses 42 the frictional contact thereof with runner-head 32 is suflicient to prevent undesirable sliding of blades 31.
Referring more particularly to Figures 2 and 4, blades 31 are provided with substantially flat abrasive-impelling surfaces 33. which extend from the outer ends of the blades to a point near the inner endsthereof. The inner ends of the blades are provided with curved impelling surfaces 34 for a purpose that will presently appear. As seen in Figure 1, the blades decrease in width toward their outer periphery in view of the fact that the velocity of the abrasive increases as it approaches the outer periphery of the blades, and in order to prevent the abrasive from escaping laterally from the blades we preferably provide blades 31 with ribs which are co-extensive with their impelling surfaces.
The abrasive may be fed into the center of the blade assembly by any suitable means, but I preferably employ for this purpose the following mechanism, described in detail and claimed in the above mentioned co-pending application.
To this end a stationary and substantially cylindrical abrasive distributing member 5|, supported in any suitable manner within the central space 52 formed between the inner ends 53 of blades 31, is provided. Abrasive is supplied to member 5| -by means of a cone member 55 se cured in place by any suitable means.
Cone 55 receives a spout member 51 through which abrasive is supplied to member 5|.
In view of the fact that rotation of head 32 causes blades 31 to function as a centrifugal fan, a high vacuum is developed within the member 5| and spout 51, with the result that any abrasive supplied to spout 51 will be drawn into member 5| and thence through aperture 55 to the blades. We preferably, however, provide head 32 with an auxiliary rotor or fan mechanism 59 for facilitating delivery of the abrasive through aperture58. Rotor or fan mechanism 53 is secured to shaft 25 by means of a cap screw 8|. Mechanism 53 is, preferably, assembled within member 5| in the manner described in co-pending application Serial No. 726,188, wherein the structure of members 5|, 55, 51 and 53 is tiescribed in detail.
While the present invention is disclosed in connection with the abrasive supply structure of the above mentioned co-pending application, it is to be understood that any other suitable delivery arrangement, such as, a spout delivering abrasive radially into the blades or axially of the axis of head 32 may be used without departing from the spirit of the present invention.
I Operation I The work is placed in registry with the discharge opening formed between housing members i3 and i5 and it is preferably mounted on a truck or conveyor or the like so that it may be moved around to expose various areas of it to the blast. Shaft 25 may be rotated at any desired speed, but we find that, with the machine illustrated, a speed of approximately 2400 revolutions per minute, in the direction indicated in Figure 2, is
suitable for satisfactory operation of the ma- I chine.
Sand or other abrasive is preferably allowed to drop by gravity into spout 51 and it is preferably supplied thereto in uniform quantities as by means of a screw or like conveyor operating at a predetermined constant speed. Rotation of head 32 causes blades 31 to establish a partial vacuum within member 55 and the interior of spout 51, so that the sand entering the spout is picked up by an air stream and enters rotor or fan mechanism 53.
Air and abrasive is accordingly supplied to the annular space deflned by member 5| and member 53, and it is uniformly withdrawn from member 5| through aperture 53 by the rotor or fan 53 and the suction effect of blades 31.
It should be observed, referring more particularly to Figure 2, that as the abrasive is discharged from aperture 53, it possesses angular as well as radial velocity in view of the impelling action of rotor 53. This initial velocity feature, when taken in connection with the fact that the inner ends of blades 31 are curved, operates to minimize any abrading action as blades 31 pick up the abrasive. In other words, the abrasive discharged from aperture 58 travels outwardly and angularly, and as the angular component of the velocity of an individual particle of abrasive is not greatly lower than the velocity of the inner portions of blades 31 that picks it up, and as these portions of blades 31 are curved, they strike the abrasive a "glancing blow and wear thereof under such action is minimized.
In view of the fact that the abrasive passing outwardly over blades 31 is increasingly accelerated until it leaves the blades, and it also possesses an angular velocity due to the rotation of the blades, it leaves them at an angle thereto. With reference to Figure 2, the velocity of the abrasive under discharge conditions is diagrammatically illustrated, wherein the radial or outward velocity is represented as Vi and the instantaneous angular velocity of the sand as it is about to leave the tip of the blade is represented as V2. These component velocities, when combined, result in a velocity VT and approximately represent the conditions existing in the machine during operation. It should be observed that as abrasive is delivered from only a small angular region of the rotor, which in the present case is below the axis of the members and through the openings between the housings i3 and I5, all of the abrasive is utilized for useful work, as no energy whatever is lost by abrasive being thrown against stationary housing l3.
Blades 31, during operation of the abrading machine are thrown outwardly under centrifugal force. This outward movement oi. blades 31 is, however, arrested when the blades engage flange 33. It will, accordingly, be clear that blades 31 cannot be thrown off of runner-head 32 since their radial movement is limited by flange 33 and any axial movement is resisted by the grooves formed between plates 35.
when runner head 32 is stopped the uppermost blades 31, tend to fall or slide toward the axis of therunner-head due to gravity. To prevent this movement of blades 31, which would position the blades so that an undesirable impact of the particular blades with flange 33 would take place, the present invention utilizes springs 4| which frictionally engage runner-head 32. As a consequence when blades 3.1 are placed in position and slid outwardly against flange 33, they cannot slide inwardly again due to the frictional engagement of the springs ll and runnerhead 32.
When it becomes necessary to replace blades 31, they may be slipped inwardly against the resistance of springs ll and removed and new blades substituted therefor. Wear element 2| may be readily replaced by removing housing ll.
The invention may be embodied in other speciflc forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.
What is claimed and desired to be secured by United States Letters Patent is:
1. In an abrading machine, in combination, a disc-like runner-head, a plurality of blades disposed substantially radially with respect to said head, means mounting said blades for guided sliding movement toward and away from the axis of said head, means for limiting outward movement of said blades, and leaf springs engaging a surface of said runner-head and said blades for resisting inward movement of said blades.
2. In an abrading apparatus, in combination, a disc-like runner head having a peripheral, axially extending flange; a plurality of sectorshaped plates, having inclined faces disposed in spaced relation on said disc within said flange. andwith their inclined faces disposed to form dove-tail grooves; means for securing said sector plates in place on said disc, and abrasive impeller blades having dove-tail formations thereon slidably connected to said disc through engagement with the walls of said dove-tail grooves, said flange providing an abutment for engaging one end of said blades to retain them against centrifugal force during operation of the abrading apparatus. f
3. The construction described in claim 2 abrading machine, comprising a body having an abrasive impelling surface, a dove-tail formation on one edgeof said body for slidingly securing said blade to the rotor of said machine, and I spaced shoulders formed by a recess in said dovetail formation and adapted to retain means therebetween for preventing inadvertent sliding of said blade.
5. In an abrading machine, in combination, a disc-like runner-head, a plurality of blades disposed substantially radially with respect to said runner-head, means mounting said blades for guided sliding movement toward and away from the axis of said head, means for limiting outward movement of said blades, and means for yieldingly resisting inward movement of said blades toward the axis of said head.
6. In an abrading machine, a disc-like runnerhead having a substantially flat face and adapted to rotate about an axis normally disposed to said face, a plurality of sector-shaped plates secured to said runner-head in engagement with said face, said plates being spaced from each other and having their neighboring surfaces so shaped as to define a plurality of outwardly extending guideways, a plurality of blades mounted in said guideways for sliding movement toward and away from the axis of rotation of said runner-head, and means for limiting outward movement of said blades in said guideways.
7. The abrading machine described in claim 6, wherein said runner-head is provided with a peripheral, axially directed flange in which said plates nest, and which assists in restraining them against outward movement in response to centrifugal force.
' 8. In an abrading machine, in combination, a disc-like runner-head, a plurality of blades disposed substantially radially with respect to said head, means mounting said blades for guided sliding movement toward and away from the axis of said head, means for limiting outward movement of said blades, and resilient means engaging a surface of said runner-head and said blades for yieldingly resisting inward movement of said blades.
WM. A. ROBENBERGER. WALTER. L. KEEFER.