US3517461A - Abrading apparatus - Google Patents

Description

June 30, 1970 a. E. BALDWIN- ETAI- 7,

ABRADING APPARATUS Filed March 21, 1968 a Sheets- Sheet 1 Fig. I G

1 N VEN '1 URS. BRIAN E. BALDWIN 34 BY HERBERT E.KARL|NSKI PRESSURIZED AiR ATTORNEY.

June 30, 1970 B. EJ'BALDWIN ETAL 3,517,461

Asxmm AP'PARATUS Filed March 21, 1968 a Sheets-Sheet 2 IN VEN'TOR S.

BRIAN E. BALDWIN HERBERT E.KARLINSKI ATTOR NEY.

United States Patent O 3,517,461 ABRADING APPARATUS Brian E. Baldwin, Wilmette, and Herbert E. Karlinski,

Chicago, 11]., assignors to Pennwalt Corporation, a corporation of Pennsylvania Filed Mar. 21, 1968, Ser. No. 714,945

Int. Cl. B24c 3/00 US. Cl. 51-42 10 Claims ABSTRACT OF THE DISCLOSURE The abrading apparatus includes a pressure vessel which houses a storage reservoir and a distributor for abrasive material. The vessel has an inlet for pressurized gas and a plurality of outlets for gas-borne abrasive material, the distributor being angularly movable about an upright axis to distribute the abrasive material from ananularly spaced locations through the outlets and preferably being reciprocated in an inclined arcuate path by a rotary vibrator. Provision is made to signal when the pressure vessel is not locked shut and also when the storage reservoir is almost depleted of abrasive material.

This invention relates to abrading apparatus of the type which might be employed for trimming, cutting, cleaning or deburring articles of manufacture.

Apparatus of the type set forth is shown, for example, in US. Pat. No. 2,696,049 to Black and also US. Pat. No. 3,344,524, issued Oct. 3, 1967, in the name of Walter Kulischenko and assigned to the assignee of the present invention.

One of the limitations of otherwise satisfactory abrading apparatus is the ability to supply gas-borne abrasive material from a central source in uniform concentrations to several nozzles over an extended period of time. To do this requires apparatus capable of storing a large amount of abrasive material and of equally distributing the same therefrom in the same ratio to duplicate gas streams flowing through a number of supply lines, all to the end of continuously achieving like cutting action by all nozzles. This permits a particular abrading operation to be carried out simultaneosuly at a number of adjacent work station, for example on a number of parallel assembly lines, with uniform results.

Apparatus for carrying out the present invention supplies nozzles with gas-borne abrasive material from a pressure vessel which is fed with pressurized gas and which houses an abrasive distributor and a reservoir for replenishing the supply of material in the distributor. According to the present invention, the distributor is angularly movable about an upright axis and is provided with outlets at spaced locations about the axis through which the abrasive material is distributed. Preferably the outlets in the distributor are arranged to extend tangentially to the annular wall, the latter being formed about the axis of movement of the distributor.

It is also preferred that the distributor be moved an gularly by a suitable drive so as to reciprocate, with the distributor lifting and rotating the material in one arcuate direction on a distribution stroke and moving in opposite direction to original position on a return stroke.

Provisions are made for a single to be given when abrasive material in the storage reservoir is reduced to a low level, also for signalling when the separable parts of the pressure vessel are unlocked and for closing off the pressurized gas supply, for heating the pressurized gas supply, and for keeping the distribution outlets clear of accumulations of abrasive material.

These and other objects, features and advantages of the invention will appear more fully from the detailed Patented June 30, 1970 description which follows, taken in connection with the accompanying drawings forming a part of the present application and in which:

FIG. 1 is a vertical sectional view of apparatus embodying the invention, taken along line 1-1 of FIG. 2, and

FIG. 2 is a horizontal sectional view of the same apparatus, taken along line 22 of FIG. 1.

The abrading apparatus shown in the drawings comprises a pressure vessel 10 including a generally fiat base 12 supporting a dome or bell-shaped shell 14 of circular cross section. The latter is provided with a lifting ring 16 which may be employed when moving the assembled vessel 10 and when separating or reuniting the shell 14 and base 12. Inside the vessel 10, a storage reservoir 18 for abrasive material is supported in elevated position by a stand 20 in position to feed or replenish an abrasive distributor 22 therebelow by gravity as the contents of the distributor are metered and fed through a funnel entrance 23 of outlet lines 24 leading to nozzles. One source nozzle is shown in FIG. 1 and designated by the numeral 21. The abrasive material is carried through the lines 24 by streams of air or any other desired gas brought into the vesel 10 under pressure via inlet 26 in the base 12. As best seen in FIG. 1 the outlet lines 24 each have a downstream portion comprising flexible tubes 25 joined to the base 12 by a threaded fitting 27.

The apparatus of the present invention is preferably employed for abrading with alumina or beaded glass powder, although the invention may be practiced while using any suitable finely divided or particulate hard material. It is recommended, however, that highly hydroscopic materials be avoided in order to minimize the plugging of flow passages and the encrusting of component parts. Hygroscopic water can be eliminated by preheating the abrasive materials to above 212 F., and by delivering a dry carrier gas to the vessel 10. Still another consideration is corrosion; and therefore non-corrosive abrasives are preferred as the working material and stainless steel is the material of choice for the apparatus, especially for those components contacted directly by the abrasive material.

Briefly stated, the abrading operation is carried out by impinging a high velocity stream of airborne or gasborne abrasive particles on the surface being abraded. Such stream is provided by introducing the abrasive material into the gas stream as it flows through the vessel 10 between the inlet 26 and the outlet lines 24, the proportion of material to gas being maintained constant in order to ensure uniform abrading action. With uniform abrading action it is possible to control the extent of abrasion efiected on a given workpiece by precisely timing the exposure of the workpiece to the stream.

-In order to provide the high velocity stream as aforesaid, an air compressor (not shown) may serve as a source of air pressurized in the order of between 225 and 250 p.s.i. for delivery to the vessel 10. Gases other than air may also be employed in carrying out the invention. In addition, low pressures such as p.s.i. may be employed for carrying alumina particles with approximately the same cutting effect as glass bead particles carried by air at 225 p.s.i. Thus, air pressure may be varied in relation to the desired cutting action; and it is conveyed from the source by an inlet supply pipe 28 connected by a fitting 30 to a threaded portion of the inlet 26 in base 12. A baffle 32 serves to disperse the incoming air and thus prevent scattering of abrasive particles onto moving mechanical parts. A suitable heater 34, of the electrical type for example, may be installed on the pipe 28 to preheat the pressurized air to about F. in the interest of lowering its relative humidity. Flow through the inlet supply pipe may be controlled by a manually operable valve 35.

The shell 14 is secured to the base 12 in fluid tight relationship by means of a rotary bayonet lock comprising irrterlocking inner and outer rings 36 and 38 secured respectively to the rim of the shell and to the upper surface of the base. The rings 36 and 38 have sinuate margins overlapping one another in opposite radial directions whereby the crests 40 of the inner ring 36 will register with the depressions 42 in the outer ring 38 in the unlocked position of these parts but otherwise the crests 44 of the outer ring will register with and overlap the crests 40 of the inner ring 36, as in the locked position shown in FIG. 2.

In order to limit relative rotational movement of the rings 36 and 38 when locking the assembly, a pair of stop pins 46 are spaced 180 apart in the arrangement, as best seen in FIG. 2, to provide an abutment in the path of portions of the inner ring 36. Opening movement involves counterclockwise movement of the inner ring 36 and shell 14, as viewed in FIG. 2.

A handle 48 is secured to the inner ring 36 to facilitate rotational movement of the inner ring and shell assembly relative to the outer ring 38 and base 12 assembly, as during locking and unlocking of these assemblies to one another.

When the vessel assembly is locked as aforesaid an electromagnetically operable dump valve 50 in inlet supply pipe 28 is held closed to the atmosphere by energization from electric current flowing through a closed microswitch 52 mounted on the outer ring 38 and arranged to be held closed through engagement of its plunger by a finger 54 mounted on the inner ring 36, as shown in both views. In unlocked position of the vessel parts the finger 54 will disengage the plunger of microswitch 52 and deenergization of the dump valve 50 opens the inlet supply pipe 28 to atmosphere, thus preventing pressurization of the vessel when the shell 14 is not sealed to the base 12.

There will now be described a device for signalling, or actuating another component, when the supply of abrasive powder in the reservoir 18 is reduced to a predetermined level or depleted. The stand 20 is comprised of upright tubular legs 56, preferably four in number, which are braced by upper and lower rings 58 and 60. The upper ends of the legs 56 are arranged to support the trunco conically shaped lower wall 62, below the annular outer wall 63 of the reservoir 18, through upwardly biased plungers 64. Each plunger 64 is slidably received in an upper portion of its associated leg 56 and biased upwardly by a compression spring 66 compressed against a [firmly held plug 68 or other form of abutment surface. The springs 66 are selected to have suitable resilience or spring constant to elevate the reservoir 18 as the supply of abrasive material in the reservoir is reduced, thereby releasing the upwardly biased switch handle 70 of a normally closed switch 72 to close the electrical circuit through a warning lamp 14 when the reservoir 18 is nearly empty. Obviously, the means responsive to upward movement of the reservoir just described may be employed for actuating or deactuating electrically responsive devices other than lamp 74, or in addition to lamp 74, if so desired.

The distributor 22 for abrasive material is disposed within the pressure vessel and comprises a bowl 76, or other suitable container preferably open at the top, and mounted for angular movement about an upright axis on a driving mechanism 78. The bowl 76 may be secured to the driving mechanism 78 by a bolt or other suitable means. The bowl 76 is provided with outlet means in the form of tubes 80 disposed horizontally and tangent to the annular bowl wall. The bottom wall '82 of the bowl 76 is downwardly sloping as it extends outwardly of center, thus directing the flow of abrasive material toward the outlet tubes 80. The outer ends of the tubes 80 are positioned above the respective mouths of the funnel entrances 23 to the outlet lines 24.

With the foregoing arrangement of the outlet tubes 80 and the funnel entrances 23 of lines 24 it should now be apparent that it is advantageous to limit the angular motion of the bowl 76 by the driving mechanism 78. Preferably, in this regard, the extent of arcuate movement of the outer ends of the tubes is no greater than the are distance along the path of such movement across the top of the funnel entrance 23. This provision minimizes spillage of abrasive material and effectively delivers a free flowing supply of such material into the mouths of the lines 24, while at the same time admitting air or gas for flow therethrough as a carrier stream.

The driving mechanism 78 is suitably a so-called Syntron rotary vibrator which reciprocates the bowl 76 in an inclined arcuate path about the axis of movement. Thus driven, the bowl 76 is lifted and turned in one direction of movement, so as to increase the normal force between the bottom wall 82 and the abrasive material. Abrasive material is thereby dispatched in a tangential path through the tubes 80. On the return or reverse stroke the bowl '76 is oppositely driven by the mechanism 78 to the same limited arcuate extent back to original position, but this declining arcuate path of movement is with reduced normal force and therefore with little or no driving effect on abrasive particles.

Optionally, the passageway, within each outlet tube may be kept clear, that is, free of accumulated abrasive material, by installing a loose wire member 84 therein which vibrates in response to motion of the distributor 22. Only one such wire 84 is shown in FIG. 2 for the sake of clarity, but each tube 80 can be so equipped if desired. The diameter of the wire member 84 can also be selectively adjusted to produce the desired amount of flow through its associated tube 80. Obviously, the flow area through a given tube 80 is reduced with a larger wire member 84 and vice versa. This feature can likewise be employed to adjust the relative flow rates of the abrasive streams leaving bowl 76. Moreover, by keeping the tubes 80 clear there is instant starting of the abrasive streams after shut down of the apparatus. By bending the ends of member 84 it will be held in position during operation, as illustrated.

During start-up it may be desired to introduce air to the pressure vessel at a slow rate until the desired pressure is reached. Suitably, this can be accomplished by providing a restricted conduit 86, for example A diameter conduit as compared with 1" diameter conduit for inlet pipe 28, to bypass the valve 35; and a flow valve 88 as further required to control flow through the bypass con- What is claimed is:

1. Abrading apparatus comprising:

nozzle means,

a source of pressurized gas,

a pressure vessel including a base and wall structure defining a shell,

a storage reservoir for abrasive material disposed within said vessel,

means for supporting said reservoir,

a distributor for abrasive material disposed within said vessel and comprising a container for abrasive material, said container being mounted for angular movement about an upright axis and being provided with outlet means at spaced locations about said axis,

means for conveying abrasive material from said storage reservoir to said container for replenishing the supply of abrasive material therein,

means for driving said distributor angularly about said axis to discharge abrasive material from said container through said outlet means,

first conduit means connected between said pressurized gas source and said vessel for delivering gas to said vessel and pressurizing the interior thereof,

and second conduit means connected between said nozzle means and said vessel and having inlet means for the respective outlet means of said distributor arranged adjacent thereto for receiving abrasive material from said distributor and gas from said vessel and for conveying gas-borne abrasive material to said nozzle means.

2. Abrading apparatus according to claim 1 wherein said container is a bowl with annular wall structure formed about said axis, and said outlet means comprises at least one tubular member extending generally tangentially to said annular wall structure.

3. Abrading apparatus according to claim 1 wherein said driving means comprises a rotary vibrator, a driving member connecting said container to said vibrator, and means guiding said driving member for movement in an inclined arcuate path about said upright axis, whereby said container receives reciprocating drive impulses which lifts and throws said abrasive material out said outlet means in one direction of arcuate movement and returns to original position after arcuate movement in opposite direction.

4. Abrading apparatus according to claim 1 wherein the supporting means for said reservoir includes resilient structure biasing said reservoir upwardly against the weight of abrasive material stored therein, and further including means responsive to upward movement of said reservoir to a predetermined position as the supply of abrasive material is being depleted for signalling such condition.

5. Apparatus according to claim 1 wherein said base and said wall structure are separable to provide access to the interior of said vessel, and further including sealing means and a rotary lock between said base and the bottom of said wall structure, and switch means responsive to movement of said wall structure to locked and unlocked positions relative to said base for signalling when said Wall structure is not locked to said base.

6. Abrading apparatus according to claim 5 further including a normally open valve in said first conduit means responsive to signalling by said switch means for closing said first conduit means when said wall structure is not locked to said base.

7. Apparatus according to claim 1 wherein said container includes annular wall structure formed about said axis, said outlet means comprises a plurality of tubular members extending generally horizontally and generally tangentially to said annular wall structure, said driving means includes a rotary vibrator for reciprocating said container in an inclined arcuate path about said axis, and the respective inlet means of said second conduit means define openings positioned below the outer ends of said tubular members to receive abrasive material discharged therefrom for mixture with pressurized gas and conveyance thereby to the respective nozzle means.

8. Abrading apparatus according to claim 2, further including a wire element loosely disposed in said tubular member and extending therethrough to maintain said tubular member free of deposited abrasive material by movement therein in response to angular movement of said container.

9. Abrading apparatus according to claim 7 wherein the extent of arcuate movement by the outer ends of said tubular members in one direction is no greater than the arc distance along said path across the opening defined by said inlet means.

10. Abrading apparatus according to claim 1 further including selectively operable means for heating the gas flowing through said first conduit means.

References Cited UNITED STATES PATENTS 2,696,049 12/1954 Black 51-12 X 2,919,517 1/1960 Hestad et al. 51-8 3,344,524 10/ 1967 Kulischenko 51l2 X LESTER M. SWINGLE, Primary Examiner

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