US2314069A - Abrasive blast - Google Patents

Description

Patented Mar. 16, 1943 ABRASIVE BLAST Herbert T. Blount, Los Angeles, Ca'lii'., assignor to Mills-Alloys, Inc., Los Angeles, Calif., a corporation of Delaware Application May 31, 1938, Serial No. 210,916

8 Claims.

This invention relates to an abrading device of the type wherein the abrasive is in granular or shot form, which is discharged from a wheel against the article to be abraded by centrifugal force. due to rotation of the wheel at a high speed.

In general, such abrading devices have been proposed and used in the past. The revolving wheel is usually provided with passages extending from the axis toward the periphery, through which the shot or other abrasive passes as the wheel is rapidly rotated. The abrasive may be fed to the inner ends of these passages by any suitable feeding device.

The abrasive particles are often of the type that has high specific gravity, such as hard steel or other materials. Since they leave the wheel periphery at great speeds for producing the re-. quired hammering effect upon the work to. be cleaned or abraded, it hasbeen found that the wheel is itself very quickly abraded or worn away. The passages become enlarged and the form altered to such an extent as to impede the attainment of optimum inertia effects.

It is accordingly a commonly accepted detriment in this type of abrader that replacement of worn out wheels is required frequently; as often as after one or two hundred hours of service.

It is one of the objects of this invention to obviate these frequent renewals by materially increasing the length of useful life of the wheel.

This object is accomplished by lining the passages for the abrading material with a wear resisting layer; for example, tungsten carbide.

It is another object of this invention to make it possible touse the same wheel for an indefinite, extended life, by providing, renewable partsv in the form of nozzles, that are subject to the normal wear.

It is another object of this invention .so to; arrange the nozzles or passages that the wheel distributes the abrasive material in a band much wider than the width of the wheel, so as to operate upon a larger exposed area of the work to be cleaned or abraded. i

This invention possesses many other advan tages, and has other objects which may be made more easily apparent from a consideration of one embodiment of the invention. For this purpose there .is shown a form in the drawing accompanying and forming part of the present specification. This form will now bedescribed in detail, illustrating the general principles of the invention; but it is to be understood that this detaileddescription is not to be taken in a limiting sense, since the scope of this invention is best defined by the appended claims.

Referring to the drawing:

Figure 1 is an elevation of an abrading wheel, partly broken away; 7

Fig. 2 is a section on an enlarged scale as seen'on plane 2-2 of Fig. 1;

Fig. 3 is a fragmentary elevation of the outer end of one of the nozzles; and

Fig. 4 is a sectional view of an installation showing the wheel arranged for use.

The wheel 5 includes a frame or head 6 secured to a rotary shaft 1. This frame 6 provides a central space or cavity 8 for the reception of the abrasive material, and a plurality of renewable nozzle structures 9 extend outwardly from this spaceto the periphery of the wheel. With the wheel rotatin any material fed into space 8 will be discharged through the nozzles by centrifugal force. The rotation is usually so fast that its peripheral speed is high, of the order of 10,000 feet per minute; and the abrading material is dischargedthrough the nozzles 9 with great velocity.

The-wheel 5 is shown as supported for rotation'in the upper portion of a closed housing In (Fig. 4) This housing may be provided with a grate H some distance below the wheel, where the work to be abraded 0r cleaned is placed. The abrasive may be fed from any suitable source, as through a chute I2, discharging into a feeder I3. leading to the inner space 8 of wheel 5. This feeder l3 may include valving means, several forms of which are well known in the art, whichfeeds the abrasiveto the central space 8 over ,only a limited sector of the plane of revolution ofthe wheel. By this means the angle through which the discharge occurs is lim-- rials, depending on the work to be abraded.

Since any abrasive likely to be used is hard' enjough tocause rapid-wear of these wheels as usually constructed, they have an extremely short life.

' In the -present wheel, the parts which come in cont'actwith the abrasive while under high velocities, are lined with a hard, wear resistant material, such astung'sten carbide. Further,

sinceonly thea'dvancing part ofthe nozzle bore and I! for accommodating the edges of the rin'gs l8 and I9, and welding over the adjacent parts of the rings and plates as indicated at 38 (Fig. 2). One of the plates as 16, has'a cent'r'almachined and counterbored area into which is secured a hub 2|, as by cap screws 22; The hub 21 is" fastened in any suitable manner to shaft 1 to rotate therewith. The central space 8 is defined by ring I8 and plate 6, a central opening 2 3* in plate ll being provided for thefeeding mecha-- nism iii. The rin la is provided with a plurality of equi-distant bores or openings 24-; which may be midway between plates l-S- and IT, to receive the nozzle structures 9.

Each nozzle structure 9 consists of an inner member or lining 26 made'from some hard materialthat can resist wear, as tungsten carbide. The inner end 21 of the bore of the nozzle lining tapersoutwardly, while the outer end of the bore is provided with flattenedsurfaces 28 (Fig. 3) at right angles to the plane of revolution. This configuration ofthe bore gives a better distribution of the abrasive. The nozzle 26 has an outercylindrical jacket 29 of relatively soft metal, such as iron or steel, with its lower portion 30 of reduced diameter providing a shoulder 3|. This jacket strengthens and protects the brittle lining 26.

A protecting thimble 32' fits over the end ofthe jacket 29 and against shoulder Ring [9 is provided with bores 34, corresponding: to bores 24, each havingacounterbore 35" to receiveflange 33. These thimbles 32 maybe assembled on the ends of the nozzles 9' by being passed through any of the openings 39- (Fig. 1)' in plate H, after which they may be telescoped" over the nozzle and then the nozzle-may be inserted into aperture 34in ring W.-

This arrangement securely holds the nozzle structure against displacement by centrifugal force; clamping means, such asset screws 36, are provided, engaging the nozzles 9 and preventing them from moving inwardly into space 8. Thesescrews' also restrain the nozzles against rotation about their longitudianlaxis, so that, the flat sur-- faces 28 at the end of the nozzle may be accurately set and maintained. By loosening set screw 36, the nozzle may be turned. to bring another surface 28 in position when the first has; beenworn, or the nozzle may be removed and another one inserted.-

To protect the inner surface of ring I8 from wear by the abrasive, the area between the nozzles is covered by a: layer of resilient material 3], which may be soft rubber. To givea better distribut'ion of the abrasive over thegratell supporting the work, adjacent nozzles 9 are purposely inclined slightly in opposite directions from the plane of rotation.

As shown most clearly in Fig. 4, this arrangement has the effect of staggering the nozzle openings. shoot the abrasive particles farther toward the inclined direction; thus there is an effective spread of the abrasives m a direction" parallel" to" 7'5- Nozzlesthus staggered or inclined 'will' the axis of the wheel rotation, as indicated by lines 40.

What is claimed is:

1. A wheel of the character described including an inner ring, an outer ring, and front and back plates joining the rings, said back plate including means by which the wheel may be attached to a rotating support,.a plurality of nozzles extending from the space within the inner ring through said rings substantially to the periphery of the wheel, adjacent nozzles diverging in opposite directions from the plane of rotation passing through their inner ends.

2. In apparatus of the character described, a rotary frame having side flanges and radially spaced ririg's between the flanges, the rings being joined to the flanges, one or more nozzles supportedin said: spaced rings, said rings being providedwith alined apertures for the accommodation of said nozzles for supporting them, and a member telescoping; over one end of each nozzle and providing a-flange to-prevent removal of said nozzle through the corresponding aperture.

3. A wheel of th'e'ch'etrac'ter described including an inner ring, an outer ring, and means joining. said rings, the inner ring defining a space adapted to receive abrasive material, means forming a tubular nozzleextendingfrom saidspace through the rings for discharging the abrasive. means forming, a shoulder on the-nozzle engaging. one of? said rings to restrain the nozzle against centrif ug'al'force due to-rotation of'the wheel-,andmeans adapted to clamp the nozzle in the wheel, saidnozzle being so arranged that; upon loosening;

-- said clamping means, th nozzle may be turned about its axis to cause a different part of its bore to be in contact with the abrasive as the abrasive is' discharged.

4.-In av device of the character described,- a rotary frame, a plurality of nozzle structures supported by the frame and angularly spaced fromeach' other about the frame axis-and means detachably securing said nozzle structures in the frame, said means permitting the nozzle structures to be adjusted angularly' about their axes, respectively without altering their positions in a radial direction, to bring different areas of the nozzle passages into contact with the discharged: abrasive, and operating to secure said structures in any adjusted position.

5. In a deviceof' the character described, a rotary frame, meansforming a nozzle structure and having a shoulder uponsaid structure is supported in the frame, and meansto detachably secure said" structure onsaid shoulder in said wheel including arim through which the nozzle extends, said nozzle includinga lining of hard material and a reenforcing' jacketof softer material, and a thimble of harder material thanthe jacket, s'aid' thimble being secured (in-the jacket and having ashoul'd'er adapted to engage the rim and retain the nozzle in the wheel, as well as a skirt to protect thatportion of the jacket outside the rim. 7

s 7. In a device for imparting motion to divided material, a rotary frame; and a; series of nozzle" structures detachably supported on the frame 8. In a device for imparting motion to divided 10 material, a rotary frame, and a series of nozzle structures detachably supported on the frame and angularly spaced about the axis of the frame, said nozzle structures being of such length as to direct the discharge of said material, the inner ends of said nozzles being located in a common plane normal to said axis, adjacent nozzles diverging in the direction of said axis, to increase the area over which the material is discharged.

HERBERT T. BLOUNT.

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