US2474305A - Beater element for pulverizing apparatus - Google Patents

Description

0. CRAIG BEATER ELEMENT FOR PULVERIZING APPARATUS June 28, 1949.

Filed April 6, 1945 2 Sheets-Sheet l 0- CRAIG BEA'I'ER ELEMENT FOR PULVERIZING APPARATUS Filed April 6, 1945 June 28, 1949.

2 Sheets-Sheet 2 grvuq/wfm OLLlso/v CRAIG Patented June 28, 1949 BEATER ELEMENT FOR PULVERIZIN G APPARATUS Ollison Craig, Worcester, Mass,

Stoker Corporation,

Worcester, Mass,

ration of Massachusetts Application April 6, 1945, Serial No. 586,943

2 Claims.

This invention relates to beater elements for pulverizing apparatus, and more particularly to the construction of an improved beater element adapted to be mounted upon the rotor of a highspeed pulverizer and to break up the incoming coarse material into fine particles.

It is one object of the invention to provide a beater element which is capable of operating in a highly satisfactory manner throughout a long life of useful service.

It is a further object of the invention to provide a beater element so constructed that the wear thereon will take place in a uniform manner.

It is a further object of the invention to provide a beater element so constructed that concentrated wear on the walls of the pulverizing chamber will be avoided.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawing illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. 1 is a vertical section through a pulverizing apparatus having my improved beater elements installed therein, the section being taken on the line II of Fig. 2;

Fig. 2 is a section taken on the line 2-2 of Fig. 1;

Fig. 3 is an enlargement of a portion of Fig. 1;

and

Fig. 4 is a perspective view of one beater element removed from the pulverizer.

The pulverizing apparatus illustrated comprises a hollow casing shaped to provide a pulverizing chamber I and a fan chamber II connected by a central passage I2 which forms an outlet for the pulverizing chamber. An inlet chute I4 is'provided to introduce coarse material into the pulverizing chamber ID at the side opposite the outlet I2. The fan chamber is of scroll form and provided with a tangential outlet passage I5. A tramp metal pocket I6 is located at the bottom of the pulverizing chamber, this pocket being closed by a removable sliding plate I1. A horizontal shaft I9 extends centrally through the casing and is rotatably supported in suitable bearings 20 located outside the casing. A vertical disk 22 is mounted on the shaft within the pulverizing chamber to divide the said chamber into a crushing zone 23 at the inlet side and a grinding zone 24 at the outlet side, these two zones communicating around the periphery of assignor to Riley a corpothe disk. On the inlet side of the disk there are mounted beater elements 26 which will be subsequently described in detail, as they form the subject matter of the present invention. On the outlet side of the disk there are mounted beater elements 21 which cooperate with stationary pegs 28 supported on the casing wall. Rejector blades 30 are mounted on the shaft adjacent to the outlet passage I2, and a fan 3I is mounted on the shaft within the fan chamber II. The pulverizing chamber ID is provided with a peripheral liner plate 32. Except for the beater elements 26, the various parts as described so far may be similar to those disclosed in my prior Patent N 0. 1,714,080 granted May 21, 1929.

Referring now to Figs. 3 and 4, it will be seen that each of the beater elements 26 comprises a flat plate 33 shaped as a circular ring sector. These plates are mounted closely adjacent to each other on the peripheral portion of the rotor disk 22, and they provide a covering which protects the disk from wear. On the back of each plate there is provided a cylindrical projection 34 which enters a similarly shaped hole in the disk 22 to locate the plate in its proper position. The plates are formed with countersunk openings 35 to receive the heads of bolts 36 which hold the plates against the rotor disk. On the exposed face of each plate there is provided a fiat substantially rectangular blade 38 which lies approximately in a radial plane near one side of the plate. This blade 38 is preferably cast integral with the plate and so shaped and located as to avoid interference with the bolt openings 35. The blade 38 is of appreciable width and extends throughout substantially the entire length of the plate 33 (measured radially) which is considerably greater than the width of the blade, so that the front or advancing face of the blade provides a large area for contact with the material which is to be pulverized.

The coarse material is admitted through the chute I4 to the interior of the circle formed by the revolving blades 38. Because of the direction of the air currents and of the initial velocity of the entering material, the material tends to travel outwardly between the blades and close to the plates 33. This has a decided tendency to concentrate the wear on the blades in the region close to the plates, and to concentrate the wear on the peripheral liner plate 32 in the region located in line with the exposed faces of the plates 33. This wear concentration is undesirable, as it greatly shortens the useful life of the parts. In order to avoid this difilculty, the front face of each blade 38 is provided with a series of generally parallel ribs 39 which extend across the blade in directions approximately perpendicular to the plate 33, and hence across radial lines. These ribs taper in thickness, with their greatest thickness at their junction with the plate 33. Preferably the inner surface 40 0f each rib,-i. e. the surface nearest the axis of the-machine, is inclined gradually outwardly in a direction away from the plate 33. Consequently this surface 40 lies at an obtuse angle with the plate, andasthemateriah travels outwardly over the front face of' the" blade these inclined surfaces will deflect the material away from the plateiand distribute it-substantially uniformly over the-blade; Asa result,- the wear on the blade will be uniform, and the wear on the peripheral liner 32 of thelpulverizing chamber will be far less concentrated than with prior constructions, greatly prolonging the Ii'fe'of will increase theimpact'efiect, produce more effective reduction of the material, arrdjdecrease thewear on thebladesby erosion. .At'the same time the inclined inner surfaces 40. of theribs will deflect the materialaway from the plates 33' and provide a much more uniform distribution of: the wear on the blades. Upon leaving. the .blades the material will strike'the peripherallinin'g32 of t'he'pu-lverizing chamber and then flow around the periphery of the disk 22:11nder the influence of the air'current produced-by the blades and by thefan 3|. In the pulverizing zone the material will :be reduced to a fine powder bythe action of the revolving pegs 21 and thestation'ary pegs 28-, 'whereupon'the finernaterial will. escape through the central passage l2 to'the fan chamber H. Coarse particles approachingthis passage will be returned by the rejector. blades 30 to the pulverizing zone. The fine particles 'will bedischarged from the fan chamber in suspension in the" air currentthrough the outletpassagel5;

Thebeater elements 26 will have a far longer useful life than previouslyknown constructions,

.4 and. they will greatly increase the life of the liner plate 32. These beater elements, with the tapered ribs 39, are well adapted for manufacture by casting in accordance with known foundry practice.

Having thus described my invention, what I claim as: new and desire to secure by Letters Patent is:

1. A beater element for a pulverizing apparatus comprising a rotor wear plate shaped as a circular:ringz sector and having openings therein to facilitate its attachment to a rotor disk, a substantially rectangular flat blade integral with the plateand' extending in an approximately radial pl anefrom one: face of the plate, the length of th'ebladeimeasured radially) being considerably greaterrthanits-width, and a series of generally parallel ribs extending from the plate and across thefront surface of the blade in directions approximately perpendicular to the plate, the ribs havinginner surfaces'which lie at obtuse angles with the-plate.

v2. .A'beater elementfor a pul-verizing apparatus comprisingta rotor wearplataa blade extending from one :face of the" plate'and lying approximately in a radial-plane, and a series of ribs extending from the plate and across the front surfaeezofstlre blade, the ribs tapering in thickness, with their greatest thickness at their junction with the plate, the ribs having inner-surfaces wlnichiare. inclinedgradually outward-1y in a direction away from the plate.

OLLISON CRAIG.

REFERENCES CKTED The following references are of record in the file of this patent:

UNITED.- STATES- PATLN I'S Italy J arr. 28,1931

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