US2858991A - Pulverizing plate - Google Patents

Description

Nov. 4, 1958 Y R, W L 2,858,991

' PULVERIZING PLATE Filed Dec. 5. 1957 J0 INVENTOR ATTORNEY 2,858,991 PULVERIZING PLATE Ralph G. Walsh, East 'Beuevme, Ontario, Canada, as signor to Deloro Sinelting 8; Refining Company, Limited, Deloro, Ontario, Canada a Application December 5, 1957, Serial No. 100,171

1 Claim. or. 241-296) 3 they make contact at their outer edges,one of.=such plates being stationary and the other being driven. Each plate, as conventionally employed is usually formed of metal and has a plurality of generally radially extending grooves and ridges on its concave face. The material to be pulverized is introduced through an opening in the center of the stationary plate. As the driven plate is rotated, the metal ridges on the inner sides of the plates within the lense like opening between the plates break, crush, and grind the friable or semi-friable materials fed to the unit. The size of the feed to the plates is reduced as it is forced by the revolving action of the driven plate toward the outer edges of the plates. Finally the feed reaches the extreme edge of the plates, where the plates actually contact; here pulverizing is completed and the powdered product drops from between the plates into a container.

The action of grinding and pulverizing is accomplished by the radial ridges on the face of the driven plate passing the radial ridges on the face of the stationary plate at high speed. Particles fed between plates of this design are reduced in size by the application of a series of blows struck in a scissor-like action by the driven plates radial ridges at the instant they are about to pass the radial ridges 'of the stationary plate. Such continued application of pressure for pulverizing applied in one direction only, prevents plates of radial design from performing with the efliciency of plates with parallel grooves and ridges. The scissor-like pulverizing action aided by centrifical action forces coarse and fine particles alike toward the outer circumference of the plates. Coarse particles are then cushioned by a bulk of fine particles and the accomplishment of pulverizing is slowed. The repetition of scissor-like action, always in identical direction tends to polish the plates, thus slowing the pulverizing speed of the radially grooved and ridged plates. It has been found that when hard metal alloys are used with radial grooves and ridges the polish becomes mirror-like and the pulverizing speed drops rapidly as the polish increases. To avoid polish soft metal is used in order that the hard particles being ground will partially imbed themselves into the metal so that the oncoming radial ridges will strike and crush the particles. Such scoring action lessens slippage and speeds the pulverizing action. It follows that where soft metal is employed to pulverize hard materials excessive wear will occur.

It is an object of this invention to provide a pulverizing plate the use of which permits any desirable increase in speed of grinding, reduces wear and scoring thereof, facilitates reconditioning, eliminates polishing thereof,

e I 2,858,991- lCe k P g d Ne s, 1958 and avoids contamination of materials under treatment. Another object isto provide a pulverizing plate which 7 may be manufactured from a wide variety of materials.

Another object is to provide a pulverizing plate which will permit closer regulation of the fineness of grind.

. A further object is to provide a pulverizing plate which is more economical in overall cost and maintenance.

To this end, the invention contemplates the provision of a grinding plate having on the grinding face thereof a single group of parallel ridges, such group occupying the major portion of said grinding face.

Other objects, details and advantages of the invention will become apparent-as this description proceeds with particular reference to .the accompanyingdrawing, in which, .A

Figure l is a plan view of a pulverizing plate in accordance with the invention,

Figures 2 and 3 areside elevations, partly in section, of the plate shown in Figure 1,

Figure 4 is a plan. view ofa slightly modified pulverizing plate in accordance with the invention, and Figures 5 and 6 are side elevations, partly in section,

I of the plate shown in Figure 4.

Referring to Figures 1, 2 and 3, 1 is a grinding plate of arcular or disc like form having a grinding face 2 and a rear face 3. The plate has the usual axial feed opening 4 which, as shown, is of gradually increasing diameter from face 3 to face 2, and the mounting bolt receiving sockets 5 in its rear face 3.

The grinding face 2 of the plate has a flat peripheral surface 6 of minor extent and a slightly dished or concave surface 7 of major extent extending therefrom. A plurality of parallel flutes or grooves 8 are formed in substantially uniformly spaced relation in the concave surface 7, each end of each groove 8 terminating at the peripheral surface 6. The end portions of each groove are curved gradually upwardly to the inner edge of the peripheral surface 6. The surface of each groove may be of arcuate cross section as shown. The depth of the grooves is substantially uniform. It will be apparent that the grooves form a plurality of alternate ridges 9 in concave surface 7.

Preferably, :as shown, the grooves 8 and ridges 9 extend in a direction at right angles to the center line or diameter of the plate that passes through the axes of the mounting sockets 5. It will be observed that the grooves and ridges, on each side of the parallel center line of the plate gradually decrease in length from such center line. It will also be observed that the feed opening 4 interrupts certain of the grooves and ridges.

The plate described is adapted to be employed as a stationary plate in a grinding machine in association with a revolving plate which, it will be understood, has a grinding face similar in all respects to that of plate 1 with the exception that, instead of the feed opening 4, the conventional complementary axial depression is formed therein.

It will be apparent that the number and dimensions of the grooves 8 may vary within wide limits. In the example illustrated, in a plate of eight inch diameter, 12 grooves of A3 inch depth maybe provided. The diameter of the concave surface 7 may be approximately 7% inches thus determining the length of the grooves which terminate on the periphery thereof.

Referring to Figures 4, 5 and 6, 10 is a pulverizing plate which is adapted to be used as the revolving plate in a grinding machine. It has a grinding face 11 and a rear face 12. The rear face 12 has a pair of mounting bolt receiving sockets 13. The grinding face has a fiat peripheral surface 14 of minor extent, a slightly dished or concave surface 15 of major extent extending therefrom, and an axial depression 16. A plurality of parallel flutesor grooves 17, with alternate ridges 18, are formed in the 'concave--surface-15-," eertain-of-grooves and"ridges being interrupted by the axial depression 16, as will be apparent. It will be appreciated that the general arrange- Use of pulverizing' platesasdescribed makes it possibletoincrease the speed of grinding merely by'increasing the number'of grooves'and" ridges on the plate. This is a simple manufacturing step since the grooves and ridges are parallel.

I rM-oreoven'use of parallel grooved andridgedpulverizing plates reduces metal wear; requiresless frequent and more simplified-reconditioning of the plates, and substantially eliminates -polishing as wellas scoring of the contact area at the 'edge of the--pl'ates.

Various materials, such as hard metal alloys, sintered the plates. Where iron containing material is being treated for assay purposes, plates of non-ferrous material may be used. I

Since scoring and'wear is reduced, salting of the sample under treatment by contamination with particles of the pulverizing plate isless likely with consequent avoidance of contamination.

"material, and the like, may be used for manufacture of 20 Since it is a simple matter to vary the number of "'groovesand'ridges in plates under manufacture, it is possible to supply plates in wide variety whereby fineness of grind can be more closely regulated.

Because of reduction in wear, overall cost of plates is reduced. Moreover, parallel grooved plates as described are more convenient and:t.hus.gmore economical to recondition.

I claim:

Atpulverizing, plate of circular form having a grinding face onone side.:thereof; said grinding face comprising a fiat peripheral annulan-surface of minor extent, and a concave surface occupying the remaining portion of said face; said concave'surface having a plurality of parallel grooves and ridges uniformly disposed upon the entire area thereof, each said groove and ridge having its ends terminating at said peripheral surface.

' References .Cited in thefile of this patent UNITED STATES PATENTS 111,636 .Ager Sept. 5, 1854 139,553 Dean June 3, 1876 749,630 Phipps Jan. 12, 1904 1,491,897 Blake Apr. 29, 1924 2,135,762 xNicholls Nov. 8,193?! 2,566,103 'Weston Aug. 28, 1951

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