US1295291A - Grinding-mill. - Google Patents

Description

J.-S. FASTING GRINDING MILL.

APllCATlON FILED APR.4. 1917.

1,295,291. Patented Feb. 25, 1919. 7

WITNESS IN l/E/V 70/? warren sra'rns Parana onnr on.

JOHAN S. FASTING, 0F FREDERIKSBERG, NEAR COPENHAGEN, DENMARK, ASSIGNOR T0 F. L. SMIDTH & 00., OF NEW YORK, N. Y., A CORPORATIONOF NEW JERSEY.

GRINDING-MILL.

Specification of Letters Patent.

Patented Feb. 25, 1919.

Application filed April 4, 1917. Serial N o. 159,822.

To all whom it may concern:

Be it known that I, JoHAN S. FASTING, a subject of the King of Denmark, residing at Frederiksberg, near Copenhagen, Denmark, have invented certain new and useful Improvements in Grinding-Mills, of which the following is a specification, reference being had to the accompanying drawings, forming a part hereof.

This invention relates to the construction of partitions for use in grinding mills and has for its principal object to provide partitions which shall serve their intended purpose and, in addition, shall be of such character as to have a positive conveying action on the material, as to cause it to travel longitudinally through the mill. In accordance with the invention the openings in the improved partitions or rings have surfaces so inclined with relation to one another and to the material that they will lift the material positively and discharge it in such manner as to bring about a positive conveying action thereof, for any given direction ofrotation of the mill. Partitions or rings of this sort, of course, will positively prevent, or at least materially retard, the movement of the material through the mill when the mill is rotated in the reverse direction; The present invention is further concerned with the provision of partitions or rings having openings therethrough so formed as to afford a screening action for the material during its movement through the openings. This screening action is secured in accord ance with the invention by forming the screening openings of the proper size. A further object of the invention is to construct the screening openings in such a manner as to protect the openings from injury through blows of the grinding bodies and material thereon. This object is achieved by forming the openings adjacent the mid-section of each partition or ring so that the grinding bodies and material can not fall directly against the openings and subject their peripheries to the hammering or peening action which would otherwise occur. Still a further object is to'provide a screening partitionlof the general character described which may be cast readily without danger of burning the cores by providing heavy cores which pass part way through the partition from the opposite faces thereof and are ofi'set in such a manner that they overlap only where the slot is formed. Cores of this character, as will be understood, are not liable to be burned and so permit'screening openings of relatively small size to be cast readily. Further objects of the invention will appear hereinafter in connection with the detailed description of the accompanying drawings, in which- Figure 1 is a fragmentary detail view in cross-section of a grinding mill illustrating one form of the partition rings.

Fig. 2 is a detail view through portions of two ring sections shown in Fig. 1.

Fig. 3 is a sectional View of a somewhat modified form of ring section constructed in accordance with the invention.

As shown in Fig. 1, the partition is formed in separate sections which are slightly separated from each other at their ends, are supported against the outer wall of the mill a, or its lining a, and are detachably secured to the drum so as to be capable ofeasy removal and replacement. Each section is formed with a foot I) adapted to rest in a step c placed therefor in the lining, and two adjacent sections are secured together to the outer wall of the mill by a common bolt d, the head of which engages shoulders formed. on thepartition or ring sections, while the outer end receives a nut outside of the shell a. In this construction the inner edges of the ring sections are held firmly in alinement by wedges e engaging grooves 72 in adjacent ends of adjacent sections and provided with threaded portions 6 to receive nuts 6 by which the wedges are drawn firmly into place. In so far as the form, character, relative disposition and means of mounting the several sections of each partition g0, changesmay be made through wide It is the purpose of this application to cover, in principle, the speoifio'type' of partition or ring shown in cross-sectional form in the drawings. Each of the rings herein illustrated shows that while free longitudif nal movement of the material is permitted by the openings formed therein, this movement may be actually accelerated, and made positive in character, by the inclusion of sunfaces adjoining the openings in the ribs which shall lift the material with a sort-of shovel action and discharge it in such direction as to constantly impel it through the mill for any given direction of rotation of the mill. It will appear further that this shovel action is dependent upon the direction of rotation ofthemill and that if such direction be reversed, the improved rings or partitions willeither prevent the passage of the material or at least will seriously retard it.

As shown in'liig. 2, each ringsection is formed with radial openings f'between which arebars g which are beveled on oppositesides as; clearly shown. The openings and bars on opposite sides of the ring'sections do not'regist'er exactly but are offset with respect to eachother'so that the central passage f through which the corresponding reversely tapered openings 7 communicate, is of much less width'than said openings. Theprimary effect'of such offsetting ofthe openingsand bars is to give them a somewhat shovel-like action on the material either assisting the'passage' of the material through the rings or retarding it, according to the direction of'movement of the ring sections'with respect to "the line of movement of the material through the drum. Thus with the ring sectionsmo'ving in the direction indicated by thehor'izontal arrowin Fig. Qand' the material moving through the drum indicated by the vertical arrow; the rings would have a shov'elaction'inopposition to the direction of movement of the material and would: therefore retard the movement of the l'naterial somewhat, while if the-directionof movement of'the'rings' were reversed the shovel'a'cti'on of the rings would assist the movement "of" the material. This has been shown to be afact by actual operation of a mill equipped with such rings.

Anotherfeature of importance're'alized by the improved construction herein shown, lies in the peculiar formation of the screening cpenings f proper by which thematerial in its 'lengitudinal movement is constantly screened. These cpe ings f, 'it will be "observed, are formed atabo'ut the mid-section e'ft-herin'gs and an appreciable distance from theopposite' faces thereo'f'so' that they cannot" be" subjected to'the direct hammerlihe blows of the'falling material and grind mg bodies. Indeed, it will 'be'proper to make the cpeniirgs f ccf suchuimensione that the grinding 'bo'dies'ca-ir nevercome into direct engagement with the central 'scr'eening cpemngsf. At all events, by 'the'constructron described", the life of each ri'ng isma terially increased by'the protection thus af= forded to the screeningopenings.

In I Fig. 3 the ring section is" made up" in much "the manner described in connection with the form shown in Fig. 2 in that each ring section'is made up of a series of radially extendlng bars G between'which are formed openings F on the opposite'side edges of the bars adjacent the mid-section of the rings. In this embodiment, the rings instead of having their edges beveled have them formed straight, that is-,at right angles to the direction of-movement of the ring. The inclined sides G of -thfle bars G effect the desired conveying and these beveled sides are so related to one/another and to the rings that-when the mill is rotated in one direction the beveled: sides of one face of'each'of the rings will come into play to convey the material through the mill inone direction,-while when the mill isrotated in the opposite direction the-other beveled sides G onthe other side faces (if-the; rings-will cause the material to travel in the opposite direction. 7 "This be-desirable under some conditions of use. Thisem'bodiment retains the screening-action described in. connection with the form shoWninFig'xQ and embracesall of the advantages of the improved screening openings;

It will be observed, upon examination of thedrawing, that the shoveling action of, the rings or partitions-and the. protection of the communicating openings from hammering by the grinding bodies,-are -brought about by the formatiorr'of the radially extended openings or recesses Y in opposite faces of the partition,- which recesses communicate through -a narrower radial-f space -at one sideof the bottom'of each recess, while the two communicating recesses areoifset from each other in a circumferential direction,--atleast one side ofeaehuecess, as shown'inFig. 3, or bOth'sides, as shown iii-Fig. 2, being beveled away from the communicating opening.

The embodimentsherein shown while intendedto be merely,- illustrative of; suitable partitions orringst for-practising the invention and obtaining that conveying; action in association with the shoveling action, which constitutes the invention, serve to show clearly that by changing the general crosssectionaloutlines' of the rings, 1 any' desired action of the surfaces on thecharge-may be obtained. By this is meant that rings may be formed to conveythe material in. one direction for-a given direction of rotationof the mill, while preventingz the-movement of the mater'ial inthe opposite direction upon the reversal -of the direction "of rotation or,

the cross-sectional outline of,the rings may V V the mill; or," in the remaining condition, may

be formed to positively convey the material with equal facility in either direction depending upon the direction of rotation. As suggested, these conditions may be realized by casting the partition in the desired form. The improved partitions or rings may be found of especial advantage for use in combination mills in which grinding bodies of one character are held in one grinding chamber, while grinding bodies of a dissimilar character are held in another chamber to which the material passes from the first named chamber. Under such conditions of use, the openings through the improved rings would necessarily be smaller than the grinding bodies so as to prevent the passage of the grinding bodies therethrough. A manufacturing consideration of importance which has not been referred to hereinbefore and which applies to all of the forms shown, resides in the facility with which the improved partitions may be cast. It is obvi ously diificult for the screening openings to be cast in partition plates since the cores of such openings are necessarily small and liable to be burned by the heat from the molten metal. The improved construction, however, permits the screening openings to be formed without the provision of special cores therefor since the openings at the opposite faces of the plates are cast with relatively heavy cores and these cores may be so arranged with relation to one another and overlapped, as to insure the formation of the desired screening opening at the intended place.

I claim as my invention:

1. In a grinding mill, the combination of a rotary shell or drum, a transverse radial partition, and means to secure said partition in place, said partition having openings extended each in a radial direction and formed as recesses in opposite faces of the partition which communicate through a narrower radial space at one side of the bottom of each recess, the two communicating recesses being offset from each other in a circumferential direction and having the side remote from the communicating opening beveled away from such opening.

2. In a rinding mill, the combination of a rotary s ell or drum, a transverse radial partition, and means to secure said partition in place, said partition having openings extended each in a radial direction and formed as recesses in opposite faces of the partition which communicate through a narrower radial space at one side of the bottom of each recess, the two communicating recesses being offset from each other in a circumferential direction and having both sides beveled away from the communicating opening.

This specification signed this th day of August A. D. 1916.

V J OHAN S. 'FASTING.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0."

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