US1521217A

US1521217A - Grinding mill

Info

Publication number: US1521217A
Application number: US629801A
Authority: US
Inventors: Johan S Fasting
Original assignee: FLSmidth and Co AS
Current assignee: FLSmidth and Co AS
Priority date: 1923-04-04
Filing date: 1923-04-04
Publication date: 1924-12-30
Anticipated expiration: 1941-12-30

Description

. Dec.A 30, 1924.

J. s. FAS-UNG .GRINDING MILL Filed' April 4.

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JOHAN S. FASTING, 0F VALBY, NEAR OPENHAGEN, DENEJIRK, ASSG-NOR TO F. L. SIVIIDTH t CO., OF NEW YOREL Y., CRPORATGN O?? NEW' JERSEY.

GRINDING MILL.

Application filed April 4,

To all wlw/m t may concer/n.'

Be it known that I, JOHAN S. Fnsrixe, a subject of the King of Denmark, residing at Monrads Alle 9, Valby, near Copenhagen, Denmark, have invented certain new and useful Improvements in Grinding Mills, of which the following is a speciiication, rei erence being had to the accompanying drawing, forming a part hereof.

rlhis invention relates to grinding mills the type commonly known as tube mills. heretofore constructed such a grinding mill has a relatively long, cylindrical shell, sometimes of uniform diameter from end to end and sometimes with one portion of greater diameter than the other portion, and supported at its ends by trunnions which rest in suitable bearing blocks. The trunnions are hollow in order toV permit the admission at the feeding end'of the material to be ground and the discharge at the other end of the ground material. rlhe cylinder, because of the bending moment to which it is subjected by reason of its considerable length and of the weight of the Vcharge of grinding bodies and material being` ground, is sometimes supported between its ends by exterior supporting rings which rest upon suitable bearing rolls. A driving gear is also commonly applied to the cylinder by means of which the cylinder may be rotated. In order to permit the progressiveV reduction of the material being ground, it is also common to erect within .the cylinder one or more transverse partitions for the purpose of 'forming successive .grinding chambers to receive grinding bodies of different size or character,V the partitions being provided with suitable openings through which the material may pass from one chamber to the next. Among those p skilled in the art, some of the disadvantages of such grinding mills are recognized. Because of the considerable length of the cylinder and the bending moment .and other stresses to which it is subjected, the cylinder must be of great strength and therefore must be constructed of relatively heavy metal, notwithstanding the fact that the metal. is protected from wear internally by the lining of the cylinder. This is particularly true of the cylinders which have portions of different diameters. The Weight due to the strength .of metal thus required adds to the power required for the operation of the mill without proportionate results. 'The external. bearing of A S i923. sei-iai No. 629,301.

rings and their supporting rolls quickly wear out of true, causing vibration and demanding increased power for operation.. The end trunnions are necessarily of relatively small diameter and therefore limit to some extent the size of the pieces of material to be ground which can be fed into the cylinder at the feeding end. The partitions are difficult of access for renewal andrepair and in order to permit access (since the hollow trunnions are too small to permit the passage of a man) there must be provided in each chamber a manhole, which necessarily weakens the shell somewhat, requiring still greater strength of material, and brings about rapid wear internally because of the impracticability of protecting completely the manhole cover'by lining. The considerable length of the cylinder gives importance to the longi tudinal expansion and contraction of the cylinder under the constantly varying temperatures, particularly in the grinding of hot cement clinker.

It has been found, in the present invention, that the disadvantages above mentioned in the operation of grinding mills, can be overcome largely and -economy in operation effected by dispensing with the end bearing trunnions and supporting the mill by reduced bearings, of practicable diameter, between its ends. Usually, for a mill of standard length, it will be found sufficient to provide, between the extremi ties Vof the mill, two such bearings `forming middle or main grinding compartment, a primary grinding compartment overhung at one end, anda separating or screening compartment overhung at the other enc. The several compartments communicate with each other through the hollow bearing members, which need not be of large diameter, since no large pieces of material will pass through them. The feed opening at one end and the discharge opening at the other end of the mill can be made of such diameter as not only to permit the free introduction at the feeding end of lmaterial which is relatively coarse, but to permit the passage of a man so that the provision of a separate manhole in the cylindrical wall of either chamber is unnecessary. Since almost the entire end of each compartment or chamber is exposed, the bolts which hold the separating plates and liner plates at, the disclirge end of each compartment aie readily accessible, easy to inspect and easyto keep in order. The preliminary grinding chamber or compartment can be made of larger diameter than the other compartments so as properly to receive and crush the irregular and relatively large pieces of material which may be fed to it, suoli material being reduced in the preliminary grinding compartment to .a substantially uiiifo m and smaller size so that most of it will pass readily through the separator plate in the discharge end of the preliminary compartment. The bendingV moment of the middle and longer compartment of the mill is greatly reduced by the overhung preliminary grinding and separating or screening compartments kand the weight of material ein aloved for the Y L, Y Y .l

lustrated in the drawing, the mill comf prises a preliminary grinding compartment a, relatively short in'lengthand of relatively large diameter, a main grinding compartment 6,'of such length as to effect the desired reductionof the material, and a relatively short supplemental grinding comlpartment c. YThe preliminary grinding compartment a comprises end plates a and a2, the former provided with a central feed opening a3 and the latter with a central discharge vopening a4, and a cylindrical wall 0,5. Within the compartmentV and near its discharge end, is aperforated separator plate ci which hason rits discharge side a discharge cone a7 and substantially radial ribs or vanes as which lift the reduced ma-V terial which has passed through the perforations of the plate andh discharge it upon Vthecone a7 byV which it isLdirected through 1 4 ythe dischaige opening a Y .The ,main grinding compartment b also comprises end plates and b2, the former ,provided with a central feed opening b3 and the latter with a central discharge opening b4, and acylindrical shell b5. It is further provided with a separating plate which Vhas a discharge cone 57 and lifting ribs or Avanes 5,8 to edectthe discharge of the produced ymaterial which passes through the separating plate 56. The compartment 55 may also be provided externally with Va gear ring b9 by which the mill can be rotated.

The supplemental compartment V'c `.may

also comprise end plates cf and o2, Y' the former having a central feed opening 03 and the latter a central discharge opening c4; This compartment also has between the end plates a cylindrical wall of, and Vmay Vmembers al and e, which may be secured to the respective compartments by .bolts as at d and e', such bearing members being hollow so as to permit thepassage of material throughV the same, and being received in bearing blocks and f which may be mounted on suitable pedestals f2 and f3;

fr feed chute g may beiprovided forv directing into the preliminary grinding drum a the material to be ground'andfthe screening drum@ may be provided withv a discharge Vchute g. Y Y Y lt will Vbe observed that the feed'opening a3 of the preliminary grinding drum t can be made as large as maybe desired so that the feeding of the material to he ground, even in relatively large pieces, will not be interfered with. Such material as has received, in the compartment ya, the grinding necessary to permit it to pass throughthe separating plate a, will be raised by the vaiies or Yribs a? and, falling upon the cone al, willbe directed into and through the bearing member CZ, while, in like manner, the material whichhas been Y further reduced in the main vgrinding compartment b and has passed .through the separating plate-bs, will be'raised .and dis charged through-"the hollow', bearing inember e. Finally,`the material. which` may be f rther reduced in the screening drum c and passes through the separatiiigplate c, will be raisedV and discharged Vthrough the dischargeopening at. i

. It will be noted that the constructionshown permits of the securing VofV thej required strength without the employment of heavy'V iio metal, it being understood that the interior Y ,of each compartment is protected by the usual lining, not necessary tobe shown. VThe feed opening of the preliminary drum `or compartment can be made as large as desii-ed, not only to permit the feeding in of material in relatively large pieces, butvof f such size as to permit the passage of aman, thereby doing away with the necessity of providing a manhole in the side Wall of the drum, in order to give access tothe interior for purposes of replacement and repair. In like manner the openings offthe bearing members d and e and, ifnecessary, of thedisy charge end of the supplemental comparu' ment, cani-be made-of such diameteras to permit the passage of arman.

l claim as my invention:

iso p l. A grinding mill comprising a relatively long main grinding drum of relatively large diameter having end walls and a` cylindrical wall, hollow bearing members of relatively small diameter secured one to each end wall of the main grinding drum, supplemental drums of relatively large diameter each having an end wall secured to the outer end of one of the hollow bearing members, the end walls of the drum being each provided with an opening communieating with the interior of a hollow bearing member, the hollow bearing members being adapted to serve as the means for supporting the drums and to permit material treated to pass from one drum to another.

2. A grinding vmill comprising a relatively long main grinding drum of relatively large diameter having end walls and a cylindrical wall, hollow bearing members of relatively small diameter secured one to each end wall of the main grinding drum, supplemental drums of relatively large diameter and relatively short length each having an end wall secured to the outer end Vof one of the hollow-bearing members, a bearing block for each of the hollow bearing members, the end walls oi the drums being each provided with an opening communicating with the interior of a hollow bearing mem- Yber, the hollow bearing members being adapted to serve as the means for supporting the drums and to permit material treated to pass from one drum to another.

3. A grinding mill comprising a relatively long main grinding drum of relatively large diameter having end walls and a cylindrical wall, hollow bearing members of relatively small diameter secured one to each end wall of the main grinding drum, supplemental drums of relatively large diameter and substantially equal relatively short length each having an end wall secured to the outer end of one of the hollow bearing members, a bearing block for each of the hollow bearing members, the end walls or' the drums being each provided with an opening communicating with the interior of a hollow bearing member, the hollow bearing members being adapted to serve as the means for supporting the drums and to permit material treated to pass from one drum to another.

4. A grinding mill comprising a preliminary drum having end walls and a cylindrical wall, a main grinding drum having also end walls and a cylindrical wall, a supplemental grinding drum having end walls and a cylindrical wall, hollow bearing members having their opposite ends secured respectively to the adjacent end walls of the preliminary drum and the main drum and the adjacent walls of the main drum and the supplemental drum, and bearing blocks for said bearing members, the preliminary drum having near its discharge end a separator plate with lifting ribs and a central discharge cone.

5. A grinding mill comprising a preliminary drum having end walls and a cylindrical wall, a main grinding drum having also end walls and a cylindrical wall, a supplemental grinding drum having end walls and a cylindrical wall, hollow bearing members having their opposite ends secured respectively to the adjacent end walls of the preliminary drum and the main drum and the adjacent walls of the main drum and the supplemental drum, and bearing blocks for said bearing members, the main drum having near its discharge end a separating plate with lifting ribs and a discharge cone.

This specilication signed this 15th day of March A. D. 1923.

JOHAN S. FASTING.