US1295726A - Grinding-mill. - Google Patents

Description

I. W. GARROW.

GRINDIIIG MILL. ARPLICATIQN man MAY n. self Patented Feb. 25, 12H9.

i v*Toljall whom t may concern.'

Be it known that I, JOHN WILLIS Grannow,

VAfol. thetown of Copper Cliff, in the District -of;l Sudbury, inthe Province of Ontario,

Canada, have invented certain new and use- .ful Improvements in Grinding-Mills, ot

i which the following is the specification.

M Vl invention relates t improvements in grinding. mills and the object of 'the inven- I tion is to devise a mill,` which will produce an increased grinding of the material and posltive discharge of the ground material fand: it consists essentially of a grinding i drum having tapered headshaving inclined opposing parallel inner ends havingga circular inlet and discharge orifices arranged at l ri'ghtangles tothe axis of rotation, each head taperingl from the circular end into an l ovoid opposite inner end as hereinafter more particularly explained by the/ following` y speciication.-

Figure 1. is a general perspective View of a mill.

= '.Fig. l 2, is an enlarged longitudinal section.

through the mixing drum.

Fig. '1s a sectional view of an inter changeable discharge mouth of diiierent diameter to that shown in Fig. 2.

- the central portion 2. The heads 3 i. with the anis around. which the ends 2, and 2. the hoses `formed inten al 'with such central Fig.v 4, is a View ot the discharge end l Fig. v5, is a sectionalv View on line Fig. 2. f :Fig: 6, is a longitudinal section Lnicegli tated. The `ends 2X and portion 2 arein :d such axis beingx indicated A-A 2 and heads their inner ends ccriespondo suitably se d thereto.. inthe the heads 3 and e are shown integral are 'tapered` thehead 3 being provided witn an inlet orifice 3* set at right angles to m.e

axis ofrotation A-A and the head with a discharge opening 5 around which is secured an annular ange. 7 indicates a discharge Application leii Hay l?, im?.

ingr the mill hodiv Specification o Letters Patent.

.nie-nth which is tapered in form provided at from the drum so that it can he interchanged with discharge mouths of less internal diameter such as shown in Fig. 3. By this means it will he seen that the grade formed between the lower peripheral portion of the inlet orifice 3 and the lower peripheral portion of the discharge mouth 7 may loe varied in order to suit requirements and to increase or decrease the rate of discharge. The steeper the grade between the inlet 3 and the discharge mouth 7 the greater will be the speed of the discharge through the outlet mouth and the less finely ground will he the discharged product.

it will thus he seen that a simple means is provided wherehjv the diameter of the outlet is varied for decreasing;f or increasing the grade from 'the inlet to the outlet o the mill. hs result is attained by tiltli'eeping the diameter of the outer end constant. Ey this means it will he readily understood that great inconvenience would he rendered owing to the necessitiY of rie-adjusting the line shafting. motor er other drivingineans in order that it mayv he accommodated to the new position oi the grinding mill so that it can aline up with the new axis of the mill. ln the applica tls construction the axis of the mill need not he disturbed and. thereforei the necessity For a .ting the line sliating is oloviated.

@y the above described construction of in an increased activitev and washin ac- 'niparted to the. halls indicated hy the whicln employed in this class 2uncticn of o action heine crofluced lill@ terial, I do not claim a regular and automatic sorting or separation of the coarse and tine material, further `than that as the material passes through the inill it will be acted upon in its progress through the grinding media more or less in proportion to the distance traveled. Forv this reason it may be expected that material reaching the outlet end will be more or less finely ground. As such liner material is carried to the discharge end it is gradually fed through the mouth 7, the speed at which such discharge is produced being regulated bv the internal diameter of the mouth piece 7. If it is desired to decrease the speed of the. discharge or alter the ineness of the discharged product all that it is necessary to do is to remove the mouth 7 and secure a similar mouth of smaller diameter in place. It will be un-1 derstood that while this washing action is reciprocating yet the material carried to the outlet is discharged in part and cannot re turn at the return movement. In order to lill this space a constant progression of the finely ground particles toward the outlet of the in ill is maintained. This action is much more positive than theforce acting on particles in other conical mills which consists of the resultant of the centrifugal force and or other liquid. v

In both forms shown in Figs. 1,12 and 6 and 7 an annular gear 16 is secured to the central cylindrical portion, the drum being suitably provided with annular ways 17 and 18 see Fig. 1) which are mounted on rollers 19. Although I have shown this means of mounting the drum it will, of course, be

Aunderstood that any other means may be provided.v In the -form shown in Fig. 1 the drum is rotated by means ofV a pinion 20 mounted upon a suitable shaft 21 in mesh with the annular gear 16.

In Fig. 6, I have shown an alternative kform in which the construction of inlet and outlet are modified.

In Fig. 7, I have shown a form of drum with 'the central cylindrical lportion 'dispensed with and comprising two tapered portions'Q/Q and 23 inclined at 24 forming Y their line of junction to the axis of rotation.

In grinding certain materials that are not thoroughly dried orare of a sticky or lastic nature, there is a tendency for the nel ground material to accumulate on the shel near the outlet end, where the balls or other grinding media are smaller' and-where the material is not'l so violently acted upon. In mills with regular conical ends such material accumulates in"4 a gradually increasing crust or coat-i` 'ig on the outlet cone until the balls are kept away from the shell and y cease to grind efficient-ly, finally allowing the outlet of the mill to close u entirely.

As soon as these small b'al s no longer touch the shell lates on which they are 1ntended to roll, t iey only tend to consolidate the incrustation by their tampin action on the moist or plastic fine material.

It is found that if a 'groove be cut lengthwise of the mill in the incrustation, that the balls come `again in contact with the shell plates on the outlet end and if further moist material is not added, that they tend to scour this groove wider, and the arch being weakened the incrustation breaks `and falls away from the shell. A The necessity of cutting this ve and the delay in operation due to this incrustation and its removal in mills with re lar conicalends is a source of trouble an inconvenience in the grinding of the above mentioned class of material.

This harmful result is overcome in the grinding mill, described by the peculiar construction of the ta ering ends of the mill. It will be seen from ig. 4: that a section of the tapering end, normal to 'the axis, at the junction with the rdmomble discharge nozzle, is a true circle. At the section and at any other point on the tapering en except at section w. a section normal to lthe axis of the mill is roughly egg-shaped,

with a :es of di'erent lengths at dierent points on the periphery.

As the mill revolves the pressure between the grinding plates attached to the shell and a selected ball varies with the momengrinding action at the dierent points on the periphery of a normal section in con'unction with the washing action imp. to the balls prevent the formation of an incrustetion by keeping its aibh broken'wt one or more points on the periphery of the tapering ends, avoidin the-relays and inconvenience experienced in mills with regular conical ends, when dry grinding the above materials. y.

It has been found that in order tc achieve the results claimed for the mill, such as, in-` creased agitation of the balls, forward propeiling action of the material bein ground, prevention of the formatiton of an incrustation, etc., that it is necessary to have a minimum angle of offset of about 3 degrees.

Leen

This angle orl oii'set may be described as the angle between a normal to the central axis of the mill and the line of intersection between the tapering ends of the mill at their junction, ori-if a cylindrical center tion be used, the line of junction between the cylindrical center section and the tapering end.

From this description it will be seen that I have devised a grinding mill in which-an increasedreciprocating 'or Washing action is produced so as to thoroughly grind the material Which may be fed into the mill either in a dry or wetstate, in Which simple means is provided for regulating the speed of the discharge of the material from the drum whereinv the degree of fineness to which theV material is reduced is reguN lated, such regula-tion being attained WithH out disturbing the position of Ithe drum so that the alinement of the axis of rotation and the line sha'tingv always remain constant and thereby obviates any necessity for disturbing the line shafting and driving mechanism in order to produce the above adjustment and in which the peculiar shape'- of the tapering ends of the drum prevcntthe formation of incrustations of damp and sticky material.

The advantages from having the ends of the main body portion inclined to the axis of rotation of the drum are:

1. Increased amount of grinding action,

This is due to the combined rotary and re cipiocating motion giif'ing the inaxiinun'i activity and relative motion to the :sails or other grinding media between the balle the outer shell.

v2. Accelerated discharge.

ends of the mill to the central cylindrical This is caused by the reciprocating action set up in the material that causes. any material near the discharge nozzle to be discharged in the forward surge of the n'iaterial and balls set up by the inclination of the portion.

3, The prevention .of accreticns on the Walls of the mill when grinding damp or sticky materia rii'hisjlction is obtained by the combination of the ovoidal section of the tapered ends or particularly the discarge end where the material is finer and the reciprocating inotion set up by the inclination .of these ta pered ends to the central cylindrical portion of the mill and is also due to the fact that for any given inclination of the grade of the materiel the discharge nozzle diameter will be greater than in a mill Where the axis ot the mill is tilted to this inclination to the grade line of the dal, this larger di ameter of the disc' argc nozzle helping to prevent the archin .eet necessary to foi-in accretions. 'f

TWha-1t l clainl niy inventio l'n a grinding iniii i prising a central Arif: l axis is parallel a l i of rotation

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