US2574979A - Vertical axis dispersion mill with drive motor supported from conical grinding head - Google Patents

Description

Nov. 13, 1951 w. Mr-:sslNGER 2,574,979

VERTICAL AXIS DISPERSION MILL WITH DRIVE MOTOR SUPPORTED FROM CONICAL' GRINDING HEAD .any

Nov. 13, 1951 w. MEsslNGER 2,574,979

VERTICAL AXIS DISPERSION MILL WIT RIVE MOTOR SUP EAD PORTED FROM CONICAL GRIND H Y INVENTOR.

W/z//W Miss/5M Patented Nov. 13, 1951 VERTICAL AXIS DISPERSION MILL WITH DRIVE MOTOR SUPPOBTED FROM CONI- CAL GRINDING HEAD William Messinger, Philadelphia, Pa. Application March 14, 1949, Serial No. 81,341

Claims. (Cl. 24J- 111) The present invention relates to machines for preparing dispersions of a continuous fluid phase from dispersions of a discontinuous phase, either solid or liquid. More particularly. the invention embodies a mechanism for intimately dispersing solid particles, such as paint pigments, in liquid vehicles such as varnishes, oils and resins.

Yet another object of the invention is to provide a mechanism of the above character by means of which dispersions oi the type above referred to may be homogenized, stabilized or refined.

There are various types of mills now in current use for preparing dispersions of the above character. These mills include ball mills, pebble mills and the like, and it is generally recognized that such mills are ineicient, not only in that they require excessive power, but also in the length of time required to bring about a desired degree of dispersion. It is also generally known that, in addition to the objectionable noise generated by these mills and to their relatively large size, much of the power required for their operation results in heating the dispersion rather than sub-dividing the pigments being milled.

In mills of the type using conventional rollers to accomplish the dispersion, the above described disadvantages of ball and pebble mills reappear, and in their operation many pigments must be passed through these ,roller mills repeatedly in order to be adequately dispersed in the vehicle. In the operation of colloid mills the output is low, or else the resulting dispersion is relatively coarse.

. In order to overcome the foregoing disadvantages, the present invention provides a mill by means of which particle-size reduction and dispersion of substances lare accomplished effectively, rapidly and efficiently. A mill constructed in accordance with the present invention'is structurally compact and is characterized by relatively low power consumption, while at the same time, forming a desired dispersion in a single pass of the materials through the mill.

A further object of the present invention is to provide a mill of the above character, the' milling components of which are so formed that particle-size reduction is accomplished surely and eile'ctively regardless of the physical character of the product being ground or dispersed and regardless of the properties of the vehicle in which the particles are being dispersed, if the mill is used for preparing dispersions.

Other advantages of the invention will appear as it is described in gre/sier detail in connection with the accompanying drawings. wherein:

Figure 1 is a view in vertical section, taken on a plane passing through the axis of a mill constructed in accordance with the present invention and showing the component parts of such mill;

Figure 2 is a partial view similar to Figure l, but taken on the plane indicated by the arrows 2-2 of Figure 3:

Figure 3 is a view in horizontal section, taken on the line 3-3 of Figure 2 and looking inthe direction of the arrows; and

Figure 4 is a partial view in horizontal section taken through the set screw 41 and showing a portion of the motor housing and frame.

Referring to the above drawings, the frame of a grinding or dispersing mill constructed in accordance with the present invention is illustrated at I0. This frame is .formed to stand upon a supporting surface in an upright position. as illustrated in Figure 1. It is formed with an annular horizontal bearing surface II to which is secured the flange I2 of a cylindrical supporting sleeve I3 carried within the frame at the upper extremity thereof. Bolts I4 serve to secure the flange l2 to the frame I I. The sleeve I3 is formed with an inwardly extending flange I5 which supports a shell I6 which serves as an outer grinding surface lin a manner to be described presently. 'I'he outer shell I6 may be secured in position by means of a top member I1 having a bowl or hopper I8 formed therein and into which the material (and vehicle, if the mill is operating as a dispersing mechanism) is fed. The top I1 is formed with a shield I9 to prevent the deposit and caking of material on the elements beneath the shield, the top I1 being threaded at 20 to the sleeve I3 so that it is seated against the shell I6.

At the lower extremity of the sleeve I3 a depending skirt 2| is formed, this skirt having secured thereto, by means of bolts 22, a ring 23. This ring is formed with inwardly extending arms 24 having, at their inner ends, a central collar 25, passages 24' thus being formed through which the ground material passes. Discharge tubes 26 are secured to the ring 23 and collar v25 to receive skirt 2| form a discharge chamber 30 for receiving material that has passed through the grinding components to be described.

The grinding components of the mill include.

in addition to the inner cylindrical surface of the shell i8, a plurality of conical rollers Il and a grinding head I2 having a conical surface and formed upon an arbor Il. The conical rollers 2l are secured in a cage by stay braces Il which are secured to top and bottom end plates ll and 30, respectively. The end plates and stay braces thus form a cage upon which the conical rollers il are mounted. The bottom plate It is formed with a downwardly extending skirt 31 within which a thrust bearing 38 is secured. The inner race of the thrust bearing is supported upon the spider 2l. and thus it will be seen that the vertical resultant of the forces which pinch the conical rollers between the grinding head and shell Ii is carried by the spider 28, and thus upon the stationary sleeve I3.

Beneath the spider 2l there is secured to the arbor 3l a collar ll having a iiange 40 which projects outwardly and above the collar 25 to serve as a inger to prevent the material or dispersion from flowing downwardly between the collars 25 and 39.

At the lower end of the arbor 33 there is provided a coupling Il to which the drive shaft 42 of the rotor Il of a suitable electric motor is secured. The stator 44 and housing l5 of the motor are received within and located by suitably formed surfaces 46 within the frame I0. Set screws 41 engage and anchor the housing 45 against rotation but permit vertical movement thereof.

The upper extremity of the grinding head 32 is formed with a chamber I8 into which material may flow from the hopper or cavity I8. Radial openings Il at the bottom of the chamber 4B cause material therein to be thrown outwardly during operation, and the material being ground or dispersed is thus spattered over the rollers and distributed over the conical surface of the grinding head and other related grinding surfaces.

It will be seen that the direction of taper of `the rollers 3i is reversed with respect to the direction of taper of the grinding head 32. The included angle of taper of the rollers is onehalf that of the grinding head, enabling the assembly to fit into the cylindrical bore of the shell I8. The rollers thus have full elemental line contact with the tapered grinding head and with the cylindrical bore of the shell. In this fashion the effect of the weight of the motor, arbor and grinding head is to produce an enlarged resultant force which is impressed normal to the conical Vsurface of the rollers and their engagement with the grinding head and the inner surface of the shell i6.

In operation, the arbor is rotated at a relatively high speed, and there results an operation under which each particle passing through the machine is subjected to a great number of impacts and an enormous crushing force before it can descend vertically and reach the discharge cavity 30. It will be observed that since the conical rollers have their tapers inclined oppositely to that of the grinding head, there cannot be pure rolling motion between these elements. The largest diameter of the grinding head drives the smallest diameter of the rollers and conversely.

` the smallest diameter of the grinding head drives the largest diameter of the rollers. Inasmuch as the rollers are rigid and the inclination of their axes is fixed by the roller cage. there can only be one transverse plane upon which pure rolling motion can take place. It may be assumed that this plane is intermediate the length of the conical surfaces. Thus, in all other positions along the rollers, the percentage of sliding with respect to rolling motion increases as the respective positions advance toward either end of the rollers. As a result, there is not only rolling contact, but there is. in eect. a smearing, sliding, scrubbing and shearing action upon the material passing through the grinding components. and it is this action that forms the intimate dispersion and the effective particle-size reduction previously referred to.

From the foregoing it will be seen that the parts of the mill are few in number and simple in construction. so that they may be readily assembledA and dismantled for the purpose of cleaning, maintaining and repairing. Because of this. it is a relatively simple matter to use the mill for different products without causing contamination of later processed products.

' While the invention has been described with specific reference to the accompanying drawings, it is not to be limited save as defined in the appended claims.

I claim:

l. Apparatus for reducing the particle size of materials comprising a supporting frame, a stator mounted in the frame and having a substantially vertical inner cylindrical grinding surface, a plurality of conical rollers in the stator with their smaller ends uppermost, means to support the rollers in grinding relation to the cylindrical surface, a central rotatable conical grinding member engaging the rollers and having its smaller end lowermost, a shaft extending downwardly from the control member, a motor having a casing, a rotor in the easing fixed to the shaft, the motor being supported by the shaft and urging the central me ber downwardly to force the rollers out towar the cylindrical surface, and means in the frame restraining the motor casing against rotation.

2. Apparatus, according to claim 1, wherein the included angle of taper of the rollers is onehalf the included angle of taper of the central member, and the direction of taper of the central member is opposite to that of the rollers.

3. Apparatus for reducing the particle size of material comprising a cylindrical shell, means supporting the shell with its axis vertical, a plurality of conical rollers, a cage supportin the rollers with their smaller ends uppermo for relative rotation about their axes and for bodily movement around the axis of the shell. the

f rollers being movable radially in the cage into engagement with the interior surface of the shell, means supporting the rollers against downward movement out of the shell, a central rotatable conical member engaging the rollers and exerting downward force on the member to urge the rollers outwardly, the central member having its smaller end extending downwardly, the tapers of the rollers and the conical member being complemental and their diameters being suillciently great to restrain the conical member against downward movement ot the shell, an arbor depending from the central member. and a motor carried by the arbor.

4. Apparatus, according to claim 3, wherein the central member is formed with an axial chamber and at least one radial duct extending to the outer surface of the member to receive material to be reduced and deliver it to the surfaces of the rollers.

5. An apparatus for reducing the particle size of materials, comprising a frame. a hollow annular shell having an-inner continuous grinding surface mounted near the top of the frame with its axis substantially vertical, a frusta-conical central member substantially concentric with the inner surface of the shell. the central member having its larger diameter end uppermost, a plurality of frusto-conical rollers interposed between the shell and the central member, means supporting the rollers against downward movement out of the shell, the tapers of the rollers and their inclination relative to the axis of the shell disposing their inner surfaces complementally to the central member to support it against movement out of the shell in a downward direction, and the weight of the central member urging the rollers outwardly against the shell, an electric motor having a rotatable drive shaft mounted in the frame below the shell and freely movable up and down in the frame, means retaining the motor against bodily rotation in the frame, and means connect- 'ing the drive shaft to the frusto-conical mem- REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 232,419 Smith Sept. 21, 1880 739,492 Groves Sept. 22, 1903 1,444,485 Thomas Feb. 6, 1923 1,750,088 Bragard Mar. 1l, 1930 1,774,464 Wood Aug. 26, 1930 1,960,708 Loomis May 29, 1934 2,204,140 Langbein June 11, 1940 2,428,415 Eppenbach et al Oct. 7, 1947 2,464,733 Traylor Mar. 15, 1949 FOREIGN PATENTS Number Country Date 205,481 Germany Jan. 6, 1909

Images