US2309078A - Grinding mill - Google Patents

Description

Jan. 19, 1943.

P. HOLLSTEIN ET4AL GRINDING MILL Filed Jan. 23, 1939 4 Sheets-Sheet 1 N v E N T o R 5 Paul Ho/lsfellz George Jae/r ,Umvw a ATTORNEYS.

Jan. 19, 1943. P, HOLLSLI'EIN EI'AL GRINDING MILL Filed Jan. 25, 1959 4 Sheets-Sheet 2 I N V EN TORS Pay/Ho/Bfem ATTORNEYS.

Jan. 19, 1943. T P. HOLLSTEIN ETAL 2,309,078

GRINDING MILL Filed Jan. 25,1939 4 Sheets-Sheet 5 ml I INVENTORS Paul Hal/sfem By George Jack Gym vmw W v ATTORNEYS.

Jan. 19, 1943. .P, HOLLSTEIN ETAL 2,309,078

I GRINDING MILL Filed Jan. 23, 1939 4 Sheets-Sheet 4 Patented Jan. 19, 1943 orsics GRINDING MILL Paul Hollstein,

Carlstadt, and George Jack,

Rochelle Park, N. J., assignors to J. M. Lehmann 00., Inc, New York, N. Y., a corporation of New York 6 Claims.

Thi invention relates to grinding mills, especially mills of the disk type which are suited for grinding materials in the wet or fiowable state, such as cocoa liquor, inks, paints, pigments and the like, and has for an object the provision of improvements in this art.

One of the objects of the invention is to provide a horizontal disk mill, that is, a mill having disks disposed in horizontal planes and rotating about a vertical axis, of an improved design wherein a plurality of pairs of Working faces form a plurality of material receiving spaces, and wherein material is fed in parallel and accurately measured amounts to the spaces. Another object is to feed material in accurate amounts under pressure. Another object is to pre-cool the material before it reaches'the mill to keep the temperature low in grinding and avoid injury to the product,' such as burning if excessively'high temperatures are developed in grinding due to frictional heat. There is no necessity for cooling after the grinding operation.

Other objects and various features of novelty of the invention will be apparent from the following description of an illustrative embodiment thereof shown in the accompanying drawings, wherein:

Fig. l is a side elevation of a plant embodying the multi-disk grinding mill;

Fig. 2 is a side elevation looking at the right side of Fig. 1;

Fig. 3 is a vertical section through the grinding mill;

Fig. 4 is a top plan View;

Fig. 5 is an enlarged partial vertical sectional view;

Fig. 6 is a horizontal section taken on the line E6 of Fig. 5; and

Fig. 7 is a horizontal section taken on the line 3-7 of Fig. 5.

As shown in Figs. 1 and 2, the plant comprises a disk grinding machine H1, a mixer and pre-cooler l I, and a pre-grinder of some suitable type (not shown) for supplying relatively coarse ground material in liquid form to the mixer ll.

The pre-grinder is disclosed and claimed in a co-pending application, Serial No. 257,086 filed February 18, 1939. The material supplied may be cocoa liquor and may enter the tank of the mixer l l by Way of two feed pipes l2.

The mixer is provided with a jacket 83 for Water which enters by way of supply pipe is and leaves by way of outlet pipe it. This pre-cooling dissipates the heat of the previous grinding and anticipates the heating of the succeeding grinding operation by the disk mill. Overheating is, thus avoided.

The mixing blades in the mixer I l are mounted on a shaft it which is driven by a motor Ml through pulleys and belts H. Conveniently, the mixer is mounted on a ceiling support l8 above the grinding mill In in order that the liquor may flow downward by gravity, as by a supply pipe l9.

The disk mill l0 comprises a frame 29 supported upon a base "2!, a plurality of grinding disks 22, 23, 24, and a discharge basin 25. In the present embodiment the lower disk 22 and the upper disk 2d are fixed, except for vertical adjustment, and the center disk 23 rotates. The disks may be faced with a homogeneous stone, such as Alundum or Aloxite or a natural stone of high abrasive character and form between their faces the grinding spaces 23 and 21.

The lower and upper disks or stones 22 and 24 are mounted in shrouds 29 and 3t! respectively which are supported upon a plurality of bolt and spring devices 3! anchored in the frame 20. As best shown in Fig. 5, the bolts 31a with the springs 33) are supported in gears 32, all of each set of which (3 shown) mesh with central ring gears 33 mounted upon the hubs 34 formed with the shrouds 29, 39. The ring gears 33 are rotated and adjust all of the bolt and spring supporting devices 3| in unison for each stone by gears 33 secured upon shafts 36 rotatably mounted in bearings 3? secured to the frame 20. On their outer ends the shafts 36 are provided with bevel gears 38"meshing with mating bevel gears 39 secured upon adjusting shaft 1:6. The shafts 43 are mounted in fixed bearings 6!, Q2 and are rotated for adjusting movement by the handles 43. Pointers Mia threaded on the shafts cooper'ate with fixed scales Mb to show the positions of the stones.

The gears 32' are rotatable'on the bolts 3la and are provided with threaded hubs 32a which cooperate with threaded sleeves 32b carried in the frame 29.

The center stone 23 is fixed in a vertical position but rotates and may be adjustedto some extent horizontally. It is mounted in a shroud 28 carrying a bull ring gear M and a fiat runner track 5.

The gear M. meshes with a pinion 43 fast on a drive shaft 41 mounted in fixed bearings 48. The shaft 151 is driven by a motor M2 through pulleys and belts it. The shaft 41 carries a positioning roller 56 engaging a rim guide surface 5| 55 formed on the shroud 28 adjacent the runner track 45. At other points around the circumference of the guide surface 5| there are other guide rollers 52 eccentrically mounted on adjustment shafts 53 (Fig. 5). This provides that the ring gear 44 will always be kept in mesh with the pinion 45 and that the circular shroud surface 5| will be closely retained between the guide rollers 5|], 52, 52. The flat track 45 rides upon a plurality of supporting rollers 54 rotatably mounted on shafts 55 held in fixed supports 56.

No claim is made herein to the rotatable center disk, supported and driven at its outer periphery, and the non-rotatable upper and lower disks with adjustable spring backing supports therefor, except in combination with the additional elements herein described and specifically set forth in the appended claims.

As shown in Figs. 5, 6 and '7, the means for adjusting the rollers 52 comprises an eccentric sleeve 59 rotatably mounted on the fixed shaft 53. The sleeve 59 has rigidly secured thereto, as by threaded key pins 69, a flange headed member 6|. The sleeve 59 is held in rotated positions by a clamping screw 62 threaded in the flange of member 6| and passing through an arcuate slot 63 of a collar 64 rigidly secured to the shaft 53 by a pin 65. When the set screw 62 is loosened the eccentric sleeve 59 may be rotated to move the ball bearing assembly and the roller 52.

When the set screw 62 is tightened the parts may be locked in adjusted position.

As shown in Fig. 3, material to be ground is separately supplied to the spaces 26 and 21 between the grinding disks by pipes 70 and H, respectively, which have a tight joint and permit the required movement between parts. As seen in Figs. 1 and 2, the pipes 10 and H are separately fed with fluid in accurately measured amount by pumps 12 and 13 respectively. The pump 12 receives fluid from the feed pipe I9 by way of the pipe 74 and delivers to the lower pipe 10 by way of a pipe '15. The pump 13 receives fluid from the feed pipe l9 by way of the pipe 76 and delivers to the upper pipe H by way of a pipe H. An overflow pipe 18, which may be provided with a pressure valve if desired, leads from the pipes 'H and 1'! supplying fluid to the upper space 21 back tothe mixer Similarly an overflow pipe 19 leads from the pipes 10 and I5 supplying fluid to the lower space 26 back to the mixer.

Both of the pumps 72 and 13 are preferably of the positive feed type, such as lobed or gear pumps, which continuously deliver accurately measured amounts of fluid under pressure to the grinding spaces of the discs. The supply to both spaces may be effectively regulated to obtain the desired flow of the product being processed between the grinding surfaces, this flow being further regulated by varying the spacing of the disks through suitable adjustments. By these provisions it is possible to increase the output of the mill and obtain a more uniform product The mountings for the center and lower disks are provided with ample openings around their edges for the flow therethrough of ground material from above.

The operation of the mill will be clearly understood from the foregoing description. It will also be clear that the mill may readily and easily be adjusted because of the nature and accessibility of the parts; that the drive is very easy; that assembly and disassembly may be readily accomplished; that the material will flow freely but will not be overheated; that the grinding will be rapid and uniform; and that in general '3 by the rotating stones.

the invention provides distinct improvements in this art.

In the present tri-stone mill it is possible to balance the center grinding member by maintaining a small pressure differential between feed pressure in the lower grinding space and the pressure maintained in the feed to the upper grinding space. It will be noted, for example, that the face area of the center stone may be approximately 2000 square inches and its total weight approximately 2000 lbs., so that a feed pressure differential of only 1 lb. per square inch will serve this purpose.

The principal limitation as to output and fineness of grinding, in mills of the old construction, was the necessity of avoiding excessive heat due to the grinding friction. This necessity of avoiding temperatures at which the product would burn controlled the speed at which the millstones could be rotated over each other; furthermore, to maintain a steady flow of the product through the mill under the normal static head of the material in the feed hopper and centrifugal action developed through rotation, the millstones were dressed with deep radial furrows and finer grooves carried through to the periphery. With this system the rate of output was definitely restricted and the fineness could not be controlled very well because of the possibility of sufficiently ground product carrying some of the coarser insufficiently ground material out through the finer grooves obtaining with the old style stone dressing.

In the design of the present mill it is proposed to offset part of the heat of grinding through the pre-cooling. The tendency to carry coarse insufliciently ground material out with ground liquor is avoided in the new construction by maintaining a marginal area of approximately 1" width upward on the millstone periphery where no furrows or other dressing obtains. In this area the millstones operate to a ground fit. Under the old system this would have effectively shut off the principal output. With the employment of pressure feeding as in the new construction the product to be ground is actually forced through the mill and passes between the ground surface of the two millstones at the peripheral grinding area as a thin film traveling at considerable speed-of necessity being reduced to the fineness required due to millstone adjustment and because of the high speed of movement through the milling surfaces acting as a selfcooling agent.

Pressure feeding combined with pre-cooling makes it possible to speed up the millstones considerably beyond what was previously possible, without generating injurious temperature within the mill. Furthermore, the rate of grinding and productivity of the mill can be boosted far beyond what was possible in production with the former gravity feed mill in which the film of product being ground traveled through the mill principally through centrifugal forces developed In the new construction the centrifugal forces which tend to transfer the product particle from the center to the periphery of the millstone are combined with a radially active feed pressure tending to speed the particle rapidly through the mill in which, however,

due to the marginal grinding surface at the periphery, it must be converted to the desired fineness. The mill has a resulting production far beyond that of any previous construction and combines this high production, nevertheless, with a uniformness of fineness in grind never before obtainable. And the rate of production is directly controllable through changing the feed pressure.

While one embodiment of the invention has been described in detail in order to illustrate the principles of the invention, it will be understood that the invention may be variously embodied within the limits of the prior art and the scope of the subjoined claims.

We claim:

1. A grinding mill suitable for grinding cocoa liquor and similar substances, comprising in combination, a top horizontal disk and a bottom horizontal disk adjustable vertically, and a center horizontal disk mounted in a fixed vertical position as to lower limit but adjustable horizontally, the horizontal adjustment of the center disk being affected by a plurality of eccentrically adjusted guide rollers.

2. A grinding mill suitable for grinding cocoa liquor and similar substances, comprising in combination, a rotating grinding disk, rollers supporting the disk for lateral adjustment, a circular guide band and ring gear on the disk, a fixed shaft carrying a roller and a gear adapted to cooperate with said band and ring gear respectively, and a plurality of adjustable rollers spaced around the circumference of said band, a fixed shaft or post for each adjustable roller, a flanged eccentric sleeve rotatably mounted on said post and within a roller, a collar fixed to said post adjacent said sleeve flange, said collar having an arcuate slot, and a set screw in said slot threaded into said sleeve flange for holding the sleeve in adjusted positions on the post.

3. A grinding mill suitable for grinding cocoa liquor and similar substances comprising in combination, spaced upper and lower horizontal grinding disks which are resiliently mounted and separately adjustable for axial movement, an imperforate center grinding disk rotatably mounted on a track and rollers in a fixed lower position and free to move toward an upper position limited by the upper disk, lateral guiding rolls for said center disk and adjusting means therefor, means for driving the center disk at its periphery, said center disk having upper and lower grinding surfaces with narrow fiat band faces near the periphery cooperating with similar grinding surfaces of the upper and lower disks to define two grinding spaces, and means for feeding material in predetermined amounts under pressure to each of the grinding spaces.

4. A grinding mill suitable for grinding cocoa liquor and similar substances comprising in combination, spaced outer grinding disks which are resiliently mounted and separably adjustable for axial movement, an imperforate center grinding disk defining with the outer disks two separated grinding spaces which are unobstructed except by the grinding elements of the disks, said center disk being rotatably mounted at its periphery in a fixed position in one axial direction and free to move in the other axial direction limited by the adjacent outer disk, lateral guiding means for said center disk at its periphery, means for driving the center disk at its periphery, and means for feeding material in predetermined amounts under pressure to each of the two grinding spaces formed between the center and outer disks.

5. A grinding mill suitable for grinding cocoa liquor and similar substances comprising in combination, a pair of spaced non-rotatable outer grinding disks which are normally fixed in an axial direction, an imperforate center rotating disk defining with the two outer disks two separate and distinct grinding spaces, said disks being provided with grinding surfaces having narrow flat band faces near the periphery of the disks, said center disk being mounted on a fiat track and supporting rollers beyond its periphery to limit movement in one direction and to permit lateral adjustment without afiecting its axial position, means to adjust the lateral position of the center disk upon its support, and means for supplying fiuent material under independent pressures to each of the two grinding surfaces.

6. A horizontal disk grinding mill of the character described comprising, in combination, spaced and non-rotatably mounted upper and lower grinding disks, a center disk located between the upper and lower disks and defining with them two separate grinding spaces, means for the individual adjustment of the upper and lower disks toward and from the center disk, means for delivering material under predetermined pressure independently to each of the separate spaces for grinding and to force the ejection of ground material from said spaces said disks being formed with opposed grinding surfaces restricting the outflow of material therefrom, means for controlling the fiow of material to the individual spaces, means for rotatably supporting the center disk from its periphery and for determining its minimum clearance relative to the lower disk, a peripheral driving means for the center disk and individual, adjustable pressure means for the upper and lower disks operable to yieldingly resist their movements away from the center disk and to maintain predetermined grinding pressures.

PAUL. HOLLSTEIN. GEORGE JACK.

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