US2626757A - Attrition mill - Google Patents

Description

E. C. SHAW ATTRITION MILL Filed Jan. 22. 1949 Jan. 27, 1953 Patented jan. 2.7-, l1953 UNITED .STATES PATENT OFFICE ATTRITION MILL Ernest C. Shaw, Milwaukee, Wis., assigner to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application January 22, 1949, Serial No. 72,158

8 Claims.

This invention relates to attrition mills, and more specifically to attrition mills embodying a spout and, if desired, liquid jets for moistening the material being ground. The principal object of the invention is the provision of new and improved mills of these types. A more specic object of the invention is to control the admission of air to the mill and the discharge of the ground stock. A still further object of the invention is the provision of means for allowing eflcient reversible action of the unit.

Other objects will appear hereinafter as the description of the invention proceeds.

The novel features of the invention and how the objects are attained will appear from this specification and the accompanying drawings forming a part of this application, and all these novel features are intended to be pointed out in the claims.

In the drawings:

Fig. 1 is a central vertical section of an attrition mill embodying the invention taken along line I-I of Fig. 2; and

Fig. 2 is a plan View partly in horizontal section.

In the embodiment illustrated the attrition mill is shown as comprising a structure including a main frame 3 and a top frame 20.

The main frame 3 generally is a cylindrical wall 4 formed with a pair of end plates designated as a base plate 5 and a cover plate 8 suitably secured thereto by means such as welding or in any other suitable way. The base plate 5 is a square member having a central opening 6, and provided with bolt holes 1 for anchoring the entire attrition mill unit to any suitable foundation. The cover plate 8 has an annular recess 9 concentric with a central bore Ill therethrough, for receiving a. top plate I'I provided with sealer rings I2 for preventing the leakage of lubricant to the top frame 20. A hollow cylindrical member I3, axially positioned within the main frame 3, is secured therein to the cover plate 8 and an intermediate flange I4, for radially and longitudinally supporting a main shaft 41. An annular external ange l5 secured to a ridge I6 of the main frame 3, is formed with bolt holes I1 to receive bolts I8 extending through a split iiange I9 of the top frame ZIJ for rigidly securing the frames to one another.

The top frame 20 comprises essentially an arcuate wall portion 2l merging with spaced opposite tangential portions 22 and 23. Functionally integral with the top frame 20 is a lower member 24 and an upper member 25 comprising substantially an inwardly extended flange 25 and an upper enclosure 21. The tangential portions 22 and 23 converge from their point of tangency and form with the lower member 24 and the upper enclosure 21, a spout 28 herein shown as rectangular in cross section, provided at its end with an outward extended flange 29.

The inwardly extended flange 26 is adapted to receive cooperatively therethrough a tapered surface SI of a ring 3i), which is adjustably mounted thereon by means of bolts 33. The ring 3l) is constructed with circumferential threads 32 for engaging complementary threads 35 on the outer periphery of a top adjusting head 34. Separated from the complementary threads 35 by a groove 36, are machined gear teeth 31 to function in meshing relationship with a pinion 4U, manually rotated by a handwheel 4I. Adjacent the handwheel 4I is a pointer 42 to cooperate with markings 43 on a calibration plate 44. A locking device 45 fixed to the inwardly extended flange 26 for radial withdrawal and interengagement with the gear teeth 31, is provided for positively holding the top adjusting head 34 to its adjusted position. An upward cylindrical extension 38 of the top adjusting head 34 forms a feed opening 80 through which the material to be ground is fed to the unit.

Protruding into a grinding chamber 4G, provided by wall means dened essentially by the top frame 2i), is one end of the main shaft 41, to which is secured as here shown by means of a key 48, a runner head 49. Disposed in the chamber 46 are a plurality of grinding plates. In this instance an upper faced grinding plate 50 is rigidly fixed to an accurately finished upper surface of the runner head 49, in cooperative grinding relation with a lower faced grinding plate 5I, which is stationarily secured to a mounting portion 39 of the top adjusting head 34. Each of the grinding plates 50 and 5I is formed with sharp corrugations 52 arranged in a fashion most desirable for the type of materal to be ground. A breaker head 53 is fixed to the end of the main shaft 41 by a bolt-nut 54 and fitted onto the runner head 49 to facilitate the entry of stock between the grinding plates 50 and 5I. To the lower surface of the runner head 49, there are mounted preferably at least two fan blades 55 diametrically opposite each other, and radially extending to the outer circumference of the runner head. The fan blades 55 are preferably provided to better circulate or Whirl the air in the chamber 46.

The main shaft 41 extends from the grinding chamber 46 axially through the hollow cylindrical member I3, and terminates within the space between the base plate and the intermediate fiange I4. A bushing 56 is secured to the cylindri-cal member I3 by means of a holding ring 51, receiving bolts 58 for engagement with threads formed in the bushing. An antifriction bearing 59 is located near the upper end of the bushing 56, for the radial rotational support of the main shaft 41, and a pair of similar antifrictional bearings 6I) is located at the opposite end for the dual purpose of radial rotational support and for absorbing the downward thrust of the main shaft created during the grinding operation.

A reversible spout 6I, det-achably receivable within the rectangular spout 28, is adapted for cooperative relationship with the grinding plates 50 and 5I, and positioned in accordance with the direction of rotation of the runner head 49, as illustrated in the drawings by the arrow 49a. The detachable spout 6I is preferably provided with side extensions, substantially extending the tangential portions 22 and 23. The side extensions comprise a wall 63 perforated as here shown, and a continuous wall 64, the end vertical edges of which are rigidly secured to a complementary flange 65 and an outer flange 66. The complementary fiange 65 is secured to the outward extended iiange 29 by means of bolts 61, whereas the outer ange 66 is secured to a conduit (not shown) if necessary, for the further conveyance of the ground stock for subsequent treatment. Lower and upper plates 68 and 6.9, respectively, are secured to and bounded by the horizontal edges of the side extensions and spaced parallel a distance slightly less than the vertical distance between the lower member 24 and the upper enclosure 21. Internally fixed to the lower and upper plates 68 and 69, respectively, are guiding partitions 10 comprising an arcuate vertical partition 1I, an admission partition 12 and a main partition 13, principally termed a discharge partition. The arcuate partition 1I diverges somewhat, in the direction of rotation, with respect to the periphery of the grinding plates 53 and 5I, from a portion 14, of the main partition 13. The degree of divergence may vary and is more or less determined by the curvature of the arcuate partition 1I which in turn is designed for most eiiciently guiding ground stock in ther grinding chamber 46. The portion 14 is constructed to extend in proximity to the outer circumference of the grinding plates 56 and 5|. The admission partition 12 is located essentially parallel to the perforated Wall 63 and the tangential portion 22 of the top frame 20, and spaced therefrom a distance so that its innermost vertical edge joins the diverged edge of the arcuate partition 1|. The opposite vertical edge of the admission partition 12 is secured to the main partition 13, and forms therewith and the arcuate partition 1I a dead air chamber 15. The main partition 13 extends from its portion 14, essentially parallel to the continuous wall 64, and spaced therefrom, as here shown, a distance approximately twice the distance that the admission partition 12 is spaced from the tangential portion 22 of the top frame 20.

Reversible water jets 1G uniformly disposed in tangential relationship with the arcuate wall portion 2 I, are positioned as herein shown in cooperation with the direction of rotation of the runner head 49. A fixed water jet 11 may also be secured to the wall G3, or to another suitable means if the perforated wall 63 is not provided, in parallel association with the tangential portion 22.

Preparatory to operation, the size of the ground stock is predetermined by the setting of the top adjusting head 34 to the desired marking 43 on the calibration plate 44 to correspond with the pointer 42, by means of the handwheel 4i. The reversible spout 6I and the reversible water jets 16 are positioned in accordance with the rotational direction of the runner head 49.

In operation then, material to be ground is introduced to the attrition mill through the feed opening 80, and urged between the grinding plates 56 and 5I by the action of the breaker head 53. As the material passes through the corrugations 52 it is ground into particles and tangentially expelled into the grinding chamber 46 surrounding the grinding plates 56 and 5I. The admission partition 12 forms with the tangential portion 22 of top frame 26, an admission passage 18 through which air is aspirated tangentially into the grinding chamber 45. This aspirating effect is accentuated due to the rotational effect of the fan blades 55. The perforated wall 63 may be provided if there is danger of foreign matter entering the admission passage 18 along with the air. The turbulence created within the grinding chamber 4B by the circulating air, tends to suspend the particles for rapid tangential discharge along with the air through a discharge passage 19 formed by the discharge partition 13 with the tangential portion 23 and the continuous wall 64. The portion 14 diverts the particles that are expelled from between the plates 56 and 5I near the discharge passage 19, which possess an inertia force greater than can be overcome by the blast of air, into the discharge passage. The particles expelled immediately beyond the DO ltion I4 are guided by the arcuate partition 1I substantially tangential into the incoming stream of air.

Due to the adhesive properties that certain material which is ground may have, the particles might adhere to each other and form sizable masses or may cling to the top frame 2 6 and choke the machine. Therefore water may be injected into the grinding chamber 46, through the reversible water jets 16 and the fixed Water jet 11', to agitate the groundl stock and hydraulically aid in the discharge thereof.

It is obvious that the unit will function in the same manner upon the reverse rotation of the runner head 49. That is to say, if it is desired to operate the attrition mill in the opposite direction to more equally distribute the wearing effects upon the corrugations 52, or for any other reason, the reversible spout 6I may be detached from the outward extended flange 2 9, rotated 180 degrees and resecured. It is readily seen that the reversible liquid jets 16 can also be turned 180 degrees to cooperatively function with the direction of discharge of the ground stock. The xed water jet 11, if used, would necessarily have to 5. be provided with a ilexible or disconnectable connection (not shown), in order to permit reversal of the spout 6I.

It will be evident that for either direction of rotation oi the mill and with the reversible spout 6l in the correct relation to the rectangular spout 28 for a given direction of rotation, a separate passage 'i3 is provided for admission of air to the grinding chamber 46 in the general direcftion in which the air tends to flow in the chamber at the place of admission due to the rotation of the runner head 49, and a separate passage 79 for discharge of ground material from the grinding chamber in the general direction in which the material tends to flow in the chamber at the place of discharge due to the rotation of the runner head.

It is claimed and desired to secure by Letters Patent:

1. In an attrition mill comprising in combination, wall means forming a grinding chamber, relatively rotatable grinding plates disposed in grinding relationship within said chamber, a spout on said chamber, means associated with said spout for providing a radial extension of said spout, means within said spout and said radial extension for guiding ground stock from said chamber, and means provided in said spout and said radial extension for admitting air to said chamber through said spout.

2. In an attrition mill comprising in combination, wall means forming a grinding chamber, relatively rotatable grinding plates disposed in grinding relationship within said chamber. a spout on said chamber, means for providing a radial extension oi said spout, partition means circumferentially spaced within said spout and said radial extension, a main partition of said partition means adapted to guide ground stock from said chamber, and an admission partition of said partition means associated with said grinding chamber for admitting air thereto.

3. In an attrition mill comprising in combination, wall means substantially formed by an arcuate wall and tangential converged portions, relatively rotatable grinding plates disposed in grinding relationship within said wall means, side extensions substantially extending said convcrged portions, a main partition spaced substantially parallel to one of said side extensions, an admission partition spaced substantially parallel to the other of said side extensions, said partitions and said side extensions forming interchangeably with said converged portions in accordance with the direction of rotation of the grinding plates, a stock discharge passage and an air admission passage respectively.

4. In an attrition mill comprising in combination, wall means forming a, grinding chamber, relatively rotatable grinding plates disposed in grinding relationship within said chamber, a spout on said chamber, radial extended means for said spout, a main partition spaced substantially parallel to one of said radial extended means for effectively guiding ground stock from said grinding chamber, an admission partition secured to said main partition and spaced substantially parallel to the other of said radial extended means ior admitting air to said grinding chamber, and an arcuate partition secured to said main and said admission partition for guiding ground stock into said admitted air.

5. In an attrition mill comprising in combination, Wall means substantially formed by an arplates, a, main partition secured to said upper.

and lower plates and spaced substantially parallel to one of said side extensions, said main partition forming with its said parallel side extension.

a discharge passage for guiding ground stock from said grinding plates, an admission partition secured to said upper and lower plates, and to said main partition at a point intermediate its ends,

and spaced substantially parallel to the otherV of said side extensions, said admission partition forming with its said parallel side extension an admission passage for admitting air therethrough, and an arcuate partition secured to said upper and lower plates and said main and admission partitions, for eiectively guiding ground stock into said air leaving said admission passage.

6. In an attrition mill comprising in combination, wall means substantially formed by an arcuate wall dening a grinding chamber, and tangential portions converging into a spout, a pair of grinding plates disposed within said chamber, means for rotatably driving one of said plates relative to the other of said plates, a plurality of fan blades radially secured to the underside of said rotating plate for aspirating air to said chamber, side extensions, one of said side extensions forming a continuous wall substantially extending one oi said tangential portions, the other of said side extensions forming a perforated wall substantially extending the other of said side extensions, upper and lower plates forming with said side extensions a detachable spout receivable within said iirst mentioned spout, a main partition secured to said upper and lower plates and spaced substantially parallel to said continuous wall, said main partition and said continuous wall forming a discharge passage essentially tangential to the periphery of said grinding plates for guiding ground stock from said grinding chamber, an admission partition secured to said upper and lower plates, and to said main partition at a point intermediate its ends, and spaced substantially parallel to said perforated wall to form therewith an admission passage essentially tangential to the periphery of said grinding plates for admitting air to be aspirated to said grinding chamber, and an arcuate partition secured to the inner ends of said main and admission partitions in diverging relationship with the outer circumference of said grinding plates, for guiding ground stock into the stream of incoming air.

7. In the structure of claim 6 reversible water jets positioned within said grinding chamber in accordance with the rotational direction of said rotatable plate, a xed water jet tangentially secured to said perforated wall, and a portion of said main partition extending in proximity to the periphery of said grinding plates.

8. In an attrition mill, a casing formed to define a grinding chamber having wall means with an arcuate portion, said wall means having converging tangential portions extending from said arcuate portion to dene a peripheral opening in said casing, a pair of relatively rotatable grinding disks disposed in said grinding chamber in radially spaced relation relative to said wall means, partition means connected to said casing and extending between said tan- REFERENCES CITED The following references are of record in the le of this patent:

Number UNITED STATES PATENTS Name Date Hobler Dec. 17, 1889 Marquardt Nov. 19, 1912 Beach May 30, 1916 Wear et a1 Mar. 20, 1917 McCool Oct. 2, 1917 Quehl Jan. 19, 1937 Brant Aug. 16. 1949

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