US2637502A - Pocketed hammer rotor for pulverizing machines - Google Patents

Description

May 5, '1953 F. C. BOND POCKETED HAMMER ROTOR FOR PULVERIZING MACHINE Filed June '7, 1949 Patented May 5, 1953 POCKETED HAMMER ROTOR FOR PULVERIZING MACHINES Fred C. Bond, West Allis, Wis., assignor to Allis- Chalmers Manufacturin Wis., a corporation of g Company, Milwaukee, Delaware Application June 7, 1949, Serial No. 97,618

1 Claim. l

The present invention relates to pulverizing machines and more particularly t such machines as utilize rotating hammers, and the principal object of the invention is to provide new and improved pulverizing machines and hammers therefor.

Another object of this invention is to provide a pulverizing machine in which a maximum amount of the material is crushed on itself by impact, with only a relatively small amount of metal surfaces exposed.

Another object is to provide a pulverizing machine which utilizes the principle of centrifugal force in forming a hard, dense layer of the material being reduced such that the exposed surface of the layer forms an advancing impact surface.

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 more fully from' this specification and the accompanying drawing showing one embodiment of the invention and forming a part of this application, and all of these novel features are intended to be pointed out in the claim.

In the drawing:

Fig. 1 is a vertical sectional elevation taken through a pulverizing machine having the invention'applied thereto, taken on line I-I of Fig. 2;

Fig. 2 is a vertical sectional elevation of the machine shown in Fig. 1,- taken on the line II-II;

Fig. 3 is an enlarged top view of one of the hammers shown in Fig. 1; and

Fig. e is a sectional view of the hammer shown in Fig. 3, taken along line .IV-IV.

The pulverizer consists of a stepped shaft I0 mounted in bearings II which are supported by the stationary pulverizer casing or frame I2. A driving pulley I3 is fixed to one of the overhanging ends of the shaft I I), while a flywheel I4 is mounted on the opposite overhanging end thereof.

Suspension members I5 are provided for pivotally carrying the hammers as will appear. 'The members I5 have two parallel annular flanges extending outwardly from respective central hubs whi-chare keyed to the shaft I0. The new and improved hammers I9 have parallel Shanks 20 suspended from pins 2| which pass through the parallel flanges of the members I5. The hammers I9 are free to oscillate about the pins 2|, the pins 2| being fixed or locked to the respective hammer carrying members I5. It is to be understood that the means shown for adapting the 2 hammers I9 to be rotated by the rotor shaft I0 is preferred but that any suitable fastening m'eans may be used.

A hopper 22 is mounted on top of the casing I2 for feeding the material to be reduced into the reduction chamber 23 and a series of individual grate bars 24 are secured in the lower part of the casing I2, the use of such bars being optional depending on the degree of reduction desired.

The side wall of the casing I2 is lined with V-shaped channel members 25 shaped and arranged to form' pockets which ll With the material being reduced during operation such that the material being thrown by the hammers I9 is broken by impact against like material in the members 25. However, the lining of the side wall of the casing I2 may be of any suitable construction in `that the type of lining in itself bears no relation to the invention.

Although Fig. 1 shows four hammer members I9 secured to the suspension members I5 it is to be understood that any suitable number of hammers may be used. However, if only one hammer is used the shaft I0 will be unbalanced and for satisfactory operation this imbalance would have to be compensated for by attaching suitable Weights on the opposite side cf the suspension members I5.

In general, each hammer I9 is formed with a pocket 30 so constructed that when the shaft Il) is rotated at a suitable speed a layer of the material being reduced accumulates therein and the exposed surface of the layer forms an advancing impact surface 3| (see Fig. 1). The particular shape of the hammer I9 shown is a preferred embodiment but it is to be understood that certain deviations may be made from such shape without departing from the spirit and scope of the invention.

As shown in Fig. 1, the inside surface 32 of the radially outermost retaining wall 33 of the pocket 30 is normal to radial planes, radiating from and including the axis of the shaft I0 and passing through the wall 33, and the bottom' surface 34 of the pocket 30 lies generally in a radial plane. The inside surfaces of the pocket 3l] may be corrugated as shown in the drawing.

The theory or principle of the invention lies in constructing a pocket 30 in the hammer I9 in such a manner that the material accumulated therein, during operation, will not be displaced from the pocket 30 by the action of centrifugal force on such material. The material thus confined is subjected to the joint effects of centrifugal forces acting in a radially outward direction and the impaction of the material being reduced on the exposed surface 3l of the confined material such that the confined material in the pocket 30 is bonded into a hard, dense, tightly packed mass.

To utilize the above principle to the best advantage the material, accumulated in each hammer pocket 30, must be eifectively prevented from becoming displaced therefrom. The construction of the inside surface 32 of the retaining wall 33 normal to radial planes passing through the wall 33 thereby makes such surface 32 also normal to the direction in which the centrifugal forces urge the material accumulated such that the portions of the material adjacent the wall 32 tends to pack against it. As the magnitude of centrifugal force acting on a body revolving at a constant angular velocity increases with the distance such body is away from the axis. of revolution, in this case the axis of shaft i0, it is to be noted that the portion 36 of the material immediatelyA adjacent the surface 32 is exerting a greater force per unit area on the surface ,32 than the force per unit area exerted on that por tion 36 by material 3l adjacent thereto on the radially inward side. For that reason the high friction between the inside retaining surface 32 and the material adjacent that surface will notl be overcome.

The bottom surface 34 of the pocket and the perimeter 35 of the pocket opening are preferably in radial planes such that the tangential cross sectional area of the pocket diminishes in a radially inward direction. Therefore, not only is the force per unit area decreasing in the direction of the axis, as shown above, but also the tangential cross sectional area. As the friction between the particles of the material decreases from the retaining surface 32 in a radially inward direction, the radially inner portions of the material will tend to pack tightly against the radially outer portions but not force them out of the pocket. This tendency of the particles to pack together in an outwardly radial direction coupled with the impaction of the material being reduced on the exposed surface 3l of the accumulated material in the pocket 30 causes this accumulated material to be bonded into a hard, dense layer. When the exposed surface 3| of this layer becomes Worn in operation the portions so worn are continuously replaced by portions of the material being reduced. Therefore it will be apparent that there will 4 always be a layer of material retained in the pocket 3D.

From the foregoing it will be apparent to those skilled in the art that the illustrated embodiment of the invention provides new and improved pulverizing machines and hammers therefor, and accordingly accomplishes the objects of the invention. On the other hand, it will also be obvious to those skilled in the art that the illustrated embodiment of the invention may be variously changed and modied or features thereof singly or collectively, embodied in other combinations than those illustrated without departing from the spirit of the invention and accordingly the disclosure herein is illustrative only, and the invention is. not limited thereto.

It is claimed and desired to secure by Letters Patent:

A pulverizing machine, comprising, a casing, a hammer carrying member rotatably mounted in said casing, a hammer pivotally mounted on said member about an axis parallel to the axis of rotation of said member, said hammer having surfaces forming a pocket therein with an opening in a generally radial plane with respect to said axis of rotation for accumulating a layer of the material being reduced when said member is rotated about said axis such that the exposed surface of said layer forms an advancing impact surface, and at least some of said surfaces of said pocket being corrugated to resist displacement by centrifugal force of portions of said layer adjacent the corrugated portions of said surfaces.

FPUED C. BOND.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,144,102 rainard June 22, 1915 1,363,361 Seymour Dec. 28, 1920 1,405,151 Overstrom Jan. 31, 1922 1,816,408 State July 28, 1931 1,857,539 Hadsel May l0, 1932 1,916,190 Bowerman July 4, 1933 2,012,694 Runyan Aug. 27, 1935 2,207,194 Gruendler July 9, 1940 FOREIGN PATENTS Number Country Date f 388,337 Great Britain Feb. 23, 1933 '752,634 France July 24, 1933 234,182 Switzerland June 16, 1945

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