US2178636A - Grain grinder - Google Patents

Description

Nov. 3939. H. M. JOHNSTON 2,178,636

GRAIN GRINDER Filed Oct. 25, 1937 uwewrom HOWARD M- JOHNSTON A TTOR/VEX Patented Nov. 7, 1939 UNlT ED s'm'rs s ATENT OFFICE GRAIN GRINDER Application October 25,

2 Claims.

This invention relates to grinding or crushing machines for grains and the like andmore particularly to machines of the type which employ plates for grinding purposes.

In the grinding of hard grains, overfeeding frequently occurs and the grinding plates become heated up resulting in the caking of grain in the grooves. The grinding operation of the machine and its capacity are therefore adversely affected, and frequent inspection and adjustment are required. It has been proposed to associate a clutch with the feed worm arranged to release when pressure on the plates reaches a certain point. Such an arrangement, however, is complicated in construction and also calls for frequent adjustment to maintain. the desired capacity.

It is the object of. the present invention to provide a grinder having a resilient means associated with the feed worm whereby the feed Worm is yieldable in a longitudinal direction in response to certain pressures. Another object is to provide means for adjusting the tension of the resilient means whereby the yielding pressure of the worm may be varied for different types of grains.

The invention will be described with reference to the accompanying drawing, in which,

Figure 1 is a sectional elevation of the grinder, and

Figure 2 is a cross-section of the feed worm.

In the drawing, I is a feed hopper supported in a frame 2 of the grinder, 3 a feed worm positioned in the frame at the hopper outlet and carried by a driven shaft 4 suitably mounted in bearings 5 in the frame to be driven by means of pulley 6, and l and 8 the grinding plates also mounted in the frame I.

The grinding plates and their mounting in the frame are of usual construction and form no part of the present invention. Plate 1 is bolted to the frame as shown and plate 8 is bolted to a disc 9 keyed to the shaft 4 by means of key I which is mounted within hub 9'. The key I!) cooperates with a short groove II in the shaft whereby a slight axial movement of the disc is permitted. The disc is provided with a hub 9' against which a drum member l2 presses. The drum I2 is resiliently mounted on the frame 2 by means of bolts l3 and springs M in a manner commonly employed in the art. A cap is secured to the drum l2 and an'adjusting screw I6 is threaded axially through the cap. Mounted on the inner end of the screw is a bearing member I! having bearing engagement with a 1937, Serial No. 170,820

ball race 23 cooperating with a corresponding ball race 29 mounted on the reduced end-30 of the shaft 4. A pin 35 passing through the shaft maintains the ball races in position thereon. A locking nut i8 is provided for the screw 16. 6 When it is desired to adjust the machine for coarse grinding, the locking nut I8 is moved to permit turning of the screw 16, which is rotated in a counter-clockwise direction. Such rotation of the screw causes leftward movement thereof carrying with it the member I I out of engagement with ball race 28. As grinding begins, the clearance between member H and ball race 28 is taken up by axial movement to the left of shaft 4 with disc 9 under pressure of grain and a corresponding clearance effected thereby between plates 7 and 8. For fine grinding, the screw i6 is rotated in the reverse direction to reduce the clearance between the plates. It will be observed that disc 9 with plate 8, under a predetermined high pressure such as might be caused by entrance of a stone or like hard obstruction into the space between the plates, may move to the left against the action of springs M as permitted by its key connection It! with groove H in the shaft. Drum I2, cap l5, screw l6 and member I'l also all move leftwardly with plate 8, returning to their predetermined position under the action of springs I4 when the obstruction is dislodged.

The feed worm 3 is positioned in a substantially cylindrical housing [9 formed integral with the frame and is keyed to the shaft 4 for slidable axial movement therealong. As shown in Figure 2, keys 20 in the worm cooperate with grooves 2| in the shaft. One end of the worm bears against the hub 9' of the disc 9 and the other end is formed with a flange 22 of the same diameter as the worm. A spring 23 of substantially the same diameter as the worm is positioned in the rear end of the housing l9 and hears at one end on the flange 22 and at the other end on a disc 24 which is adjustably mounted on the shaft as by screws 25. The axial leftward thrust of spring 23 is much less than the combined rightward thrust of all of the springs [4.

The outlet of hopper I is provided with an inclined plate 26 to direct the grain onto the feed worm.

Grease cups 2! are provided for the various bearings.

In operation, with the plates suitably adjusted for the grain to be ground, the tension of the spring 23 is adjusted to the yielding pressure desired for the worm having regard to the na ture orthe grain to be ground; Whenjor any, reason excessive pressure occurs on the plates the worm slides rearwardly along the shaft to relieve the pressure, caused by obstructions and the like or by overfeeding. It should be stated that, due to the yieldable mounting of the worm, no overfeeding can result Thus the worm is made much larger in diameter than in the usual typeiof machines of the same power and size of grinding plates, and the machine therefore grinds a much greater amount of grain in the same space of time, The large diameter worm feeds the grain at a capacity rate to the plates at all times, any excesv ,sive pressure being absorbed by thespring 23.

It will be observed that, when excess pressure occurs in the 'g'rindingzone, the worm, while continuing to rotate with the shaft and without interruption of the grinding action, moves to the right (as shown in the drawing) relieving the pressure within the grinding zone, and thus damage is avoided.

It will be noted that the coils of spring 23 are of the same diameter and are inclined'in the same direction as the worm 3 and, since the spring revolves with the orm, the spring serves to carry out any particles of grain which may work past the flange 22 into the rearward portion of housing l9. Thus the spring maintains the latter portion of the housing free from accumulations of grain.-

I claim:

1. A grinder comprising a grinding chamber having a feed opening, a pairof grinding plates in thechamber, a feed-worm housing in alignment with said feed opening, a driving shaft "carrying one of said grinding plates and extemhng Such a pressure may be 7 ing adjacent said feed opening, a feedwo'rm keyedto the shaft for longitudinal movement therealong and normallypositioned in the latter end of the housing in alignment with said feed opening, a spring in the end of the housing remote from said hopper discharge and bearing upon the worm to urge the latter into said feed opening, said end ofsthe housing remote from; the hopper discharge being of sufiicient length to accommodate retraction of the feed worm .thereinto out, of alignment 'with the hopper discharge. p t t t 2. A grinder comprising a grinding chamber having a feedopening', a pair of grinding plates in the chamber, a cylindricalfeed worm Housing in axial alignment with said feed opening, a continuously driven shaft carrying one of said grinding plates and extending through said housing and grinding chamber, a hopper above said housing having a discharge opening into the end ofthehousing adjacent said feed opening,

a feed worm normally positioned in the latter end of the housing in alignment withtand ex:-

tending into said feed opening, said feed worm being keyed to the shaft for continuous rotation with it and movable longitudinally thereof, a springin the end of the housing remote from said hopper discharge and bearing upon the worm to urge the latter'into said feed opening, said end 01. the housing remote from the hopper discharge being of suflicient length to accommodate retraction of the feed worm thereinto out fof the feed opening and out of alignment with the hopperdischarger I g HOWARD MILTON J GHNSTON. I

through said housing and grlmhng chamber, a hopper above said housing having I v a discharge openinginto theend ofgthe hous+ I

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