US3698650A - Apparatus for grinding grain - Google Patents

Abstract

This invention generally relates to an apparatus familiarly known as hammermill used to grind grains, fodders, and gritty materials such as coal, glass and so on. This invention is a hammermill which has a high capacity and more uniform-sized output because of a plurality of counter-rotating hammers, as opposed to known uni-rotational hammermills.

Description

United States Patent Knight APPARATUS FOR GRINDING GRAIN [72] Inventor: Leslie Hugh Knight, c/o Robert Frayne and Co., Room 212, 1200 West Pender Street, Vancouver 1,

British Columbia, Canada [22] Filed: June 13, 1969 [21] Appl. No.: 833,104

[52] U.S. Cl ..241/51 [51] Int. Cl ..B02c 7/02 [58] Field of Search ..241/51, 49, 138, 154, 187,

[56] References Cited UNITED STATES PATENTS Danyluke ..241/138 51 Oct. 17,1972

2,774,543 12/1956 Keller et al. ..241/138 X Primary Exarriiner-Othell M. Simpson Attorney-Jerry B. Cesak [5 7] ABSTRACT This invention generally relates to an apparatus familiarly known as hammermill used to grind grains, fodders, and gritty materials such as coal, glass and so on. This invention is a hammermill which has a high capacity and more uniform-sized output because of a plurality'of counter-rotating hammers, as opposed to known uni-rotational hammermills.

1 Claim, 6 Drawing Figures PATENTEDBBI 11 I972 SHEET 1 0F 2 FIG. I

FIG. 2

PATENTED 17 4973 3,698,650

sum 2 [IF 2 APPARATUS FOR GRINDING GRAIN SUMMARY OF THE INVENTION The invention sets forth a novel apparatus using opposite rotating hammers that are attached to and rotate around a rotor which in turn is attached to a shaft and rotated by a power means.

Applicant has surprisingly discovered that the provision of counter-rotating power means which accordingly counterrotate the hammers substantially increases the output of production of this novel hammermill. The increase is at least 50 percent, and inmost cases 100 percent, of those materials produced by similar hammermills using comparable power means and similar sized interior accommodations. The hammermill herein described has two oppositely rotating rotors which is turn have hammers that are attached thereto and those hammers and rotors are held within screens which have predetermined diameters exceeding the diameter of the hammering apparatus. The screens have holes punched through them to allow an exit of various sizes of granular material that are crushed or pulverized therebetween.

The counter-rotating mechanism has been found to produce an increase in output heretofore not produced by uni-rotational hammermills that are well known in the art.

DESCRIPTION OF THE INVENTION The hammermill described as the invention in this application has many features that have heretofore not been included in or set forth in prior documents or prior art. It has been established by experimentation that this invention produces a higher quality and quantity of ground material than heretofore has been produced by the same input and the same hammermill size. The main object of this invention is the high capacity output of ground material accomplished. A further object is that the material that is ground or pulverized is of a particular uniform granular size rather than being ground into smaller sizes by hammermills familiarly known in the prior art. In other words, the hammermill as described herein produces less fines. A further object of this invention is that the material may have a gravity discharge or may be discharged by a suction fan from any external space surrounding the outside screen. Another object of this invention is the versatility of the screen removal and insertion. The screens that are held in position surrounding the hammers inside the interior space of the mill may be removed and inserted in a shorter time than has heretofore been possible. I

A further object of this invention is that slower speeds may be used than have normally been used in the past without having the hammermill plug-up in the vacant areas surrounding the screen as has happened in prior art hammermills. A further object is that the power or motor means that drives the respective hammers, rotors and shafts is supported on the same support members as the hammermill itself, thus providing a one unit frame. Further, it has been found that the vibration is limited with this one unit frame used during the operation of the hammermill. Another object is the low operating cost and the simplicity of operation of the device.

Other objects, features and advantages of the invention will be apparent from the following description when read with reference to the accompanying drawings. In the drawings, where like reference nu- 'merals denote corresponding parts throughout the several views:

FIG. 1 represents a partial sectional view of the mill and shows the counter-rotating motors on their respective sides;

FIG. 2 is a sectional view showing the interior of the mill, that view taken along lines 2-2 in FIG. 1;

FIG. 3 is a side view of the rotor having two of the regular four hammers shown attached thereto;

FIG. 4 is a sectional view showing a shaft with a typical rotor having three hammers spaced on one side of the rotor;

FIG. 5 shows a hammer separated from the rotor;- and FIG. 6 shows an attachmentthat holds the screen in place within the interior of the hammermill.

Having discussed the various figures, the details will now be explained, using like reference numerals for like parts.

FIG. 1 shows motors l and 2 which are provided with shafts 6 and 5- respectively. Rotor 7 is attached to either shaft 5 or 6 by means of a keyset and thus rotor 7 is prevented from rotating about shafts 5 and 6 respectively. Hammer 8 is swingably attached to rotor 7 and may rotate around a pin which is inserted through the long fingers of rotor 7 and prevents hammer 8 from moving in a radial direction when therotor and respective hammers rotate about shafts 5 and 6. Frame 3 provides a solid base for motors 1 and 2 and completely surrounds the milling or grinding part of the hammermill. Door 4 is a hinged door and opens in a horizontal direction. Door 4 is attached to frame 3 by means of a hinge and is hinged on one side of frame 3, and thus permits the motor 2, shaft 5, rotor 7, hammers 8 and door 4 to be opened away from and apart from rotor 7, shaft 6 and motor 1, and thus provides an easy and fast entrance into the interior of the hammermill when it is not in operation.

Entrance 11 provides for an entrance chute through which grain or other materials may be inserted into the mill when it is in operation. Magnet 12 may be inserted around entrance chute 11 on the bottom or sides of said chute 1 1; the magnet prevents any ferrous material from entering the mill and thus causing damage to the hammers or the screens respectively. Feeder 13 provides a variable flow of material into the mill and through entrance chute 11. Control panel 14 provides either an electrical control panel for the motors if they are electrical or the belt control if the hammermill is driven in a large mill by means of belts from another power source. Control panel 14, in the case of motors 1 and 2 being electrical, provides for a control of those motors and may also contain a switch for reversing the direction of rotation of motors 1 and 2 respectively.

Screens 15 in FIG. 2 provide for a change in the diameter of material that is to be ground; that diameter may be predetermined and thus the appropriate screen 15 may be inserted into the mill as desired. FIG. 2 displays the inside of the mill as shown along lines 2-2 in FIG. 1, thus provides an entrance chute l1 and subsequently provides for exits 21, 22, 23, or 24 which any one of these exits may provide a draft wherein air may be sucked through the inside of the mill and into any other exit direction. FIG. 3 provides a side view of the rotor when two of the regular four of hammers 8 are attached thereto. Shaft 6 is shown at the center having rotor 7 and hammers 8 respectively attached thereto. A key mechanism which is not shown in shaft 6 retains rotor 7 from moving with respect to shaft 6 either in a circular direction around shaft 6 or in a horizontal direction parallel to shaft 6, thereby rigidly holding the rotor 7 with respect to shaft 6. FIG. 4 shows a cross section through the rotor and shows hammers attached thereto, and is a cross sectional view of FIG. 3. FIG. 5 shows hammers 8 and hammer surfaces 9 and respectively. Each hammer surface 9 or 10 is at respective ends of hammer 8. Screen holder 17 permits screen to be removed in a fast manner. and thus provides for an efficient change of diameters in screens as desired for various dimensioned end products.

Having discussed the various parts of elements of the invention, the operation of it will now be explained. The materials that may be used or ground in the instant hammermill are discharged by feeder 13 into the confined space within screen 15. Motors 1 and 2 have separate shafts 6 and 5 respectively which are .in turn rigidly attached to rotor 7. The motors rotate in opposite directions thus providing the alleged increase in production. Shafts S and 6 are spaced apart from one another and are theoretically confined to a parallel position of each other abutting one another inside the interior space of the milling area. Hammers8 are attached to rotor 7 by means of a pin. Generally there are four sets of four hammers on each rotor thus providing a total of 32 hammers which are attached to two rotors which are in turn attached to two different shafts. The screens are of slightly larger diameter than that of the full diameter of rotor 7 and hammers 8 extending radially therefrom. Thus, when the respective motors are in operation and rotating in opposite directions the hammers 8 are extended to a limit which is less than the diameter of the screens which provide for an exit for the material that is being ground.

Hammermills, that have been known to this point in time, have rotated the hammers in one single direction; the invention herein described provides for opposite rotating hammers and rotors and thus has provided a novel device which increases the production over that of the prior art hammermill. The hammermill thus provides an economical use, in that it increases production and may be used until the hammers have been worn on both sides of their hammering ends. Thus, either of the hammer surfaces 9 or 10 may be worn on both sides by simply reversing the opposite rotating motors, and thus providing two sides of hammer surface wear without changing or dismantling the hammers in order to place them in a position so as to wear out one of the other four sides. It may be seen that two positions of the hammer will wear out each hammer; this feature provides for a minimum of changing the hammer position, whereas in prior art the hammer had to be changed four times in order to wear each end hammer surface out. The entrance draft means may be placed in any position shown by arrows 20 to 24 respectively. It has been found that the draft entrance means may be from the top, the sides or the bottom of the frame and the exit means may be also from the top, bottom or sides respectively. If the exit means is from the top, a fan, generally is required to provide the ground material with an exit force to impel it to another position away from the interior of the hammermill, but the counter rotation of the respective rotors and hammers provide for a minimum amount of plugging or settling of the ground material which has been a problem in prior art hammerrnills especially if the material was of a slightly moist or moistened condition. The power means may be an electrical motor or a belt mechanism and of course, in the case of a belt mechanism the belt may be simply twisted once to rotate the respective motors into a reversible direction.

The experimental data that has been accumulated from this novel hammermill provides that the rotors should be rotated in opposite directions and if this is accomplished the mill will increase the production over the production of the mill if the two rotors and respective hammers are rotated in the same direction. Thus it is mandatory that the respective rotors are rotated in opposite directions to fulfill the promise herein set forth in this invention.

It has been found that the hammers should be constructed of a hard steel preferably a steel known as 5160 STEEL and having a tungstan hard facing at the respective edges of those hammers. The screens are well known in the art, and the motors are of a 25 hp or similar to that electrical power output- The optimum I rotation is 3,600 r.p.m. There may be fewer or more than four hammers provided between the respective fingers of the rotors; however, it has been found that four provide a balance and less vibration than any other number of hammers. The feeder mechanisms, entrance drafts and exits are well known in the art and thus novelty is not claimed on those respective means. The rotor feeder is also well known in the art and provides for variable dry feeder through which the material passes. Also, it has been found, by experiment, that this hammermill reduces the amount of dust that is created by grinding material by use of the counter-rotating hammers and an exit forced-air fanning means.

I claim: I

1. In a hammer mill, the combination of a housing including a supporting base projecting in opposite directions from said housing, a foraminous drum mounted in the housing, a material inlet provided on the housing in communication with the interior of said drum, a pair of motors mounted on said supporting base at opposite sides of the housing, said motors having a pair of shafts which extend from opposite sides into thehousing and are coaxially disposed in said drum in close end-to-end relation, a pair of rotors secured to the respective shafts within said drum, said rotors being provided in the peripheral portions thereof with slots, and a set of strap-like hammers pivotally mounted in the slots of each of said rotors for limited swinging movement in the planes of rotor rotation, the foregoing being further characterized in that said motors drive the respective shafts and the respective ro- 5 tors in relatively opposite directions.

Claims (1)

1. In a hammer mill, the combination of a housing including a supporting base projecting in opposite directions from said housing, a foraminous drum mounted in the housing, a material inlet provided on the housing in communication with the interior of said drum, a pair of motors mounted on said supporting base at opposite sides of the housing, said motors having a pair of shafts which extend from opposite sides into the housing and are coaxially disposed in said drum in close end-to-end relation, a pair of rotors secured to the respective shafts within said drum, said rotors being provided in the peripheral portions thereof with slots, and a set of strap-like hammers pivotally mounted in the slots of each of said rotors for limited swinging movement in the planes of rotor rotation, the foregoing being further characterized in that said motors drive the respective shafts and the respective rotors in relatively opposite directions.

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