Grinding Mill

1. Field of the Invention

This invention relates to grinding mills, and is particularly concerned with mills of the type that are adapted for home use.

2. Prior Art

It has become increasingly popular to grind cereal grains, and the like, at home. This allows the home user to have freshly ground flour for use in baking, and the like, and to have freshly ground cereals and other desired products. A great many grinding devices have been developed for home use, and many of them are very suitable for grinding grains and the like. One such grinding mill is shown, for example, in U.S. Pat. No. 3,488,008, wherein grain to be milled is placed into a hopper on top of the machine and from there moves into a grinding chamber between a fixed grinding stone and a rotating grinding stone. The grain is ground into flour and is discharged peripherally from the grinding chamber before being entrained in air that is pulled into the housing by turbine blades and that is tangentially discharged. It has been found, however, that the mill of the aforesaid patent does not adequately cool the flour being ground and, the heat generated acts with the moisture in the grain to frequently ball up the grain such that it clogs the grain intake to the stones and causes flour to cake on the grinding surfaces of the stones. Additional clogging results from the straight discharge nozzle, which tends to allow the flour to settle as its velocity is decreased. In addition, the aforesaid mill is difficult to adjust to change the courseness of flour ground.

Principal objects of the present invention are to provide a mill that will better cool flour as it is ground; that will provide for easy adjustment between grinding stones so that the courseness of the ground flour can be set as desired; and that is less subject to clogging than turbine mills heretofore known.

Principal features of the invention include the central air feed whereby the rotating grinding stone and the flour being ground are constantly cooled during operation; the motor cooling obtained by providing air vents in the motor housing; and the adjustment means providing for adjustment of the motor shaft relative to the motor to thereby move the rotating grinding stone relative to the fixed grinding stone.

Still other features include plural adjustment means for setting grinding stone spacing and easily operated means for adjusting and locking such adjustment means.

Further objects and features of the invention will become apparent from the following detailed description taken together with the accompanying drawing, disclosing what is presently contemplated as being the best mode of the invention.

In the drawing:

FIG. 1 is a perspective view of the grinding mill of the invention;

FIG. 2, a vertical section view taken on the angled line 2--2 of FIG. 1;

FIG. 3, a bottom plan view of the baffle plate; and

FIG. 4, a bottom plan view of the adjustment plug and handle.

Referring now to the drawings:

In the illustrated preferred embodiment, the grinding mill 10, includes a motor housing 11, a flared skirt 12, pressed onto and glued or otherwise attached to a lower end of the motor housing and extending downwardly and outwardly therefrom, and a hopper 13.

A plurality of legs 14 are wedged between the lowermost portion of the motor housing 11 and the skirt 12 and the legs are preferably equally spaced around the housing. The wedging of the legs helps to prevent the skirt from moving up and down with respect to the housing and the legs are also securely glued or otherwise affixed to the housing.

A rubber foot 15 is attached to the bottom of each leg 14 to serve as a cushion and to prevent undesired sliding of the mill.

An electric motor 16 is positioned within the housing 11, with the motor shaft 17 projecting upwardly through a bearing 18 and an opening 19 in the top of the housing and downwardly through a bearing 20 in a boss 21 formed at the bottom of the housing.

Boss 21 is interiorly threaded to receive a threaded plug 22 on which the shaft 17 rests. A washer 23 on plug 22 surrounds the shaft 17 and supports another washer 24 that fits beneath the outer race of the bearing 20. As the plug 22 is threaded into and out of the boss 21 the motor shaft 17 is raised or lowered through the motor 16. Bearing 20 is simultaneously raised or lowered with the shaft 17, so that rotational movement of the inner race of the bearing with the shaft 17 is not affected by stone adjustment, even though such adjustment is performed while the mill is operated.

A baffle plate 24, having downwardly projecting, spaced bosses 25 rests on the top of the motor housing 11. Screws 26, inserted through the bosses and threaded into the top of the housing 11 secure the baffle plate to the motor housing and screws 27, spaced around the hopper 13 extend through the hopper and into the bosses 25 to secure the hopper to the baffle plate and with respect to the housing 11.

The hopper 13 includes an outer wall that extends downwardly at 28 below the top of the motor housing and that is spaced from the motor housing. A hopper plate 29 is press-fitted or otherwise affixed inside the hopper 13, a spaced distance above the baffle plate 24. The hopper plate 29 has a central grain feed opening 30 and is generally concave upwardly. A ring shaped non-rotating grinding stone 31 surrounds the grain feed opening 30 and is fixed to the bottom of the hopper plate. A concave grinding surface of the stone faces downwardly and the outer edge of the stone is then arranged to cooperate in a grinding relationship with the outer edge of a rotating grinding stone 32. The upper face of the rotating grinding stone provides a cooperating grinding surface and the outer edge thereof has radially extending slots (not shown), through which ground grain is peripherally discharged, as will be hereinafter further described.

The rotating grinding stone is glued or otherwise affixed to a backing member 33 that also has outwardly and vertically extending turbine blades 34 affixed thereto. The backing member 33 is fixed to a hollow shaft 34a that is telescoped over the end of motor shaft 17 and a cap 35 closes the end of the hollow shaft 34a to keep grain and the like from falling thereinto.

Motor shaft 17 and the hollow shaft 34a have keyways 36 and 37 respectively formed therein and a key 38 inserted into the keyways fixes the hollow shaft and the backing member, grinding stone and blades affixed thereto to the motor shaft 17 for rotation therewith.

A set screw 39 through the hollow shaft 34a and tightened into key 38 prevents vertical movement of the hollow shaft on the motor shaft.

As best seen in FIG. 3, baffle plate 24 has a central opening 40 therethrough and a wall 41 projecting downwardly therefrom to engagement with the top of the motor housing 11, FIG. 2. The wall 41 curves around the opening 40 and extends angularly outwardly from the opening to define a quadrant of the plate. The opening 40 is larger than the motor shaft 17 and the hollow shaft 34a. Air entering between the motor housing 11 and the hopper 13 and within the quadrant defined by wall 41 is passed upwardly through the opening 40 and into the space formed within the hopper 13 and between the baffle plate 24 and the hopper plate 29.

The space between the baffle plate 24 and the hopper plate 29, within the hopper 13 comprises a turbine chamber 45 within which the turbine blades 34 are rotated as the motor shaft is turned.

The air entering the turbine chamber 45, through the opening 40 passes beneath the backing member 33, cooling the backing member and the grinding stone attached thereto and is moved around the periphery of chamber 45. As the air is moved around the periphery of the chamber 45 it entrains the flour resulting from grain being dumped between the stones and ground as it is discharged from the slots radiating to the peripheries of the stones. The slotted stones, while not shown in detail, are well known, and any such commercially available stones can be used.

After the flour has been entrained, the air and flour are discharged from the chamber 45 through an opening 47 in the side wall of the hopper 13 and through a tangentially extending discharge spout 48. The spout 48 has a large inlet opening 49 (FIG. 2), and is smoothly and gradually tapered to a smaller outlet opening 50 (FIG. 1). This constantly decreasing opening of the discharge spout results in an increasing pressure as air and flour are forced therethrough. It has been found that the increasing pressure reduces the tendency of the spout to clog with flour being discharged therethrough.

The air moving across the backing member cools the rotating grinding stone and the grain being ground. This decreases stone wear and decreases clogging in the machine.

Air moving between the hopper 13 and motor housing 11 also circulates through openings 51, spaced around the upper end of motor housing 11, past the motor 16, and out openings 52 in the bottom of the motor housing. This air thus serves to cool the motor and to prolong the life thereof.

A handle 54 is attached to the bottom of plug 22 and extends outwardly therefrom, between a pair of legs 14, and beyond the flared skirt 12, where it is upturned at 55 to receive a lock member 56. The handle 54 is attached to plug 22 by screws 57 inserted through arcuate slots 58 (FIG. 4) and threaded into the plug.

The lock member 56 comprises a block that is mounted to slide up and down on the upturned portion 55 of handle 54. A screw 59 through the block and through a slot 60 in the upturned portion keeps the lock member 56 from coming off the handle.

The lock member has a face 61 that is curved to conform to the curvature of the skirt 12 and that is angled to correspond with the flare of the skirt. Thus, when the lock member is raised on the upturned portion 55 the handle is freely rotated between legs 14. Such rotation turns plug 22 and raises or lowers the motor shaft 17, as previously described and allows for precise adjustment of the distance between the fixed grinding stone 31, and the rotating grinding stone 32, carried by the motor shaft. If still further adjustment is required to properly position the stones, as for example may be necessary if the stones have become excessively worn, screws 57 can be loosened and the position of the handle 56 can be changed relative to plug 22. Thereafter, the screws 57 can be tightened and movement of the handle will again move plug 22 to change the position of the rotating grinding stone 32 relative to the fixed grinding stone 31.

When the handle 46 is set at a desired position it is securely locked in place merely by pushing down on the lock member to thereby wedge it tightly against the skirt.

In operation, grain or the like, is placed in the top of hopper 13, on top of hopper plate 29. The power cord 65 of the motor is plugged in and switch 66 is operated to start the motor. This rotates the motor shaft 17 and the grinding stone 32 and blades 34 attached thereto. The grain is gravity fed through opening 30 in the hopper plate and between the two stones. The ground flour is entrained by air entering chamber 46 from opening 40 and is discharged through discharge spout 40 to be caught in a bag or other suitable container.

The degree of courseness of the ground flour can be determined by setting of handle 54.

Although a preferred form of my invention has been herein disclosed, it is to be understood that the present disclosure is made by way of example and that variations are possible without departing from the subject matter coming within the scope of the following claims, which subject matter I regard as my invention.