US1931555A - Grinding mill - Google Patents

Description

A. J. MOSLEY GRINDING MILL Get. 24, 1933.

2 Sheets-Sheet Filed Feb. 24. 1930 INV NTOR.

ATTORNEYS.

@ct. 24, 1933. A, J, MQSLEY 1,931,555

GRINDING MILL Filed Feb. 24, 1950 2 Sheets-Sheet 2 1 N VEN TOR.

A TTORNEYS.

Patented Oct. 24, 1933 UNITED STATES PATENT OFFICE Claims.

This invention relates to grinding mills and its primary object is to provide a mill of simple construction in which a material is ground to a predetermined fineness by mutual attrition of 5 its particles.

A further object is to produce the above stated result by centrifugal force upon the material while it is suspended in a current of air.

Another object is to determine the fineness to which the material is reduced in the operation of the mill by controlling the air current through the medium of a regulatable by-pass.

Another object is to provide means for separating the product of the mill into sizes by the air-current to which it was subjected in the mill, and still further objects reside in details of construction and novel arrangements and combinations of parts as will be brought out in the course of the following description.

In the accompanying drawings,

Figure 1 represents a sectional elevation of the apparatus,

Figure 2, a front elevation of the grinding mill, looking in the direction of the arrow A in Figure 1,

Figure 3, a section taken on the line 3-3, Figure 1, and

Figure 4, a section through the rotary element of the grinding mill showing a modification in the construction thereof.

Like characters of reference designate corresponding parts throughout the views.

The grinding mill comprises a stationary housing 5 having a cylindrical grinding chamber 5 6. At one end of the chamber is a feed-hopper 7, and its opposite end is through the medium of a tapering passage 8, connected with a circular fan-chamber 9. v

A shaft 10 extending through the axially alined chambers, carries within the grinding chamber, a cylindrical wheel 12 and within the fan chamber, a fan 13 of conventional construction.

The shaft is mounted for rotation in ball bearings 14 and 15 at the outer ends of the grinding I chamber and the fan chamber, and the shaft is, by means of a coupling 16, connected with the rotor of an electric motor 17.

The wheel in the grinding chamber consists, in its preferred form, of a hub 18 slidably mounted on the shaft by means of a key or feather 19, a rim 20 concentric to the hub and connected with the same by a number of spokes 21, and a heavy tire 22 preferably composed of soft rub her. The spokes of the wheel may be set at an angle as shown in Figure 3, to assist the passage through the wheel, of air-currents produced by the rotating fan. The grinding chamber may have a renewable liner 23 likewise made of soft rubber.

It is to be understood thatboth the tire of the wheel and the lining may be made of other wearresisting material such as hard steel.

The slidable wheel is at one side, engaged by a spring 24 that is coiled around the shaft 10 against a shoulder 25 of the same, and it is engaged at its opposite side by a sliding sleeve 26 that is mounted on the shaft by means of the before mentioned feather. The shaftis screw threaded at its end, and a nut 27 on the threaded portion of the shaft bears upon the outer end of the sleeve. It will be observed that by these means the wheel may be moved along the shaft to adjust its position within the grinding chamber.

At the end of the grinding chamber, opposite to its end-wa1l40, is an end-wall parallel to the other and composed of an annular baflle-plate 28 which, in the operation, serves to restrict the passage of the air current through the grinding space exteriorly of the wheel, which space constitutes the grinding chamber proper in the operation of the mill.

The central opening in the baille-plate constitutes the outlet for air and material from the grinding chamber and the plate is clamped between a shoulder 29 at the end of the grinding chamber, and the renewable lining 23, so that it is readily removed and replaced by a plate of different opening for the purpose of regulating the fineness of the product, as will hereinafter be more fully explained.

The heavy tire of the wheel may be divided into a number of separated blocks 30, as shown in Figure 4, but it is to be understood that these blocks do not function as hammers in the strict sense of the word, but merely aid in paddling or moving the material in its circular course within the grinding chamber.

The fan chamber has an outlet 31 which, by means of a conduit 32, is connected with the sizing element of the apparatus. I

The sizer, as shown, consists of a partially conical or funnel-shaped'housing 33 having, above its conical portion, an inlet 34 connected with the conduit, and at its lower end, a discharge spout 35.

Inside the conical portion, and in spaced relation to the wall thereof, is a correspondingly formed screen 36 which, at its lower end, has a discharge pipe 37 that extends through the spout 35.

Above the conical portion of the sizer is a vertical vent 38 for the escape of fine dust which, in the operation of the apparatus, may be caught in sacks or other suitable receptacles.

The material carried from the fan housing in the air currents constantly passing through the mill is divided into sizes in the sizer, the oversize passing through the screen into the annular space around the same to be discharged therefrom Ill) through thespout 35 and the undersize being discharged through the pipe 87 connected at the lower end of the screen. The oversize is delivered to the feed to be returned to the grinding mill and the undcrsize is conveyed to the storage bins.

The fine dust escaping through the vent at the top of the sizer is, as stated before, collected in sacks or other receptacles.

The air currents constantly passing through the sizer prevent clogging and keep the screen free from obstructive matter.

In the operation of the grinding mill, the rotating fan draws air entering the housing through a central opening 39 in the end-Wall thereof, in currents that are forced to pass constantly through the housing and the fan chamber to the outlet of the latter. It will be noted that the open-ended hollow wheel divides the current into two courses, one passing through the wheel and the other through the grinding chamber exteriorly thereof.

At the inside of the end plate 40 of the housing is a circular flange 41 surrounding the adjacent end of the wheel in spaced relation thereto, and this rim together with the annular bailie 28 controls the passage of air through the wheel.

By sliding the wheel along the shaft by rotation of the adjusting nut 27, the distances of its ends from the flange and the baffle are varied in inverse ratio and the current of air drawn through the wheel may thus be reduced or increased to any desired degree.

Variation of the air currents inside the wheel, changes the velocity and density of those in the grinding chamber in inverse proportion and inasmuch as the grinding action and the fineness to which the material is reduced are directly dependent on the velocity and density of the air in the grinding chamber, it will be evident that the adjustment of the wheel is the factor that determines the size to which the material is ground.

The grinding action may be regulated also by changing the baflle plate to one of diiferent opening. In fact, if a very course product is desired the bafile plate may be entirely omitted.

In explanation of the above, it will be apparent that a reduction of the velocity of the air currents through the grinding chamber, will cause the material to be subjected to the grinding action during a correspondingly longer period. The grinding action consists of mutual attrition of the particles in the material as they come in contact with each other.

The rotary movement of the wheel 12 causes the material entering the housing through the hopper '7, to be thrown outwardly by centrifugal force. The coarser matter will be thrown farther toward the circumference of the grinding chamber and its rotative velocity is correspondingly lessened to a point of comparative cessation of rotation. 1 The finer matter at and near the circumference of the wheel is compelled to follow the rotary motion of the same with the result that the masses of particles rotating at different velocities or/and within a relatively stationary mass, produce a grinding action between their contacting particles and thereby reduces them to a substantially uniform fineness.

The finer matter nearest the circumference of the rotating wheel is constantly drawn from the chamber by the air currents produced by the rotating fan, and replaced by coarser matter and the grinding operation is therefore, continuous subject, of course, to a continuous feed.

The regulation of the size to which the material is reduced, by axial adjustment of the wheel or by varying the outlet opening of the grinding chamber, permits of graduating the fineness of the product to any desired mesh.

What I claim and desire to secure by Letters Patent is:

1. In a grinding mill, a rotary wheel having an air-passage, a chamber having an end-wall provided with an air-inlet within a circular flange, an end-wall having a central outlet, and a grinding space around the wheel to receive material thrown outwardly by centrifugal force, the wheel extending partially into the flange and the wheel being capable of axial adjustment to vary its position relative to the flange and the outlet.

2. In a grinding mill, a rotary shaft, a wheel on the shaft, having an air-passage, a chamber having an end-wall provided with an outlet, and having a grinding space around the wheel to receive material thrown outwardly by centrifugal force, the wheel being slidable on the shaft to vary its position relative to the outlet, means for the supply of an air-current through the chamber, part of the current passing through the passage, and means for sliding adjustment of the wheel on the shaft, comprising an abutmentspring and a driving-member to move the wheel against the resistance of the spring.

3. In a grinding mill, a rotary shaft, a wheel on the shaft, having an air-passage, a chamber having an end-wall provided with an outlet, and having grinding space around the wheel to receive material thrown outwardly by centrifugal force, the wheel being slidable on the shaft to vary its position relative to the outlet, means for the supply of an air-current through the chamber, part of the current passing through the passage, and means for sliding adjustment of the wheel on the shaft, comprising a spring around the shaft, pressing on the wheel, and a nut on the shaft, bearing upon the wheel to move the same against the resistance of the spring.

4. A grinding mill comprising a rotary body adapted to throw material outwardly by centrifugal force, a housing providing a circumferentially closed annular grinding space around the body and having an inlet and an outlet for air at opposite sides of the body, the body having a passage for air between its sides, a fan connected with the outlet to draw a current of air through the grinding space and through the passage, and means to regulate the velocity of the current in the grinding space, by selective proportioning of the currents passing through the passage and the space.

5. A grinding mill comprising a rotary body adapted to throw material outwardly by centrifugal force, a housing providing a circumferentially closed annular grinding space around the body and having an inlet and an outlet for air at. opposite sides of the body, the body having a. passage for air between its sides, a fan connected with the outlet to draw a current of air through the grinding space and through the passage, and means to regulate the velocity of the current in the grinding space, by adjustment of the body relative to the inlet.

ALFRED J. MOSLEY.

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