US2727697A - Vibratory ball mills - Google Patents

Description

' 2 Sheets-Sheet 1 Filed Oct. 5, 1951 INVENTOR.

Dec. 20, 1955 w. K. STONE 2,727,697

VIBRATORY BALL MILLS Filed Oct. 5, 1951 2 Sheets-Sheet 2 IN V EN TOR.

VIBRATORY BALL MILLS,

Walter K. Stone, Kensington, Md., n ssig nor to The United States of America as represented by the Secretary of Commerce 6 Application October 5, 1951, Serial No. 250,007

7 Claims. c1L241--17s (Granted under Title 35, U. s. Code 1952 sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalty thereon in accordance with the provisions of a the act of March 3, 1883, as amended (45 Stat. 467 35 U. s. c. 45 v The present invention is concerned with improvements in vibratory ball mills of the type constructed by Dr. P. H. Hermans of Utrecht, Holland. In this type of mill a mass of hard balls is contained in a jar which is revolved but not normally rotated. The invention relates more specifically to a means for also rotating the jar containing the balls so as to prevent settlement to the bottom of the jar of the material to be ground by the movement of the balls.

In vibratory ball mills of the general type with which the present invention is concernedthe settlement of the material to be ground to the bottom. of the jar in which the grinding takes place has always presented a serious problem. In the original mill of this type it was necessary to periodically stop the mill, loosen the jar, rotate it, tighten it up and then start up the mill again. This, of course, is not practical in a commercialoperation. Other attempts to overcome this difficulty have been only partially successful and usually require a number of additional parts which greatly complicate the machine.

The primary object of the invention is to provide a vibratory ball mill in which the jar is automatically rotated.

Another object of the invention is to provide for automatic rotation of the jar without the use of a number of extra parts.

Another object of the invention is to obtain automatic rotation of the jar as a result of a very simple modification of the prior art device.

Other uses and advantages of the invention will become apparent upon reference to the specification and drawings.

Figure 1 is a cross-sectional view taken along the length of the machine.

Figure 2 is a sectional view taken along line 2-2 of Figure 1.

Figure 3 is a view taken along line 3-3 of Figure 1 showing the arrangement between the weight and the shaft.

Referring to Figures 1 and 2, the vibratory ball mill is mounted on the base plate 1. A motor 2 drives the shaft 3 through the flexible coupling 4. The far end of of the shaft 3 is journaled in the bearings 6 and 7 which are supported in the bearing housing 9. The bearings are kept properly spaced by means of the spacer 8. The suspension yoke 11 is clamped about the bearing housing and is drawn tight by means of the bolt 12. One side of the yoke is extended vertically upward and this vertical extension 13, together with the metal plate 14 form a jaw for clamping one end of the springs 16 and 17. The other ends of the springs 16 and 17 are clamped in the clamps 18 and 19 respectively which are in turn rigidly mounted on the base 1. This assembly, including the flexible coupling 4, allows the shaft 3 and all parts mounted on it to float on the springs 16 and 17 for reasons to be explained subsequently. The bearing housing and all parts mounted on it are not rigidly secured to the bearings and therefore are allowed horizontal motion limited only by the travel limit sleeve 21 which is riveted to the bearing housing. However, this allowance for horizontal movement is not necessary, and the bearing housing can be rigidly fastened to the bearings.

The free end of the shaft 3 is flattened on opposite sides so as to receive the eccentric weight 22 as shown in Figure 3. The upper portion of the weight has teeth 23 which contact the teeth 24 on the weight-adjusting plate 26. This arrangement in conjunction with the slot 40, in the weight 22, allows for adjustment of the weight with respect to the shaft 3.

The jar holder 27 is secured to theflange 25 of the weight housing 30 by means of the slip ring 28. The flange and the weight housing are merely a continuation of the piece forming the bearing housing 9. The outside diameter and thickness. of the flange 29 of the jar holder 27 are dimensioned so as to provide sufficient clearance relative to the weight housing 30 to permit rotation of the jar holder in the weight housing. The clearance between the horizontal face 31 of the jar holder and the face 35 of slip ring 28 determines the speed of rotation of the jar holder 27, for reasons to be explained below. Speeds from one to four revolutions per minute have been used.

A metal band 41 is clamped tightly about the jar 32 by means of the clamp 33. The band is then bolted to the jar holder 27 by means of the bolts 20.

The material to be ground and about 3700 small metal balls 39 which do the grinding are put into the jar 32. The motor 2 drives the shaft 3 and the eccentric weight 22 through the flexible coupling 4. Rotation of the weight about the axis of the shaft 3 and the restraining action of the springs 16 and 17 cause the weight and the shaft 3 to move in a complex path, which has a circular component, about the axis of revolution of the armature shaft 36 of the motor 2. The complex motion of the shaft 3 is transmitted to the weight and bearing housings 30 and 9, respectively, through the ball bearings 6 and 7. This high speed motion of the weight and bearing housings and therefore of the jar holder 27 and the jar 32 sets the balls in the jar into very rapid motion and causes a minimum of 100,000 collisions per second between the balls. This permits materials to be ground to sizes of a few microns in length or less.

This much of the action of the mill is old and well known in the art. However, when the mill was operated as originally built, which was with the jar holder bolted to the weight housing, the material being ground settled to the bottom of the jar making it desirable to periodically stop the mill, manually rotate the jar, and then start the mill up again. This is obviously inconvenient.

In the device of the present invention the rotation of the jar is accomplished by employing the principles of the standard internal differential gear. This is accomplished by the modification of the jar holder assembly. Formerly the jar holder was bolted to the weight housing. However, in the present device, as previously pointed out, the jar holder is secured to the weight housing by means of the slip ring 28. As a result of the internal differential gear action between the surface 31 of the jar holder flange 29 and the surface 35 of the slip ring 28, the circular component of the complex motion of the weight housing is transmitted to the jar holder and the jar holder is made to rotate in a direction opposite to the direction of rotation of the weight housing. The speed of rotation of the jar holder is dependent upon the relative diameters of the faces 31 and 35-and the speed of revolution of the weight housing.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be madeinconstructionand arrangement within the scope of my invention as defined in the appended claims.

I claim:

1. In a vibratory ball mill of the type comprising a container and-means for vibrating said-container including a shaft, means for rotating said shaft from one end thereof, an eccentric weight on the other end of said shaft. bearing means for supporting the last-mentioned end of said shaft, a bearing housing-spring supported for relatively free movement thereof-anda holder for said container being supported'by said bearing housing; the improvement comprising slip-ring means for providing an internal differentialfriction gear coupling between said holder and said bearing housing.

2. n a vibratory ball mill of the type comprising container and means for vibrating said-container including a shaft, means for rotating said shaft from one end thereof, an eccentric weight on the other end of said shaft, bearing means for supporting the last-mentioned end of said shaft, a bearing housing spring supported for relatively free movement thereof, a holder for said container, said holder having acircular flange which is supported by said bearing housing; the improvement comprising slip-ring means for providingan internal differential friction gear coupling between said flange and said bearing housing.

3. In a vibratory ball mill of the type comprising a container and means for vibrating said container including a shaft, means for rota-ting said shaft from one end thereof, an eccentric weight on the other end of said shaft, bearing means for supporting the last-mentioned end of said shaft, a bearing housing spring supported for relatively free movement thereof and 'a holder for said container, said holder having a circular flange which is supported by said bearing housing; the improvement comprising slip-ring means fastened to said bearing housing for providing an internal differentialfriction gear coupling between said flange and said bearing housing.

4. In a vibratory ball mill of the type comprising a container and means for vibrating said container including a shaft, means for rotating said shaft from one end thereof, an eccentric weight on the other end of said shaft,

bearing means for supporting the last-mentioned end of said shaft, a bearing housing spring supported for relatively free movement thereof and a holder for said container, said holder having a circular flange which is supported by said bearing housing; the improvement comprising a slip ring having a circular groove, said slip ring being fastened to said bearing housing, the circular groove receivingsaid-circular flange of-said holder, the diameter of the groove being larger than the outside diameter of said flange.

5. In a vibratory ball mill of the type comprising a container and means forvibrating said container including a shaft, means for rotating said shaft from one end thereof, an eccentric weight on the-other end of said shaft, bearing means for supporting the last mentioned end of said shaft, a bearing housing spring supported for relatively free movement thereof and a holder for said container having a flange and being supported by said bearing housing; the improvement comprising slip-ring means on said bearing housingv engaging said holder flange for providing an internal differential friction gear coupling-between said holder and said housing.

6. in a vibratory ball mill of the type comprising a container and means for vibrating said container including ashaft, means for rotating said shaft from one end thereof, an eccentricweight on the other end of said shaft, bearing means for supporting the last mentioned end of said shaft, a bearing housing having a flange spring supported for relatively free movement thereof and a holder for said container, said holder having acircular flange which is supportedby said bearing housing; the improve ment comprising the combination of slip-ring means having a first portion with a first internal diameter and a second portionwith a second internal diameter, said holder flange having an outer, diameter smaller than the diameter ofthe secondjportion of said slip-ring means, and means for retaining said holder flange between the bearing housing flange and the first portion of said slipring means.

7. In a vibratory ballmill of the type comprising a container and means for vibrating said container including a shaft, means for rotating said shaft from one end thereof, an eccentric weight on the other end of said shaft, a bearing housing spring supported for relatively free movementthereofand a holder for said container being supported by said bearing housing; and means for rotating said container comprising internal differential friction gear coupling means between said bearing housing and said container holder.

References Cited in the. file of this patent UNITED STATES PATENTS 2,171,115 Kiesskalt Aug. 29, 1939 2,469,484 Thiman May 10, 1949 FOREIGN PATENTS 596,712 Great Britain Jan. 9, 1948

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