US3546821A

US3546821A - Vibratory finishing,grinding and deburring mills

Info

Publication number: US3546821A
Application number: US702970A
Authority: US
Inventors: John R Strom
Original assignee: Sweco Inc
Current assignee: Sweco Inc
Priority date: 1968-02-05
Filing date: 1968-02-05
Publication date: 1970-12-15
Anticipated expiration: 1987-12-15

Description

Dec. 15, 1970 R-STRQM 3,546,821

VIBRATING FINISHING, GRINDING AND DEBURRING MILLS Filed Feb. 5. 1968 3 Sheets-Sheet 2 INVENTOR JQ/ /A/ 6 5750 14 BY I 4 4 N v %4/ 424 M1 Q Q f ATTOEA/EV J. R. STROM 3,546, VIBRATING FINISHING, GRINDING AND DEBURRING MILLS Dec. 15, 1970 5 Sheets-Sheet 5 Filed Feb.

C R W O n N M w V 7 W5 1 7 A M w H u m a. 0 Y w B Unite States atent 3,546,821 VIBRATORY FINISHING, GRINDING AND DEBURRING MILLS John R. Strom, Fullerton, Califl, assignor to Sweco, Inc., Los Angeles, Calif., a corporation of California Continuation-impart of application Ser. No. 631,468, Apr. 17, 1967. This application Feb. 5, 1968, Ser. No. 702,970

Int. Cl. B02c 17/14; B24b 31/06 US. Cl. 51-163 11 Claims ABSTRACT OF THE DISCLOSURE A vibratory finishing apparatus having a generally toroidal finishing bowl in which a charge of parts to be finished and a finishing media are subject to vibration in the presence of an aqueous liquid, the apparatus having drain means for withdrawing liquid from the container, means for maintaining the liquid level in the container with the means for varying and maintaining the liquid level disposed above the drain means.

This invention relates to vibratory grinding, finishing and deburring mills in wihch a material to be operated on is contacted with a finishing or grinding media in a vibrating environment. More particularly, this application relates to apparatus and method for maintaining a fixed liquid level in such a mill.

This application is a continuation in part of my prior, co-pending application, Ser. No. 631,468, filed Apr. 17, 1967, now abandoned.

Vibratory finishing vessels in which a charge of relatively abrasive media is caused to operate on a part to be finished are known in the art and illustrated by such U.S. Pats. as 3,100,088; 3,266,739; 3,268,177 and 3,161,- 993. These may consist of a generally toroidal bowl in which the parts and media are caused to vibrate in order to finish or deburr the parts.

In one embodiment of such a device, a toroidal vessel or bowl is charged with the parts and media and vibrations are imparted to the vessel by virtue of a vertically mounted motor having eccentric weights at the top and bottom of the motor shaft. In such a device, the motor and bowl assembly are isolated from the surroundings by a ring of springs which attach the vessel and motor assembly to a base in such a manner that vibrations are not transmitted to the base. The top and bottom eccentric Weights are so arranged that the angle between them can be pre-set and the quantity of weight attached to the top and bottom eccentrics (lead angle) and weight quantity enables the operator of such a device to set the machine for a given charge of parts and media to obtain a given motion of the machine.

In addition to the parts and media, the machine is usually charged with a liquid which aids in the finishing operation. The liquid employed is usually aqueous and contains various soluble and non-soluble additives, depending on the particular finishing operation. When additives are used, they are ordinarily consumed during the fishing operation and the aqueous liquid becomes contaminated with fine particles caused by the degradation of the media and the finishing of the parts.

The particular motion imparted to the machine by virtue of the lead angle setting and the quantity of weights will vary in the vessel unless there is provision for maintaining the liqud level constant in the machine during the removal of the aqueous solution and the addition of fresh solution to the machine. The liquid is ordinarily added through an ordinary pipe header or spray device to the top of the finishing charge and old liquid is removed through a drain port in the body or near the bottom of the vessel. When accomplished in such a manner, the liquid level in the finishing mill constantly varies and causes a change in the vibratory motion imparted to the parts and media.

Application Ser. No. 631,468, filed Apr. 17, 1967, by John R. Strom, assigned to the. assignee of the present application (and now abandoned), discloses a device which accomplishes the maintaining of a constant liquid level in the machine during the removal of the aqueous solution and the addition of fresh solution to the machine.

In such application, the device as disclosed employs a drain receiving channel from which the liquid level controlling means, comprised in part of a flexible pipe, descends vertically and from a U-shaped bend portion ascends vertically.

Because the U-shaped bend portion is disposed below the drain assembly, fine particles in the machine which pass through the drain port tend to settle in the U-shaped bend, ultimately clogging the flexible pipe, thereby requiring periodic cleaning to remove the settled fine particles to prevent malfunction of the device.

It is therefore an Object of this invention to provide an improved vibratory finishing, grinding or deburring apparatus in which the liquid level can be maintained at a constant level.

It is a further object of this invention to provide such a device in which the liquid level existing during operations can be maintained at a predetermined, but variable, level.

It is still a further object of this invention to provide such a device in which pre-selection of the liquid level can be accomplished at infinitely varying levels of the finishing.

A still further object of this invention is to provide such a device in which clogging of the liquid level means is substantially eliminated.

In the drawings accompanying this specification:

FIG. 1 is a perspective view taken through 11 of FIG. 2 of a finishing mill showing the liquid level controlling means of this invention;

FIG. 2 is a section view taken through 22 of FIG. 1;

FIG. 3 is an isolated enlarged section view of the drain apparatus of this invention;

FIG. 4 is a partial perspective view of a finishing mill showing a portion of the liquid level controlling means of this invention; and

FIG. 5 is an isolated, enlarged partial section view of a portion the drain apparatus showing another embodiment of this invention.

The above and other objects of this invention are accomplished by a vibratory apparatus for finishing, polishing, deburring or grinding which comprises a base, a container for receiving media, liquid and parts to be finished, the container forming a channel, means for resiliently mounting the container on the base, vibratory means for imparting relatively high frequency vibrations to the container, drain means for withdrawing liquid from the container, means for maintaining the liquid 111 the container at a constant level and means for varying the liquid level in the container, the means for varying and maintaining the liquid level positioned above the drain means.

The vibratory finishing apparatus as shown in FIG. 1 consists of a base 10 upon which is mounted a ring of springs 11 which support the vibratory finishing chamber 12 and vibratory apparatus which comprises a motor 13 and upper and lower

eccentric Weights

14 and 15 respectively. The motor 13 and its

eccentric weights

14 and 15 are mounted by means of the mounting brackets 16 to a cylindrical extension 17 of the center column 18 which, in

conjunction with the chamber, is supported on the ring of springs 11 and is reinforced by gusset plates 19 which project between the springs 11.

The finishing chamber 12, as shown in FIG. 1, is toroidal in cross-section and helical in configuration with an annular bottom and a wide diameter center post 18 which may be hollow as illustrated. That is, the bottom of the chamber 12 may be in the form of a helical ramp beginning at a low point and increasing in height around the diameter to an elevated termination point, thus in effect, forming a waterfall over which the charge of parts and media travels during the finishing operation.

In an alternate form, which is not illustrated, the toroidal finishing chamber may be constructed so that the bottom of the chamber 12 is at a constant elevation without the helical ramp and waterfall.

Mounted in a suitable manner to the upper periphery of the center column 18 is a cover 20 which consists of a cylindrical base 21 on the upper periphery of which is secured a dome-shaped cover 22.

The inner walls 23 of the finishing chamber 12 are lined with polyurethane or other suitable material which, during the vibratory operation, will minimize the wear of the parts (not shown) and media 24 as they contact the walls 23 of the chamber 12.

As shown in FIG. 2, a vertical weir or dam may be located at the upper level of the gradient plane of the chamber 12 whereby the weir 30 is parallel to the crosssection of the chamber 12 or radial with respect to the mill. Although not shown, the weir 30 may be of a type which is manually inserted into the chamber 12 or may be manually, automatically or semiautomatically raised from a provided opening (not shown) in the chamber bottom to its appropriate height.

In operation of the above-described finishing apparatus, parts and media, by virtue of the vibratory apparatus, are caused to precess in a circular direction, ascending the gradient plane around the chamber 12, as well as flow in a generally circular pattern from the center column 18 to the outside of the chamber 12 and back toward the center column 18, Thus, when the weir is elevated, as the material precesses around the chamber 12, it flows over the vertical weir 30 where finished parts may be separated from media 24. The action of the vertical dam or weir 30 is to create sufficient mass pressure to cause finished parts and media 24 to elevate to the height of the weir 30 and be conducted therefrom to a separation device (not shown).

The bottom of the finishing chamber 12 is provided with a drain assembly 31 (shown in detail in FIG. 3) which consists of a circular drain plate with a downward projecting conical wall 51; the lower periphery of which is provided with a circular flange 52. The drain plate 50 and the projecting conical wall 51 are inserted into a complementary opening in the bottom of the chamber 12 whereby the drain plate 50 is flush with the walls 53 of the opening in the chamber lining 54 and the top surface of the plate 50 flush with the contour of the mill chamber bottom. The horizontal circular flange 52 on the periphery of the conical wall 51 is affixed by bolting, spot welding, bonding or other suitable means to an L-shaped member 55 projecting downward from the wall 53 of the opening in the chamber lining 54.

An upper channel 56, defined by the vertical side wall '57, the slanting bottom wall 58 and the drain plate 50 with its conical walls 51, communicates with the finishing chamber 12 through the plurality of openings 59 provided in the drain plate '50.

Extending from the upper periphery of the side wall 57 is a circular flange 60 which is bolted, spot welded or otherwise secured in a suitable manner to the peripheral flange 61 of the conical wall 51. Interposed between the flanges 60 and 61 is a sealing ring 62 consisting of rubber or other suitable material.

An efliuent conduit 63, passing through and affixed in a suitable manner to the side wall 57 of the formed chan- 4 nel 56, communicates with such channel through the opening 64 in the conduit 63.

Disposed below the bottom wall 58 of the upper channel 56, and either aflixed thereto or pre-fabricated as an extension of the bottom wall 58, is a lower cylindrically shaped channel 65 consisting of bottom and side walls 66 and 67. The upper channel 56 communicates with the lower channel 65 through the opening 68.

Aflixed in a suitable manner to the bottom wall 66 0f the lower channel 65 is the drain pipe 69 which may be positioned vertically, or slanting as shown.

Extending vertically through the externally threaded hollow bolt 70 and further extending through the opening 68 is a piston 71. The hollow bolt 70, through which the piston 71 passes, is provided with an upper flanged portion 72, below the lower periphery of which is provided a circular seal 73 of rubber or other suitable material. The inner periphery of the upper portion of the flange 72 is likewise provided with a seal 74, The inner wall of the bolt 70 is lined with polyurethane or other suitable material which acts as a bearing 75, thus enabling vertical movement of the piston 71 through the bolt 70. The lower portion of the externally threaded bolt 70 which passes through the bottom wall 66 of the lower channel 65 is fitted with an internally threaded jam nut 76 which, upon tightening, constricts the upper peripheral flange 72 of the bolt 70, resulting in the circular seal rings 74 and 75 being snugly held against the piston 71. However, it is to be noted that any sealing means may be employed which suitably seals the bearing or other employed bearing assemblies through which the piston 71 passes.

Affixed in a suitable manner to the upper end of the piston 71 is a poppet valve 77 of slightly larger diameter than the diameter of the opening 68, thus enabling the opening 68 in the bottom plate 58 to be sealed by retracting the valve 77 against the peripheral wall of the opening 68 in the bottom plate 58. Rubber or other suitable elastic material placed on the peripheral edge 78 of the poppet valve 77 insures a tight seal of the opening 68 when the valve 77 is in its retracted or closed position.

The piston 71 may be actuated by an automatic, semiautomatic or manual actuating device. As shown in FIG. 3, the lower end of the piston 71 is provided with a clevis 79 from which an actuating arm 80 extends horizontally. The arm 80 extends through a bushing 81 in the support member 82, such member being affixed to or pre-fabricated as an extension from the wall 67 of the lower channel 65. The support member 82 and its contained bushing 81 acts as the fulcrum for the actuating arm 80.

As shown in FIG. 4, the arm 80 further extends the opening 83, lock plate support 84 and lock plates 85. The lock plate support 84 is aflixed to the mill shell wall 86 by bolts 87 which pass through the mill shell wall 86 and plate support 84, the end of such bolt being provided with an internally threaded nut 88. The outer side of the support 84 is provided with horizontal threads or teeth 89 which correspond to the teeth 90 provided on the lock plates 85. Therefore, when the lock plates are placed against the support 84 and secured thereto by the bolts 92 which pass through the bolt openings in the lock plates 85 and the vertically channeled openings 91, in the support 84, with their ends provided with a nut 93, the teeth 89 and in the support 84 and plate 85 prevent any vertical slippage of the plates 85 during the vibratory operation of the mill.

As best shown in FIG. 4, the lock plates 85 consist of symmetrical but separate upper and

lower plates

101 and 102, both of which are provided with a channel 103 to enable the actuating arm 80 to be placed in an upper channel resting or open position, or lower channel resting or closed position.

The vertical position of the lock plates 85, as generally indicated in FIG. 3, may be adjusted independently of each other by virtue of channel openings 91, FIG. 4, in the support 84 which enable the

plates

101 and 102, FIG. 4, and the bolt 92 which passes through such plates,

to be vertically raised or lowered in the channel openings 91 and secured thereto by tightening the nut 88.

By adjusting the

lock plates

101 and 102 which control the vertical displacement of the actuating arm 80, piston 71 and poppet valve 77, the opening 68 in the bottom wall 58 of the upper channel 56 may thus be controlled. It should be observed, however, that any actuating arm resting, locking or adjusting means may be employed which enables the vertical displacement of the poppet valve 71 to be controlled.

FIG. is a partial section view of the drain assembly of FIG. 3 showing an alternative means to actuate the piston.

As shown in FIG. 5, a vertically positioned air cylinder, generally indicated at 130, is employed to actuate the piston 131. Projecting from the upper end of the cylinder 130 is a hollow stud 132 which is externally threaded. The cylinder piston 131 passes through the stud. The cylinder is placed onto the drain apparatus whereby the stud projects upward through an opening 133 provided on the lower channels bottom wall 134 and through the opening 135 in the upper channels bottom wall 136 with the pistons upper terminal end disposed within the upper channel 137.

A hollow, internally threaded bushing 138, having a downwardly projecting flange 139 corresponding in diameter to the opening 133, fits over the piston 131 and is threadedly attached to the cylinders stud 132.

By tightening the bushing 138, the bushing and cylinder are drawn together against the interposed bottom wall, thus securing the cylinder in its vertical position. Threadedly attached to the upper terminal end of the piston is a poppet valve 140.

The cylinder 130 is fitted with an inlet and discharge means for raising and lowering the piston 131. To raise the piston 131 and poppet valve 140, air or other suitable fluid is admitted under pressure to a hose 141 at the lower end of the cylinder. As the piston and valve more upwardly, air is released from a hose 142 at the upper portion of the cylinder. When the piston and poppet valve are in their raised position, the upper channel 137 communicates with the lower channel 143 through the opening 135.

Conversely, to lower the piston and poppet valve, air under pressure is admitted through the hose 142 and released from the hose 141 so that the piston travels downwardly in the cylinder 130. When the piston and poppet valve are in their lowered position, the upper channel 137 is sealed from the lower channel 143 by virtue of the peripheral edge 144 of the valve 140 being drawn against the periphery of the opening 135'.

It should be observed that any type of fluid actuating means may be employed to actuate the piston 131 and poppet valve 140 in an upward and downward position.

As best shown in FIG. 3, the horizontal portion 110 of a 90 bend elbow pipe 111 passes through the mill shell wall 86 and is aflixed thereto by welding or other suitable means.

The horizontal portion 110 of the pipe 111 is disposed on a plane slightly above the plane of the conduit 63. The elbow 111 communicates with the conduit 63 through the flexible coupling 112, the ends of which are connected in a suitable manner to the efliuent pipe 63 and horizontal portion 110 of the elbow 111.

As shown in FIGS. 3 and 4, the upper portion 113 of the elbow 111, although parallel to the mill shell wall 86, is rotated at an angle other than perpendicular to a horizontal plane through the vibratory mill wall 86.

In FIGS. 1 and 4, a flexible pipe 114, aflixed in a suitable manner to the upper portion 113 of the elbow 111, ascends from such pipe, ultimately passing through a sleeve 115 which, by virtue of its formed bend, directs the pipe 114 downward. The end portion 116 of the flexible pipe 114 extends to a point lower than the elbow 111.

The U-shaped sleeve 115 is aflixed in suitable manner to a support bracket 117. The support bracket 117, FIG.

1, is slidably mounted on a vertical rod 118 which extends the vertical height of the vibratory mill with both ends of the rod 118 welded or otherwise aflixed to the mill wall 86. The slidably mounted bracket -117 may be secured at any vertical location upon the rod 118 by tightening the nut 119 provided on the bracket 117 for that purpose. It should be noted that the reason for rotation of the upper portion of the elbow 111 and for the rod 118 and elbow 111 to be adjacently located as shown in FIG. 4 is merely to prevent crimping of the flexible pipe 114 when it is raised or lowered to a desired height.

The upper portion of the flexible pipe 114, which is downwardly directed by the U-shaped sleeve 115, is provided with small holes 121 about its periphery. A splash shield 120, disposed below the holes 121, is welded or otherwise secured to the pipe.

It should be observed that the liquid level controlling device, as above described, may be constructed of metal, plastic or other suitable material which is impervious to liquid and will withstand the vibrations imparted by the vibratory apparatus and still enable the device to have a variable top level. Thus, the

flexible pipe

114 and 116 may, as an alternative, be a trombone type arrangement of concentric pipes so that the upper portion can slide over the lower portion to adjust the height.

Operation of the level controlling device of this invention is as follows:

Liquid in the chamber 12, FIG. 1, passes through the drain ports 31, FIG. 2, into the upper channel 56, FIG. 3. When it becomes necessary to drain liquid from the chamber 12, the poppet valve 77, FIG. 3, is placed in its open or raised position by moving the actuating rod into the lower lock plate 102, FIG. 4, thus enabling the liquid to pass from the upper channel 56 into the lower channnel 65 by virtue of the opening 68 in the bottom plate 58, such liquid ultimately being discharged from the drain pipe 69 which communicates with the lower channel 65.

Although the operation of the level controlling device of this invention is described, in part, as employing the manual actuating means to raise or lower the poppet valve 77 (FIG. 3), it is to be understood that a fluid actuating means of the type, for example, as previously described and shown in FIG. 5 may be employed to accomplish the raising and lowering of the valve.

When the device of this invention is employed to maintain the liquid level in the chamber 12, FIG. 1, the poppet valve 77, FIG. 3, is placed in its lowered or closed posi tion by moving the actuating arm 80 into the upper resting position on the upper lock plate 101, thus preventing liquid from passing into the lower chamber 65. The slidably mounted support bracket 117, FIG. 1, is positioned on the rod 118 and secured thereto by the nut 119 at the desired liquid level in the chamber 12. The finishing mill wall 86, adjacent and parallel to the rod 118, is calibrated (not shown) from the lowermost point of the chamber 12 to the uppermost point. Therefore, the bracket 117 may be moved upon the rod 118 to any accurately determinable height. The liquid in the chamber 12 passes through the openings 59, FIG. 3, in the drain plate 50 into the upper channel 56 whereupon, by virtue of the eflluent pipe 63, coupling 112 and elbow 111, it passes into flexible pipe 114. Adjustment of the support bracket 117 to diflferent heights raises or lowers the uppermost portion of the U-bend around the U-shaped sleeve to varying levels. The level of the sleeve 115 approximate- 1y determines the level of the liquid within the mill. However, there frequently will be a disparity between the level of the sleeve 115 and the liquid level within the mill due in part to the vibratory action of the mill and the relative surface tension of the media and water as well as the size and packing fraction of the media. In the embodiment of the vibratory finishing mill illustrated, in which the bottom of the finishing chamber is in the form of a helically ascending ramp, two drain assemblies 31 are provided because, due to the vibratory action of the mill and the surface tension between the mill and the aqueous fluid in the media when the mill is in operation, the liquid level varies throughout the helical incline of the chamber bottom, even though one would expect to find but a single liquid level in the chamber.

In the embodiment of the vibratory finishing mill in which the bottom of the finishing chamber is at a constant level, ordinarily only a single drain assembly and level control device need be provided. However, it is to be understood that it is within the purview of this invention to use one or a plurality of any desired number of liquid level control devices in the finishing mill.

When the liquid level in the chamber 12 is to be raised, the slidable clamp 117 is raised to a height above the liquid level in the chamber 12.

Generally, in the operation of a vibratory finishing mill, the empty mill is first charged with media and then with parts, the vibratory motor is actuated and the finishing operation begins. At the beginning of the cycle, the aqueous finishing liquid is gradually added to the mill and the sliding automatic level assembly is set at a pre-selected level. There is thus a gradual buildup of liquid in the finishing chamber to the point determined by the top of the U-shaped sleeve 115, provided that the poppet valve 77 remains closed to prevent draining of the liquid from the mill. Because the liquid level builds up slowly in the mill, siphoning of the liquid from the mill is ordinarily no problem due to the fact that the liquid level does not rise rapidly enough to completely fill the U-shaped sleeve 115. However, to prevent siphoning in the event of a rapid liquid surge in the liquid chamber, siphoning relief means such as those illustrated by the pipe openings 121 may be provided.

While particular embodiments of this invention have been shown and described, it is not intended to limit the same to the exact details of the construction set forth and it embraces such changes, modifications and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

I claim:

1. A vibratory mill comprising:

a base,

a container for receiving media and parts to be operated upon within said container, said container forming a channel having a bottom,

means resiliently mounting said container on said base,

vibratory means coupled with said container for imparting vibrations to said container,

drain means coupled with said bottom of said channel, said drain means comprising a member forming a first chamber having a first opening communicating with said bottom of said channel, said member having a drain opening and a selectively operable valve coupled between said chamber and said drain opening, said chamber having a third opening, and

means for maintaining a liquid in said channel at a constant level comprising tube means coupled with said third opening in said member and communicating with said chamber, the height of said tube means being selectively adjustable for maintaining said liquid level.

2. A mill as in claim 1 wherein:

said third opening in said member is disposed above said valve and said drain opening.

3. A mill as in claim 1 wherein:

said tube means comprises a tube extending upwardly from said chamber to a U-shaped portion thereof above said drain opening of said member, said tube extending downwardly from said U-shaped portion, said downwardly extending portion having a siphon relief opening therein communicating through said tube and a splash guard mounted on said tube at said siphon relief opening.

4. A mill as in claim 1 wherein:

said member comprises said first chamber and a second chamber, said second chamber communicating with said drain opening, said valve comprises a poppet valve for selectively allowing communication between said first and second chambers, and means coupled with said valve for enabling remote actuation thereof from the exterior of said mill.

5. A mill as in claim 4 wherein:

said means coupled with said valve comprises an actuating rod pivotally coupled with said member of said drain means, a first end of said rod being coupled with said valve, and a second end of said rod extending from a housing portion of said container and through a lock plate and terminating in a handle portion, said lock plate having support surfaces for retaining said rod in first and second positions for respectively retaining said valve in closed and open positions.

6. A vibratory mill comprising:

a base,

a container for receiving media and parts to be operated upon within said container, said container forming a channel having an inclined bottom,

means resiliently mounting said container on said base,

first and second drain means coupled with said channel at difierent elevations along said inclined bottom, and

first and second liquid level control means respectively coupled with said first and second drain means, each of said liquid level control means having a tube member adjustably coupled with its respective drain means and adjustable from the exterior of said mill for adjusting the level of liquid within said channel.

7. A vibratory mill comprising:

a base,

means resiliently mounting said container on said base,

drain means coupled with said bottom of said container, said drain means providing a first outlet and a second outlet, said drain means having a valve for controlling flow from the bottom of said channel to said second outlet, said second outlet serving as a drain for liquid in said channel, and

liquid level control means coupled with said drain means for controlling the level of liquid within said channel, said liquid level control means including tube means coupled with said first outlet of said drain means, said tube means having a U-shaped portion having a first end coupled with said first outlet and a second end terminating in an outlet tube, said outlet tube having a siphon relief opening through the wall thereof, and a splash guard mounted on said outlet tube adjacent said siphon relief opening.

-8. A mill as in claim 7 wherein:

said channel is substantially annular and the bottom thereof is substantially helical extending to an elevated termination point thereby defining at least first and second elevations for said bottom,

said drain means is mounted at a first elevation of said bottom, and

a second drain means is mounted at a second elevation of said bottom, and liquid level control means coupled with said second drain means for controlling the level of liquid within said channel in conjunction with said first named liquid level control means.

9. A mill as in claim 7 wherein:

said first outlet of said drain means communicates with a first chamber within said drain means which in turn communicates with said channel, said chamber having a bottom and a side, said first outlet being through said side of said chamber, and said U-shaped portion and first end thereof of said tube means all being positioned with respect to said bottom of said chamber to prevent settling of fine particles from said channel in said tube means.

10. A vibratory mill comprising:

a base,

means resiliently mounting said container on said base,

drain means coupled with said bottom of said container, said drain means comprising a member having a first chamber communicating with said channel through an opening in said bottom, said chamber having a control port, said member having a second chamber with an exit port and a selectively operable valve coupled between said chambers, said valve when opened allowing liquid to be drained from said channel through said valve and exit port, and

liquid level control means coupled with said drain means for controlling the level of liquid within said channel, said liquid level control means including tube means coupled with said control port of said member, said tube means extending upwardly from said drain means and being selectively positionable with respect to said drain means to select and determine the level of liquid within said channel, said control port and tube means being disposed such that fluid therein may be drained therefrom through said valve means and said exit port to prevent clogging of said tube means by the settling of fine particles from said channel in said tube means.

11. In a vibratory mill having a base, a container for receiving media, liquid and parts to be finished, said container forming a channel, means for resiliently mounting said container on said base, vibratory means for imparting relatively high frequency vibrations to said container, drain means for withdrawing liquid from said container, level control means for maintaining said liquid in said container at a selected level and means for varying said liquid level in said container, the improvement comprising, said drain means including a chamber communicating with said channel and a drain valve underlying said chamber, said level control means including tube means coupled with said drain means, said tube means including a first tube portion coupled with said chamber of said drain means and including a second movable tube portion communicating with said first tube portion for selecting the level of said liquid in said container, said second tube portion being mounted outside said container for selective up and down movement and being positioned above said chamber in said drain means for preventing particles from said channel from settling in and clogging said second tube portion.

References Cited UNITED STATES PATENTS 3,253,369 5/1966 Reichert 51--163 3,100,088 8/1963 Podmore 24l175 3,161,993 12/1964 Balz 51-l63 3,400,495 9/1968 Balz 24l-l75X THERON E. CONDON, Primary Examiner D. G. KELLY, Assistant Examiner US. Cl. X.R.