US2284765A - Mixing apparatus - Google Patents

Description

Juile 2, 1942.

R. V PIERCE MIXING APPARATUS Filed Nov. 18, 1939 e .w P V a n ATTORNEY mounted in an upright position on legs 2.

Patented June 2, 1942 r UNITED STATES PATENT OFFICE MIXING APPARATUS Rex V.'Pierce, Long Beach, Calif., assignor, by

meme-assignments, to International Cementers, Inc., a corporation of Delaware Application November 18, 1939, Serial No. 305,119

3 Claims. (Cl. 259-178) This invention relates generally to mixing apparatus, and particularly to mechanical mixers of the type having rotating paddles or other agitating elements. The invention is directed to improvements in the paddle shaft assembly of such mixers, and has particular utility in mixers of the vertical cylinder type having a paddle shaft extending upwardly from the base of the mixer and rotatable about anupright axis by driving means disposed externally of the mixer.

A principal object of the invention is to provide mixing apparatus having an improved pad- .die shaft assembly including a shaft projecting through a wall of the mixing'chamber at a point normally below the level ofthe contents thereof,

and including novel and improved means for rotatably supporting the shaft and for effectively precluding leakage of fluid through the shaft opening in the wall of the mixing chamber.

A furtherobject of :theinvention is to provide mixing apparatus having a novel and improved paddle shaft assembly capable of being readily asembled and dismantled. 7

Other objects and advantages will be apparent from the following detailed description of a pre- Y ferred embodiment of the invention, reference being had to the accompanying drawing wherein:

Fig. 1 is a central vertical sectional view of a mixer constructed in accordance with the invenof illustrating the invention, a mixing apparatus particularly adapted for mixing solids and liquids,

such as cement and water A mixing'chamber l, preferably in the form of a cylinder having a closed lower end and an open upper end, is A throat piece, generally designated 3, is mounted prises spaced inner and outer cylindrical sleeve portions t and 5 and a downwardly converging funnel 6. The sleeve portions 4 and 5 are spaced apart to define an annular channel I open at its cured to the outer wall of the chamber, the eyebolts engaging bifurcated lugs iii secured to the outer sleeve 5. If desired, suitablepacking H may be disposed between the upper edge of the on the upper extremity of the cylinder and commountedon brackets 9welded or otherwise Se chamber l and the base of the annular channel I to provide a fluid-tight seal against leakage of fluid from thechamber at this point.

The funnel 6 converges downwardly toward the central axis of the chamber I to confine the enterlng stream of solids to the 'central portion of the chamber. The liquid ingredient of the mixture may be introduced into the chamber in any suitable manner; in the accompanying illustration there is shown a conduit l5 extending downwardly along the inner wall of the funnel 6 and terminating at its lower end in an outwardly deflected nozzle I6. Liquid may be supplied to the conduit through an elbow Ii secured to the upper end of the conduit and connected to a supply conduit (not shown). A discharge outlet 63 (Fig. 2) is provided in the side wall of the chamber through which the mixture is discharged.

Referring now to the paddle shaft assembly and its driving mechanism, it will be observed that a paddle shaft2l .is mounted in the mixing chamher for rotation about a vertical axis, and projects downwardly through the base of the chamber and into a gear housing 21 detachably secured to the under side of the base. A bevel ring gear 22 is detachably secured, as by cap screws 23, to a hub 24 keyed at 25 to the shaft It. The ring gear meshes with a bevel pinion 26 keyed to the inner end of a pinion shaft 21 rotatably mounted in the gear housing and having its opposite end projecting through the housing. A sprocket 28 or other driving element is secured to the pro jecting end of the pinion shaft, and is adapted to be connected to a source of power for rotating'the paddle shaft.

Inasmuch as the shaft opening in the base of the mixing chamber is submerged when the mixer is in use, it is essential that means be provided for preventing leakage of fluid from the chamber through the shaft opening and into the gear housing. This is particularly true if the mixer is being used to mix cement and water, as any contamination of the lubricant in the gear housing with cement slurry would obviously have a detrimental effect on thegearing and bearings.

In the present instance, leakage through the shaft opening is positively precluded'by the provision of a stationary sleeve or baffle 38 secured in fluid-tight relation to the base of the chamber and extending upwardly around the shaft 20 to a point above the maximum normal level of the contents of the chamber. As shown in the drawing, the lower end of the sleeve 30 is secured, as

by welding, to a hub 3| detachably secured, as by cap screws'32, to the base of the chamber. The

hub 3| is centered in the opening in the base so as to dispose the sleeve 30 in concentric relation to the shaft 26, and a bearing bushing 33 is provided between the upper ends of the sleeve and shaft. It is thus seen that the sleeve serves the dual purpose of excluding the fluid mixture from the shaft opening in the base, and of providing a bearing support for the upper end of the shaft 20,

It wil be observed that the upper end of the shaft 26 above the sleeve 36 is polygonal in shape at 34, and engages a polygonal socket in a hub member 35 secured to the shaft by a nut 36 engaging a threaded extension 31 on the shaft. The hub member is thus rigidly secured to the upper end of the shaft in non-rotative relation thereto. A paddle sleeve 40 is rigidly secured to the hub member, as by welding at 4 l, and extends downwardly therefrom in outer concentric relation to the stationary sleeve 30. A bearing bushing 42 is interposed between the lower extremity of the paddle sleeve 46 and the stationary sleeve 30, whereby the paddle sleeve is effectively journaled on the stationary sleeve at its lower end as well as having its upper end journaled in the stationary sleeve by the bushing 33 between the latter and the shaft 20. Adequate support is thus provided to resist any radial thrusts which might develop during rotation of the paddles mounted on the paddle sleeve 40.

As shown in Figs. 1 and 2, a plurality of paddles are secured, as by welding, to the paddle sleeve 40. In the present instance the paddles are arranged in three vertically spaced groups an upper group consisting of two diametrically opposed paddles 45, a central group consisting offour paddles 46 disposed at right angles to each other and with one pair thereof directly below the upper paddles 45, and a lower group of four paddles 41 disposed at right angles to each other and angularly offset from the paddles 45 and 46 at an angle of approximately 45, as most clearly shown in Fig. 2. It has been found that the foregoing arrangement of paddles affords rapid and thorough mixing and provides a balanced lateral thrust condition. In the preferred embodimentthe direction of rotation of the paddles is in a counter-clockwise direction as viewed in Fig. 2 and as indicated by the arrow P, and it will be observed that the leading edge of each of the paddles is inclined upwardly, whereby a downward thrust is exerted on the mixture, resulting in an upward thrust on the paddles and on the shaft 20.

The axial thrust to which the shaft 26 is subjected is transferred through the key 25 to the ring gear hub 24. The latter is journaled in the gear housing 2| between a lower bearing bushing 50 interposed between the hub and the gear housing, and an upper bearing bushing interposed between the hub and a thrust bracket 52. It will be observed that the bracket 52 is detachably secured to the base of the mixing chamber by'the same cap screws 32 which secure the hub 3| and the stationary sleeve 36 to the base, the cap screws extending through aligned openings in the bracket and the base plate and being threaded into the hub 3!. The upwardly directed axial thrust is absorbed by the upper bushing 5| and the bracket 52, while the lateral thrust developed by the bevel gearing is absorbed by a bearing bushing 53 between the gear housing and the portion of the shaft projecting below the hub 24.

The pinion shaft 21 forms part of a pinion shaft assembly which is insertible into and removable from the gear housing as a unit. The shaft is journaled in ball bearings 56 and 51, the outer races of which are mounted at opposite ends of a bearing sleeve 58. It will be observed that the outer bearing 51 is slidably mounted in the sleeve 58 and serves to sustain only radial thrust, whereas the inner bearing 56 is clamped against a shoulder 59 on the sleeve by a nut 6|], and sustains both radial thrust and the axial thrust developed by the bevel gearing. The bearing sleeve 58 is insertible into a bore 6| in the gear housing and is secured in place by a set screw 62. A cover plate 63 is mounted on the shaft and is bolted to the gear housing to provide a fully enclosed structure.

Suitable packing is provided at 65 to prevent leakage of lubricant from the housing along the shaft 21, and similar packing is provided at 66 to prevent egress of lubricant upwardly along the paddle shaft 20.

The foregoing construction provides a paddle shaft assembly and driving means therefor which may be readily assembled and dismantled. The mode of assembly is as follows:

The stationary sleeve 36 and its hub 3| are mounted in the shaft opening in the base, and the thrust bracket disposed in position on the under side of the base and the cap screws 32 inserted to clamp these elements together on opposite sides of the base plate. The paddle shaft 20, with the hub 24 and ring gear 22 keyed to the lower end thereof, is then inserted upwardly through the sleeve 30 from its lower end to position the upper bearing bushing 5| in abutting engagement with the lower surface of the thrust bracket 52. The paddle sleeve 40 is then inserted through the upper end of the mixing chamber (the throat piece 3 being removed) and is slipped downwardly over the shaft 20 and sleeve 36 to position the hub 35 over the squared upper end 34 of the shaft, and the nut 36 applied to the threaded projection 31 on the shaft to rigidly secure the paddle sleeve to the shaft. It will be understood that the bearing bushings 33 and 42 are mounted in their respective sleeves before assembly.

The pinion shaft assembly including the pinion shaft 27, bearings 56 and 51, and bearing sleeve 58, are inserted in the bore 6| in the gear housing and the latter is then attached to the under side of the mixer base plate by the cap screws 10 threadedly engaging a flange H welded to the base plate.

The throat piece 3 is then slipped downwardly over the upper end of the mixing chamber and secured in place by the eyebolts 8. It will be observed that downward movement of the throatpiece is limited by engagement of the upper edge of the chamber wall with the packing ll, rather than by engagement of the lower edge of the sleeve 5 with the upper surfaces of the brackets 9. By tightening the nuts on the eye-bolts 8, the packing is compressed between the upper edge of the chamber wall and the base of the channel I.

The gear housing may be partially filled with lubricant for the gearing and bearings therein, and a heavy lubricant may be forced into the annular spaces between the paddle sleeve 40, stationary sleeve 30, and shaft 20 through a lubricant fitting 15 to lubricate the bearings 33 and 42.

From the foregoing detailed description of a preferred embodiment of the invention, it will be apparent that a construction has been provided which affords adequate lateral support for V the paddle shaft and which positively prevents leakage of the contents of the mixing chamber into the gear housing. The relatively wide clamping faces on the hub 3| of the stationary sleeve 30 and on the thrust bracket 52 assure accurate alignment of the stationary sleeve with the paddle shaft. Also, by the provision of the bearing bushings 33 and 42, the paddle sleeve 40 is Jadequately supported against wobbling.

I claim:

1. Mixing apparatus comprising a mixing chamber having a shaft opening in a wall thereof; a shaft having a portion disposed exteriorly of said chamber and a portion extending through said opening and into said chamber one or more mixing elements secured to the inner portion of said shaft, said mixing elements subjecting said shaft to inwardly directed axial thrust during operation thereof; driving means on the exterior portion of said shaft; thrust bearing means disposed between said driving means and the outer wall of said chamber and comprising a stationary thrust plate detachably secured to the outer wall of said chamber adjacent said shaft opening, said thrust plate assuming said inwardly directed axial thrust; shaft supporting means detachably secured to the inner wall of said chamber adjacent said shaft opening and having supporting bearing engagement with said shaft ad: jacent its inner end; and a housing detachably secured to the outer wall of said chamber independently of said thrust plate and enclosing said driving means and thrust'plate.

2. Mixing apparatus as set forth in claim 1, in

which said shaft supporting means comprises a sleeve having a flange adjacent one end, means detachably securing said flange to the inner wall of said chamber to position said sleeve in concentric relation to said shaft, and a bearing between the distal ends of said sleeve and said shaft.

3. Mixing apparatus as set forth in claim 1,

in which said shaft supporting means comprises a sleeve having a flange adjacent one end and a hearing at the other end rotatably supporting the contiguous end of said shaft, and common means for detachably securing said flange to the inner wall of said chamber and for securing said thrust plate to the outer wall of said chamber.

REX V. PIERCE.

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