US2376722A - Mixing attachment - Google Patents

Description

y z, 1945. A. I. PODELL 2,376,722

MIXING ATTACHMENT Filed July 1, 1943 ABRAM I. PODELL INVENTOR 58 @ZL AXJM ATTORNEY Patented May 22, 1945 UNITED STATES PATENT OFFICE MIXING ATTACHMENT Abram I. Podell, New York, N. Y. Application July 1, 1943, Serial No. 492,994

6 Claims. (Cl. 259-403) This invention relates generally to the field of mixing and more particularly to a novel mixing attachment.

,In many vfields of industrial endeavor it is necessary in the course of manufacturing procedures to mix liquids with liquids of varying viscosities or to mix liquids with solids of varying densities and physical properties. Various stirring and/or tumbling methods are used requiring intricate and complicated machines. Many industries, however, require the mixing of ingredients which have been placed in tanks or vats and where the operation is not consistently repetitive so that it is necessary and desirable to utilize so-called mixing attachments which are portable and may be transferred from one tank, vat or open drum to another.

Prior art structures of the latter class have been open to the objection that owing to the orgam'z'ation and arrangement of the elements thereof it has been difiicult to reduce undesirable vibration with the result that elaborate clamping means havebeen required to secure the device to the rim or edge of the tank in which the mixing was being performed. In the mixing of certain relatively viscous liquids and the mixing of solids with liquids, the position of the mixing element with relation to the material in the tank and the tank itself is of importance. Prior art structures have provided means for adjusting the position of the mixing element, but by reason of thaarrangement of the parts of the device, these parts are under substantially continuous stress and in order to prevent the undesired displacement thereof relatively heavy and cumbersome clamping means have been needed. Furthermore, the vibration of such devices owing to the lack of balance between the various parts causes an undesirable shifting of the parts with relation to each other While the mixer is in operation so that more constant surveillance is necessary.

It is therefore one of the principal objects of the present invention to provide a mixing attachment of the class described in which by reason of the novel organization and inter-relation of the various elements thereof, relatively light clamping structures are neededto positively secure the mixing attachment to the tank and to relatively permanently secure the same in any adjusted position thereof.

A very important consideration with mixing attachments of the present class lies in the cost thereof, The average user of this class of device has use for a large number of them and the lower the cost thereof the more of them he may have in service with the same capital investment. By far the greater proportion of the materials which are mixed by this class of device are of a relatively heavy nature and most efilcient mixing is obtained when this is done at low speed. In order to romote flexibility and easy shifting from one job to another, it is desirable that the attachments be operated by electric motors. As is'well known'in the present art, low speed electric motors are relatively more expensive than high speed motors. This fact has been taken into consideration in the design of prior art mixers and the speed of the mixing element has been reduced by the use of gear trains. This construction is both noisy and expensive and requires care with regard to lubrication. In accordance with the present invention desired reduced speed of the mixing element is obtained by the use of sheaves and a belt and by the changing of the sheave sizes various desired low mixing speeds may be obtained.

In accordance with the present invention provision is made for proper covering of the sheavebelt construction so that they are protected from dirt and also from accidental contact With the operator thereby providing an important safety feature.

The importance of proper mixing speed cannot be over-emphasized in connection with the efficient use of devices of the class described. Depending, of course, upon the viscosity and other characteristics of the materials being mixed, it has been found that the higher the speed of rotation of the. mixing element or impeller, the slower the actual speed of mixing, as the mixing element or elements tend to push the material being mixed out to the edge of the tank where said material is spun around forming a vortex or pocket giving an illusion of mixing, but with a relatively reduced amount of actual mixing taking place. Tests were made by placing a pair of electrodes in the upper part of a tank and connected by wires to electric measuring in.- struments. The tank was filled with pure water to a. level equal to the level of said electrodes. Pure water is a relatively poor conductor of electricity. In the bottom of the tank there was submerged a bag of salt (sodium chloride). As the mixing proceeds the salt enters into solution with the water, thereby permitting an increased flow of electricity in the circuit with the measuring instruments. Tests were made at different speeds and it was found that substantially R. P. M. of the propeller or mixing element gave the best mixing speed. It was found that it actually took longer to mix at a higher speed than at a lower speed because at the higher speed certain materials do not have suflicient time to flow into the propellers for mixing. With the slower speed of rotation the mixing element actually beats the material which flows into the spaces between the blades.

High speed mixing is not only usually unsatisfactory for the reasons just described, but there is also an increase in cost to the user because the horse-power required to drive the mixing element increases substantially in the ratio of the cube of the increase in speed. Thus, doubling the diameter of a propeller increases its effective area four times. For example, assuming a five-inch propeller having an effective area of twenty-five square inches, when the diameter is increased to ten inches, the effective area increases to one hundred square inches. It would thus appear that increasing the effective area of the propeller would result in an increase of four times the amount of liquid mixed at the same speed of rotation of the propeller. With an increase in the diameter of the propeller the power requirement, however, is increased to the ratio of New H.P.]

Old H.P.

Thus, for example, if the five-inch propeller mentioned above required a one-quarter horse-power motor to rotate the same under a given load at a given speed, it would require thirty-two times the old H. P. or eight horse-power to drive the ten-inch propeller at the same speed. In accordance with the present construction the mixing speed is where possible and where dictated by the nature of the ingredients being mixed maintained at substantially 150 R. P. M. This enables the use of relatively large propellers or mixing elements with a relatively small motor. Better mixing is thus obtained at lower power cost.

Propellers operating within stationary cylinders as used in axial flow-pumps have been referred to a vortex free propellers and I have found that these operate efficiently as mixing elements. Large type stationary mixers are made with stationary casings around the propellers.

It is another object of the present invention to provide the desirable effects of said vortex free propellers by placing the casing or ring so a to be supported by and rotated with the propeller or mixing element and so as to be concentrically positioned with relation to the driving shaft of the propeller.

An advantage of this construction lies in the fact that so-called vortex free action is obtained in a portable mixing attachment and the casing or housing for the propeller need not be individually adjusted and separately attached to the tank a the device is shifted from tank to tank. Furthermore, since the cylinder or housing moves with the propeller tilting or positioning of the mixing element in the tank may be readily accomplished.

Another advantage of this construction lies in the fact that there is a lesser tendency of the mixing element when of the vortex free construction to pull air into the mixture. The incorporation of air in the mixture is sometimes undesirable and may, for example, be detrimental to certain mixtures of ink or waxes, etc. Positive movement of the mixture is obtained since the mixture flows through the spaces between the blades and not around their outermost points.

Another object herein lies in the provision of a device of the class described which by reason of the proper balancing and arrangement of the parts permits the same to be secured to tanks or vessels of relatively light construction without additionally reinforcing the edge thereof which supports the mixing attachment.

The underslung and offset position of the motor removes it from the path of fumes from the mixture which might have a harmful effect.

These objects and other ends and advantages will more fully appear in the progress of this disclosure and be pointed out in the appended claims.

In the drawing in which similar reference characters designate corresponding parts:

Figure 1 is a fragmentary right side elevational view, some of the parts being shown in section.

Figure 2 is a reduced top plan view partly broken away.

In accordance with the invention, the mixing attachment generally indicated by numeral d0 includes: a relatively stationary frame I I a relatively movable frame l2; a prime mover l3; speed changing and power transmission means l4; a guard element l5; a bearing [6; a main shaft IT; a mixing element shaft [8; and a mixing element l9.

The stationary frame ll includes a substantially fiat plate 20 having an arcuate slot 2 l. The frame H is preferably substantially inverted U- shape and includes arelatively short inner leg 22; a relatively long outer leg 23. The indentation between the legs 22 and 23 is provided with a reinforcing flange or saddle 24, which is adapted to engage with the upper edge 25 of the side wall 21 of a tank 26. The free end of the leg 22 is provided with a tapped orifice 28 within which is threadedly engaged the shank 29 of a clamping screw 30. The rear end of the screw 30 is provided with a head 3| having an orifice transversely disposed with relation to the axis of the screw 30 and within which is slidably positioned a handle 32. Rotation of the screw 30 moves the clamping head 33 toward or away from the opposite portion of the saddle 24. The leg 23 adjacent the lower 'free end thereof is provided with a horizontally disposed orifice Within which is disposed an axle 34 which serves to pivotally mount the frame I2.

The frame I2 is of irregular configuration best seen in the drawing and includes a substantially vertical member 35 having a broadened motor platform 36 integral therewith. The member 35 is preferably substantially T-shaped in section as best seen in Figure The lower end of the member 35 is provided with a horizontally disposed orifice which is penetrated by the axle 34. Suitable means may be employed for preventing undesired separation of the lower end of the member 35 and the leg 23, as for example, the washer and cotter-pin structure shown. It may be noted at this point that the pivotal connection between the frames II and I2 formed by the axle 34 is substantially below the centers of gravity of the portions of the structure integrated with the frame 12 and located at either side of a vertical plane passing through said axle. The upper end of the member 35 is provided with a pedestal portion 3'! which is disposed at substantially right angles with relation to the member 35 and is adapted to have detachably secured thereto a guard I in any suitable manner as forexample,

by theuse of the bolts 38.

' Disposed between the pedestal 31 and the lower endof the member 35 is a transverse framemember 39. The lower portion of the frame member 39 may have a reinforcing rib 46 and adjacent the outer end, said rib may be enlarged to have a reinforced orifice which is penetrated by a bolt and wing-nut 4|. The bolt penetrates the slot 2|.as well, so that upon tightening of the wingnut, the left surface of the transverse frame mem ber- 39 may be securedto the right surface of the plate 26, at any pivotally disposed position of the frame I2 with relation to the frame I l limited by the bolt 4| 2|.

The upper portion of the transverse frame member 39 is provided with a threaded orifice in-which is engaged the screw 42 which forms part of the means for adjusting the position of the bearing I6 with relation to the frame I2. The upper'portion of the member 39 preferably has a relatively smooth upper surface and a pair of spaced and parallel side edges which are nestable within and between the downwardly extending guide flanges 43and 44 on the bearing exten sion 45. The bearing extension 45 is provided with-a centrally disposed slot46 which the screw 42 penetrates. Tightening of the screw 42 will fix the bearing I6 in any adjusted position with relation to the frame I2.

The'prim'e mover I3 may take the form of any suitable electric motor having a general correlation in weight and capacity to the rest of the device. Thus, with a motor of a given weight within a range to which the rest of the device is correlatedfshifting the extension 45 so thatv the parts may be balanced in weight with relation to the pivot axle 34, may be readily accomplished.

The motor I 3 may have the usual shaft 41 projecting upwardly therefrom and may have detachably secured to the end of said shaft a driving sheave 48.

The bearing I6 may be of any desired construction including a housin 49 in which are suitably secured at the upper and lower ends thereof orificed anti-friction blocks such as sintered bronze soaked in oil or may be provided at these points with well known ball or rollerbearings.

The main shaft I1 is journaled within the bearing I6 and may have axial movement thereof pre vented by suitable collars (not shown). The upper end of shaft I I has detachably secured thereto a sheave 56. The sheave 50 is connected to the sheave ,48 by a belt 5|. The lower end of the shaft I1 has secured thereto a coupling 52 which is adapted to receive in the lower portion thereof the mixing element shaft I 8. U

The shaft I8 has secured thereto an upper propeller 53 and a lower propeller 54. The upper propeller may be of any suitable construction the blades of which are set at an angle so that when they are rotated in thedirection of th arrow 55 the material to be mixed and which is disposed within the tank 26 will be elevated.

The lower propeller 54 has secured to the tips of the blades 56 thereof an open-ended hollow cylinder 51. It is desirable that the lower propeller 54 and the upper propeller 53 be detachably detachable to the shaft I8 so that their position with relation to each other and to the shaft may be adjusted to accommodate mixtures of varyin characteristics. By the use of the couplin 52 shafts corresponding to the shaft I8 of various lengths may be substituted so that the device I0 abutting against the ends of the slot.

may be utilized with tanks corresponding to the tank 26 of various sizes.

The cylinder 5'! acts as a shroud for the propeller 54 and permits this propeller to-act as a socalled vortex free propeller or axial flow pump enabling the propeller 54 to draw theheavier material which normally has a tendency to settle upon or near the bottom 58 of the tank .26. While the cylinder 51 is shown as being attached to the outer tips of the blades 56 of the propeller 54, where desired said cylindermay be independently connected by means of suitable spokes and hub (not shown) to the shaft I8.

It may thus be seen that a desirable mixin attachment structure has been disclosed which is easily portable and which is flexible in the utilization thereof so that the same may be varied to accommodate its use with tanks or mixtures of various characteristics. I

The saddle 24 is of such shape and size that same may be used on tanks of various upper edge thicknesses.

By manipulation of the bolt 42 the bearing extension 45 may be shifted horizontally, or longitudinally of the transverse member 39 to achieve a balance in weight relationship of the various parts with relation to the pivot axle 34. Furthermore, upon removal of the guard I5 the sheaves 48 and 50 may have other sheaves substituted therefore so that different speed ratios in the driven propellers 53 and 54 may be obtained. Short movements of the extension 45 may be made to tighten the belt5| sufiiciently for proper frictional engagement with said sheaves. Manipulation of the bolt and wing-nut structure 4| also permits proper balancing to be obtained and enables the user to swing the shaft it through an arc in the tank 26 so that the mosteffective engagement of the mixing element I9 (the propellers 53 and 54) with the mass in the tank may b obtained.

In view of the ready detachability of all of the parts, this construction permits the mixing attachment to be readily disassembled for compact storage and shipping and to be reassembled for use.

In view of the tilting feature by manipulation of the bolt and wingnut 4| it Will be obvious that a condition of absolute static balance throughout the entire range of tilt will not ordinarily occur but a substantial balance may be obtained 50 that there is relatively slight stress upon the bolt and wingnut structure 4| and even under conditions of considerable vibration the device will not ordinarily shift out of position once it has been set.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modification will occur to a person skilled in the art.

The size of the guard element I5 is determined generally by the largest size sheaves corresponding to the sheaves 48 and 50 which it is contemplated will be used in the operation of a given device I0, taking into consideration the selected extended position of the bearing I6 when the screw 42 abuts against the inner or forward end of the slot 46.

The smooth operation of the device I0 and freedom from undesirable shifting in position of the various parts is effected when the true center of gravity lies in a vertical plane which passes through the upper edge of the tank or other vessel corresponding to the tank 26, and to which the device is clamped, and that this is substantially the same vertical plane which passes.

through the axis of rotation of the axle 34, provides the proper balance;

It will be noted that not only does the positioning of the motor remove it from the path of fumes which arise or may arise from the material being mixed in the tank, but the weights are substantially balanced, and as the motor l3 and the propellers 53 and 54 are rotated about the axle 34 they each move away from said axle horizontally in arcuate paths of travel.

I claim:

1. A mixing attachment comprising: a stationary frame; a movable frame connected to said stationary frame at a point; a prime mover having a rotatable first axle, said prime mover being secured to said movable frame and laterally displaced from said point in a first direction; a mixing element having a rotatable second axle substantially parallel to said first axle, said second axle being slidably shiftably secured to said movable frame and laterally displaced from said point in a direction substantially opposite to that in which the prime mover is displaced; the Weight of the prime mover, the movable frame and the mixing element being such that the center of gravity thereof issubstantially disposed in a vertical plane passing through said point, whereby the effective center of gravity of the combined prime mover, movable frame and mixing element may be adjusted by the lateral movement substantially perpendicular to said second axle of said mixing element.

2. A mixing attachment for use with a tank comprising: a relatively stationary frame element; means on said stationary frame element for securing the same to said tank; a movable frame pivotally secured to said stationary frame; a prime mover and a mixing element secured to said movable frame at substantially opposite portions thereof; power transmission means connecting the prime mover and the mixing element, said prime mover and said mixing element being disposed with relation to a vertical plane passing through the point of pivotal inter-connection of the movable frame and the stationary frame a distance proportionate to the effective weight thereof so that said prime mover and said mixing element each exert a substantially equal leverage effect about said point of interconnection; and means to shift the position of the prime mover and the mixing element with relation to each other to compensate for differences in specific gravity of the mixture being treated.

3. A mixing attachment for use with a tank comprising: a relatively stationary frame element; means on said stationary frame element for securing the same to said tank; a movable frame pivotally secured to said stationary frame; a prime mover and a mixing element secured to said movable frame at substantially opposite portions thereof; power transmission means connecting the prime mover and the mixing element, said prime mover and said mixing element being disposed with relation to a vertical plane passing through the point of pivotal inter-connection of the movable frame and the stationary frame a distance proportionate to the effective weight thereof so that said prime mover and said mixing element each exert a substantially equal leverage effect about said point of interconnection; means to shift the position of the prime mover and the mixing element with relation to each other to compensate for differences in specific gravity of the mixture being treated; and means to adjustably clamp the movable frame in position with relation to the stationary frame. 4. A mixing attachment for use with a tank or othei vessel having an opening with a free upper edge, said attachment comprising: a relatively stationary frame element of substantially inverted U-shape forming an indentation between 21. pair of depending legs and adapted to engage said tank free edge, with one leg within the tank and the other leg outside of the tank; means on said stationary frame element for securing the same to said tank; a movable frame element pivotally secured to the said outer leg of the stationary frame element at a point substantially below the free edge of said tank and the greatest upper penetration of said indentation in the U-shape stationary frame element; a prime mover and a mixing element secured to said movable frame at substantially opposite portions thereof; a power transmission means connecting the prime mover and the mixing element, said prime mover and said mixing element being disposed on opposite sides of a vertical plane passing through the point of pivotal interconnection of the movable frame and the stationary frame; and means to inhibit relative movement between the stationary frame element and the movable frame element.

5. A device as claimed in claim 4 in which the means to shift the position of the prime I mover and the mixing element with relation to each other include a substantially transverse frame member on the movable frame and a bearing extension rotatably mounting the mixing element and slidably engaging said transverse frame member.

6. A device as claimed in claim 4 in which the means to shift the position of the prime mover, and the mixing element with relation to each other include a substantially transverse frame member on the movable frame and a bearing extension rotatably mounting the mixing element and slidably engaging said transverse frame member, and means to secure said bearing extension and said substantially transverse frame member in adjusted relative positions thereof.

ABRAM I. PODELL.

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