US2250838A - Mixing device - Google Patents

Description

July 29, 1941.

S. K. NESTER MIXING DEVICE Filed Dec. 19, 1939 INVENTOR SAMUEL l1. NESTER.

BY ATTORNEY of the elements in response Patented July 29, 1941 NT OFFICE 1 MIXING DEVICE Samuel K. Nester. Geneva, Inc., a corporation of New 7 Geneva Processes,

York

assignor to I ApplicationDccember 19, 193i), Serial No. 310,073 i '9 Claims. (cine- 105 My invention relates to mixers, beaters, grinders and similar apparatus for treating or agitatingliquids or material mixed with liquids and' particularly toconstructions having mixing or agitating elements operable at differentspeeds.

Various types of mixers, heaters and grinders have been designed heretofore for forming emulsions, grinding pigments, dissolving or dispersing solids and for otherpurposes wherein beating, grinding or agitat g members are positively driven at different speeds; However, such devices are frequently complicated and require continued adjustment to'vary the relative speed tion of the material undergoing treatment. Moreover, special and expensive bearings are frequently required to maintain" the mixing elements in proper relation and alignment.

to changes in condi- In accordance with my invention these objections to mixers and heaters of the prior-art are overcome and devices provided which are simple in construction and economical to produce and operate and which are automatically responsive to changes in the condition of the material undergoing treatment.

Devices embodying my invention are adapted for use in forming mixtures or emulsions of liquids; in grinding or mixing pigments, dyes or other materials suspended in a liquidmedium; in dissolving. suspending or dispersing solids in liquids, and in many other operations wherein a liquid medium is employed. However for simplicity in describing my invention all such devices are hereafter referred to as mixers and certain of the operating elements are referred to as mixing elements although their function in some instances may be primarily that of a grinding element, scraper or stirrer.

A characteristic feature of constructions embodying my invention resides in the use of a floating mixing element which is impositively driven through the action of material undergoing treatment so that as the viscosity or other properties of the material change during operation the speed and force with which said element is driven are correspondingly altered.

Another characteristic feature of my invention resides in novel bearing and aligning means employed for insuring proper operation of the mixing elements and the maintenance of such elements in the proper relation to each other.

One of the objects of my invention is to provide a novel type .ofv mixing device or the like which is simple in construction, economical to which the shaft 4 extends and produce and operate and adapted for usein the treatment of a wide variety of materials.

Another object of my invention is to provide a mixing device or the like having a plurality of mixing elements one of'which is positively driven and another of which is impositively driven.

A further object of my invention is-to provide a mixing device or the like with novel means for maintaining the-mixing elements in the desired cooperative relation.

A-specific object of my invention is to provide a mixing deviceor thelike with a floating-"mixing element impositively driven by the action of the material undergoing treatment. a r I These and other objects and features of my invention will appearfrom the following descrip tion thereof in which referenceis made to the figures of the accompanying drawing.

' In the drawing; v I

I Fig. 1 is a vertical sectional view through a typical mixing device embodying my invention, and 3 -Eig. 2 is a horizontal sectional view through .themixing device of Fig. 1, taken on theline 2-2 thereof. a In that form of my inventionillustrated in the drawing the mixi'ngdevice is provided with a high speedmixing element 2 secured'to a shaft 13 which in turn is connected to a motor 6 by a coupling 8. Alo'w speed mixing element I0 is rotatableaboutthe shaft 4 in the same direction as the element 2 but at a lower speed. An antifriction bearing ii serves to maintain the shaft 4 and the upper portion of the low speed mixing element in proper alignment while means on the lower portion of the element It] cooperate with the high speedmixing element 2 to provide a floating bearing for centering the lowerend of the low speed mixing element with respect to the element 2. I

The form ofthe high speed mixing element may be varied considerably to adapt the device for any. particular operation but as shown the element 2 is in the form of a disc having an outwardly inclined peripheral surface It and is provided with fins or impelling blades l6 secured to'the upper surface of the'disc to force material radially outward toward the surface l4 on rotation of the disc. 5 The low speed mixing element It also may be varied considerably for any preferred use of the device but preferably it is formed with a lower member l8 having a central opening 20 through into which the material being treated passes to the high speed mixing element during operation. The lower surface of the member i3 adjacent the opening 29 is inclined downwardly and outwardly and spaced from the upper face of the disc 2 to form a chamber for receiving material to be treated. The outer portion 22 of the lower surface of member I8 is substantially parallel to the surface M of the high speed mixing elements and is spaced only a short distance therefrom.

With this construction material entering the central opening 20 is impelled outward against the lower surface of the member I8 by the blades IS on rotation of the element 2. The material is thus forced between the spaced surfaces l4 and 22 of the mixing elements so that the low speed mixing element is raised slightly and caused to float or ride upon a film .of the material undergoing treatment and passing between the cooperating surfaces of the mixing elements. At the same time the material, being fluid, tends to distribute itself uniformly about the element 2 and betweenthe surfaces l4 and 22 centering the member IS with respect to the element 2. The material thereby functions as a floating bearing to maintain the surfaces l4 and 22 in the desired operative relation.

The material in contact with and located adjacent the surface I of the high speed mixing element tends to rotate therewith and so causes the low speed mixing element to rotate in the same direction as the element 2 but at a lower speed. a

In order further to aid in dispersion or mixing of the material under treatment and in order to overcome any tendency for the floating low speed mixing elementto rotate in unison with or at substantially the same speed as the high speed mixing element, the low speed mixing element is provided with agitator members which are suitably formed to stir the material or to direct is either inward toward the center or outward toward the walls of the vessel. or they may be arranged to scrape material from the walls or bottom of the vessel or to perform other functions. The agitator members. illustrated are in-the form of cylindrical beater rods 24 which extend upward from the member l8 to mix or stir the material and retard the rotation of the low speed mixing element.

Thus the surface 22 of the slow moving member I8 cooperates with the surface 14 of the rapidly rotating element 2 to cause material passing between the same to be dispersed, emulsified, ground or agitated to produce the desired result.

The agitating members also serve to break up any eddy currents which might tend to catch up light particles or other material and cause them to circulate in a path adjacent the walls of the vessel or elsewhere out of the current of material passing to the high speed mixing element. Such agitation further opposes the formation of a vortex about the shaft 4 so that while. agitating the material they prevent the passage of air intothespace between thesurfaces l4 and 22 ang l insure the maintenance of a film of material between these surfaces atall times during operation.

The upper ends of beater rods 24 are connected to a cross bar 26. which has a central cage 28 surrounding the, anti-friction bearing l2 on the shaft 4. The cage,28,is axially movrelative to the bearing I2 so that the whole low speed mixing element may move longitudinally of the shaft 4 to provide the desired sired to permit contact thereof or floating characteristics for said element and to permit separation of the member [8 from the element 2 in the event a lump of material or foreign matter attempts to pass between the surfaces 14 and 22 of the mixing elements.

If the cage 28 and the low speed mixing element are permitted to descend until the surface 22 of the member [8 engage the surface 14 of the element 2 there will be a direct frictional drive between the elements until the low speed mixing element is raised by material forced between the surfaces I4 and 22 by the impeller blades l6 and centrifugal force. However, generally it is preferred to maintain a predetermined initial or minimum clearance between the surfaces l4 and 22 and therefore an adjusting nut 30 is applied to the shaft 4 adjacent the lower surface 32 of the cage 28. By adjustment of the nut 30 it is then possible to vary the clearance between the surfaces [4 and 22 as del to maintain a minimum space therebetween. In some instances also it is desirable to urge the floating low speed mixing element down toward the high speed element 2 or to limit upward movement thereof and therefor a spring 34 is positioned to bear against the upper surface 36 of the cage 28 to force it downw ar d. The upper end of the for cleaning or to permitthe material to be subjected to other operations in the same vessel. Moveover, the'vess'el used need have no lower bearing member for supporting or centering the the mixing elements so that the device may be inserted directly into 'a'conventional drum or container in which the material is received or shipped.

In using the apparatus described for producing a typical dye containing emulsion the high speed mixing element is formed with the surface 14 thereof inclined at an angle of about 60 and prefrably's'mootli, rather than serrated as it is when used primarily for' grinding purposes. The inner surface 22 of the member 18 is similarly inclined sons 'to be substantially parallel with the surface 14 or only s'lightlymoreinclined so that the passage between these surfaces is' only slightly" tapered toward the periphery of element 2. 'The beater members'are in the form of smooth cylindrical rods as shown. The motor 6 is designed to drive the element 2 at a speed of 3600 R. P. M. and the adjusting nut 39 is positioned to'm'aintain an initial and minimum clearance of about .010 inch more or less between the surfaces and 22 of the mixingeleme'nts Th'e device is lowered into'a vessel containing the emulsion producing materials and dye and allowed to continue in operation until the desired emulsification and dispersion of the materials and dye has been produced. During initial stages ofoperation the materials undergoing treatment are relatively fluid and the clearance between the mixing elements is but little if any more than that established by the adjusting nut 30. Under these conditions the materials passing between the surfaces l4 and 22 and actuated by the element 2 serve to cause the low speed mixing element to rotate at approximately R. P. M.

5,2503% At thesame time the dye is dispersed and disintegrated'by the surfaces l4 and 22 so as to reduce any lumps or agglomerations of the dye that may be present.

As the operation continues and emulsification is effected the consistency of the material is altered and it becomes thicker causing the low speed mixing element ill to rise reducing the force with which the material tends to drag the element l about and increasing the force-required to move the agitating members or beater rods 24 through the material. The low speed mixing element thus automatically decreases in speed until it is rotating only relatively slowly.

In other uses of the device, as when dissolving or dispersing solids such as adhesives in liquids, the initial speed of rotation of the low speed mixing element may be relatively slow due to the fluid nature of the mixture but may increase considerably as the consistency of the material changes and its adhesion characteristics increase. An increase in speed of rotation of the low speed mixing element may also occur as the separation of the cooperating surfaces of the mixing elements decreases on dispersion of solids in a liquid medium. Thus in each application of the device the operation adapts itself automatically to the particular conditions to which it is subjected by reason of the floating character and impositive drive of the low speed mixing element. Furthermore, in each application of the device the material undergoing treatment cooperates with the adjacent surfaces of the mixing elements to function as a lower bearing for these elements, keeping them properly centered, so that only a single upper bearing is required to maintain the mixing elements in the proper relation during operation. From the foregoing description it will be apparent that devices embodying my invention are adapted for use in the treatment of a Wide variety of materials and in performing various operations. It will also be evident that numerous changes may be made in the form and arrangement of the elements of the device to render it particularly applicable to any special operation. Such alterations are contemplated and comprised within the scope of my invention and therefore it should be understood that the particular form of my invention shown in the drawing and herein described is intended to be illustrative of my invention and is not intended to limit the scope thereof.

I claim:

1. A mixing device comprising driving means, a shaft driven by said means, a mixing element fixed to said shaft and rotatable therewith, a bearing on said shaft and a second mixing element engaging said bearing and freely rotatable about said shaft, said second mixing element having a portion thereof located adjacent said first element in position to be driven impositively thereby through the action of material undergoing treatment and passing between said elements.

2. A mixing device comprising a container for the material to be mixed, two independently rotatable elements located in said container, driving means positively connected to one of said elements, means carried by the second element located adjacent the first for impositively driving the second element through material undergoing treatment and passing between said elements and means carried by said second element and projecting from. the second element into contact with other material in said container to insure relativerotation of said. elements duringa' ing operation;

V 3. A mixingdevicecomprising a shaft; an elejment driven by said shaft, a bearing on said shaft,

a second element'engaging said bearing and rotatable about said shaft, said second element being longitudinally movable with respect to said shaft and cooperating surfaces on said elements "for driving the second element through the action of material undergoing treatment and passing between said surfaces. l V 4. Amixing device comprising a shaft, a positively driven mixing element connected to said shaft; a floating mixing element rotatable about said shaft and axially movable with respect thereto, spaced parallel surfaces on said elements positioned to cooperate with material passing between the same during operation to center said floating mixing elements with respect to said positively driven mixing element and a slidable and rotatable bearing between said floating mixing element and said shaft and spaced axially from said positively driven'mixing element.

5. A mixing device comprising a shaft, a positively driven mixing element connected to said shaft near the lower end thereof, a floating mixing element rotatable about said shaft above the positively driven .element and movable axially of said shaft and means for supporting and centering said floating element with respect to the positively driven element including spaced parallel surfaces on said elements, means for passing material undergoing treatment between said surfaces during operation and a slidable and rotatable bearing between said shaft and the floating mixing element and located above and spaced an outwardly and downwardly inclined surface, driven mixing ele located adjacent the positively ment and cooperating therewith to cause material undergoing treatment and actuated by the positively driven mixing element to raise the floating mixing element so that it is supported and rotated by said material.

7. A mixing device comprisin a shaft, a positively driven mixing element secured to said shaft, a floating mixing element rotatable about said shaft above the positively driven element and axially movable relative to said shaft, said floating mixing element embodying a member having a central opening through Which said shaft extends and through which material passes to the positively driven mixing element and also having an outwardly and downwardly inclined surface located adjacent the positively driven mixing element and cooperating therewith to cause material undergoing treatment and actuated by the positively driven mixing element to raise the floating mixing elementrso that it is supported and rotated by said material and a sliding and rotatable bearing between the floating mixing element and shaft located above and spaced from the positively driven mixing element.

8. A mixing device comprising a shaft, a positively driven mixing element secured to said shaft, a floating mixing element rotatable about said shaft above the positively driven element and axially movable relative to said shaft, said floating mixing element embodying a member having a central'opening through which said shaft extends and through which material passes to the positively driven mixing element and also having an outwardly and downwardly inclined surface located adjacent the positively driven mixing element and cooperating therewith to cause material undergoing treatment and actuated by the positively driven mixing element to raise'the floating mixing element so that it is supported and rotated by said material; agitators connected to said member and projecting above the same, means connecting said agitators above said member and and shaft.

extending transversely of said shaft and a Slideable" and rotatable bearing between said means 9. Amixing device having a high speed mixing element and a floating mixing elementprovided with cooperating outwardly and'dow'nwar dly'in- SAMUEL K. NESTER.

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