US 3222038 A
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Description (OCR text may contain errors)
1965 G. w. ASHCRAFT 3,222,038
MIXING MACHINE Filed Aug. 9, 1963 2 Sheets-Sheet 1 INVENTOR George W flshcmff United States Patent 3,222,038 MIXING MACHINE George W. Ashcraft, 5818 E. 12th St., Kansas City, Mo. Filed Aug. 9, 1963, Ser. No. 301,102 7 Claims. (Cl. 259-105) This invention relates to mixing machines for use in the mixing of paint, the comminution of grain, and in various other applications where it is desired to mix a plurality of substances or to reduce the particle size of a granulated product.
The ingredients of common paints include resins, pigments, solvents, and a vehicle or base. These constituents must be mixed together to form the finished product. Such mixing involves considerably more than mere agitation of the various ingredients since the paint pigment usually must be dispersed in order to form a homogeneous solution or suspension. This is because the pigment is composed of minute particles which tend to form small agglomerates. Mixing breaks up the agglomerates and disperses the particles throughout the solution.
Heretofore, ball mills have been employed to effect the desired mixing of these ingredients to form the finished paint. Although ball mills have proven satisfactory in mixing the various paint constituents to form a homogeneous solution or suspension, such mills often require several days of operation before the ingredients therein become mixed to desired standards. Thus, the ball mill is relatively slow as compared with mixing apparatus in common usage in other fields.
Another type of mixing device employed heretofore in the mixing of paints uses an agitator to speed the formation of a homogeneous solution or suspension. Such agitator-type mixers, however, are unfit for paints where dispersion of the pigment particles must be achieved in order to form the finished product.
It is, therefore, the primary object of this invention to provide mixing apparatus for use in the paint industry that will mix paint ingredients to the desired standards in a shorter period of time than a ball mill and will also effect dispersion of pigment or other particles.
It is another object of this invention to provide mixing and dispersing apparatus that impresses shear forces upon the products being mixed in order to achieve mixing and dispersing thereof.
It is a further object of this invention to provide mixing apparatus as aforesaid having improved circulation of the products to be mixed to increase the speed of mixing thereof.
Besides the mixing of paint, the instant invention is also suitable and capable of effecting mixing and comminution of grains such as wheat, etc. Manifestly, the reduction of wheat and other grains to form flour and the like is undertaken on a wide scale. The instant in vention provides greater speed and efficiency in this operation than heretofore obtainable with relative simplicity of structure.
Therefore, it is an important object of this invention to provide apparatus for reducing the particle size of wheat and other grains in the formation of flour and the like.
Another important object of this invention is to provide mixing apparatus especially suitable for use with substances susceptible to shear forces for effecting reduction of particle size.
Still another object of this invention is to provide mixing apparatus wherein dispersion of agglomerated particles or comminution of granulated products is achieved without the use of engaging teeth or moving parts subject to high stresses.
Yet another object of this invention is to provide mix- 3,222,038 Patented Dec. 7. 1965 ice ing apparatus wherein the products to be mixed are heated by forces exerted thereon by the apparatus to thereby achieve improved mixing.
Further objects will become apparent as the detailed description proceeds.
In the drawings:
FIGURE 1 is a central, vertical sectional view of the apparatus with the interior parts thereof including the drive shafts and the adjustable spacing mechanism shown in elevation for clarity;
FIG. 2 is a sectional view taken along line 22 of FIG. 1 with certain components shown in elevation for clarity;
FIG. 3 is a plan view of the upper plate of the mixing apparatus;
FIG. 4 is a plan view of the middle or inner plate of the mixing apparatus;
FIG. 5 is a fragmentary view taken along line 55 of FIG. 1;
FIG. 6 is a fragmentary view taken along line 66 of FIG. 1;
FIG. 7 is a fragmentary, central, vertical sectional view of the lower plate of the mixing apparatus and its associated retainer showing the inner drive shaft in elevation;
FIG. 8 is a detailed view along line 88 of FIG. 4; and
FIG. 9 is a vertical, sectional view through the housing of the gear drive mechanism showing the mechanical components of the mechanism in elevation.
Referring to the figures, the numeral 10 denotes a receptacle or tank employed to receive the products to be mixed. Receptacle 10 has a top 12 with an inlet 14 therein. Inlet 14 receives a cap 16 and permits the loading of products into receptacle 10 upon removal of the cap. Disposed within receptacle 10 and adjacent top 12 is a product deflector 17, the function of which will be fully described hereinafter. Deflector 17 comprises an annular, outwardly convex surface formed by bending the sides of the receptacle inwardly to form a restriction 17'.
Receptacle 10 is provided with a bottom 18 having an outlet 20 therein permitting egress of products from the receptacle following the mixing operation. A pipe 22 communicates outlet 20 with a valve 24, opening of the valve permitting such egress when desired by the opera tor of the apparatus.
Top 12 serves as a mounting platform for a U-shaped bracket 26. Bracket 26 has a housing 28 of a gear drive mechanism 29 mounted thereon with tubular output shaft 30 of mechanism 29 extending through the bracket and into receptacle 10 through openings 31 in top 12. Mechanism 29 is operably coupled with a prime mover 32 for effecting rotation of shaft 30 in a manner to be fully described hereinafter. Prime mover 32 may be an electric motor.
An arm 34 is hingedly attached at 36 to one edge of top 12, the other end of the arm terminating in a fork '38. Fork 38 receives a pair of opposed pins 40 (as is evident in FIG. 6), the pins extending from and being rigid with a ring 42. Ring 42 is internally threaded to mate with the external threads of a screw 44.
Screw 44 is mounted on top 12 at 46, such mounting at 46 permitting both rotation of screw 44 and swinging movement thereof in a vertical plane through arm 64. The upper end of the screw is rigidly secured to a crank 48 permitting manual turning of the screw by the operator of the apparatus.
It may be seen, especially in FIGS. 1 and 5, that arm 34 is provided with an eye 50 which has disposed there- Within a bearing assembly 52. Bearing assembly 52 comprises an outer race 54 having opposed pins 56 extending therefrom and an inner race 58. Pins 56 are slidably received by corresponding slots 60 in eye 50. The inner race 58 of bearing assembly 52 surrounds and is rigid with shaft 30, thereby preventing longitudinal shifting of shaft 30 while arm 34 is stationary.
In FIGS. and 9 it may be seen that a shaft 62 is concentrically disposed within shaft 30 for rotation relative thereto. Bearings (not shown) spaced longitudinally of the shafts and disposed therebetween may be employed to permit shaft 62 to rotate freely within shaft 30 with a minimum of friction. A thrust bearing 63 in housing 28 suspends shaft 62 by its upper end.
A pinion 64 is rigid with the upper end of shaft 62. A pinion 66 is rigidly attached to the upper end of shaft 30, both of the pinions 64 and 66 being in engagement with a ring gear 68. Ring gear 68 is mounted on output shaft 69 of prime mover 32, it being evident that mechanism .29 thus comprises a ring gear and pinion assembly for effecting rotation of shafts 30 and 62 in opposed directions upon actuation of the prime mover.
A bushing 70 in housing 28 permits longitudinal shifting of shaft 30 and pinion 66 while both of the shafts are being driven by the prime mover. It will be appreciated when the operation of the apparatus is described hereinafter that such longitudinal shifting of shaft 30 is effected by operation of crank 48 which, in turn, swings arm 34 about hinge 36.
The mixing structure proper of the instant invention comprises three plates or discs 74, 76 and 78. Disc 74 is attached to shaft 30 by four curved legs 79 rigid with the lower end of the shaft. Disc 74 has a series of apertures 80 therethrough in equally spaced relationship to a central opening 82 in the disc communicating the opposed faces thereof. Rows of apertures 84 and 86 in progressively lesser spaced relationship from central opening 82 are also provided in disc 74.
Four radial, inclined vanes 88 are attached to the upper side of disc 74 and are canted toward the direction of rotation of the disc, such rotation being effected by prime mover 32 in a manner to be described hereinafter. Lower disc 78 is similar in construction to disc 74, the two discs being interconnected by four rods 90 which are rigid with and depend from corresponding legs 79. Each rod 90 extends through an associated hole 92 in disc 74 and is slidably received by a corresponding opening 93 in disc 78, a nut 95 being attached to the lower end of each rod to maintain disc 78 on the rods. A compression spring 94 surrounds each rod 90 and bears against the opposed sides of discs 74 and 78. The inner or middle disc 76 is held between discs 74 and 78 in equally spaced relationship thereto by eight leaf springs 96 mounted in corresponding recesses 98 in the upper and lower sides of disc 76. Four leaf springs 96 are mounted on each side of the disc as is clearly revealed in FIG. 4.
It may be seen that disc 76 has three continuous rows 100, 102 and 104 of apertures therethrough. The rows 100, 102 and 104 are in progressively lesser spaced relationship from a central, rectangular opening 106 in disc 76.
Reference is made particularly to FIGS. 2 and 7 for an understanding of the manner in which the discs 74, 76 and 78 are driven. Shaft 62 has a transversely circular section 108 and a transversely rectangular section 110, the section 110 extending through opening 82 in disc 74 and into mating engagement with opening 106 in disc 76. Section 110 also extends through a circular opening 112 in disc 78. The lower end of section 110 is provided with a retainer or pressure plate 116 rigid therewith and abutting the underside of disc 78. The mating surfaces of disc 78 and retainer 116 form bearing surfaces and permit relative movement of disc 78 and retainer 116 during operation of the mixing apparatus. Section 110, therefore, is in driving engagement with disc 76 only.
In the operation of the apparatus, products to be mixed are loaded into the receptacle 10 through inlet 14 and the inlet then closed by cap 16. Motor 32 is then energized, it being understood that the shafts 30 and 62 are rotated in opposite directions. Thus, discs 74 and 78 are rotated in one direction (counterclockwise looking vertically downwardly on the apparatus) while disc 76 is rotated in the other direction.
Since vanes 88 on the upper side of disc 74 are canted toward the direction of rotation of the disc, the products to be mixed are circulated downwardly through the rows of apertures 80, 84 and 86 and into the interior of the disc mechanism between disc 74 and disc 76. Mixing and dispersion or comminution then occur because of the shear forces impressed upon the products by the relative movement of discs 74 and 76. It may be appreciated that the rows 100, 102 and 104 of apertures in disc 76 permit further passage of the products downwardly through the disc mechanism and into the space between discs 76 and 78, whereupon additional mixing occurs between these latter two discs. Continued circulation of the products results in flow thereof downwardly through apertures (not shown) in disc 78, the four radial vanes 114 on the lower side'of disc '78 assisting in the establishment of a flow pattern from top to bottom through the disc mechanism. Deflector -17 serves to restrict the circulation to the vicinity of the disc mechanism and prevents excessive upward flow of the products away from the mechanism. It should be noted that, although shown and described as an integral part of receptacle 10, deflector 17 may comprise a sleeve that is inserted within the receptacle and adjustable toward and away from the mixing discs as desired.
Spacing between the discs is somewhat critical if the desired shear forces are to be produced within the disc mechanism. (The outer discs are shown in the drawings spaced from one another the maximum distance, i.e. disc 78 resting on nuts 95.) For this reason, arm 34 and its associated structure are provided to permit adjustment of the spacing between the discs. Rotation of crank 48 moves arm 34 toward and away from top 12 and effects reciprocal movement of shaft 30. When shaft 30 is moved downwardly, the legs 79 extending from shaft 30 force disc 74 downwardly toward disc 78 against the action of springs 94 and 96 since disc 78 is maintained against downward movement by retainer 116. Conversetly, upward movement of shaft 30 permits discs 74 and 78 to move away from one another under the action of springs 94 and 96.
Attention is directed to the fact that, regardless of the distance between discs 74 and 78, disc 76 will always remain in equally spaced relationship from the two outer discs. This is because of the action of leaf springs 96 which serve to suspend or float disc 76 between discs 74 and 78.
It should be understood that the coil springs 94 may be omitted from the adjusting mechanism and leaf springs 96 employed alone to effect the adjusting function. Furthermore, the leaf springs 96 may be omitted and the coil springs 94 and associated rods replaced by spacer bars if no adjustment of the disc spacing is desired. The adjustable feature may not be needed in certain grain comminuting applications. The spacing adjustment between the discs is important in most applications, however, since the magnitude of the shear forces impressed upon the products being mixed is dependent upon this spacing. The closer the spacing, the greater the shear and hence, the greater the heat developed in the products being mixed. Therefore, the spacing should be adjusted to permit maximum force on the products without overheating.
The spacing of the discs is especially important when substances such as the constituents of paint are being mixed in the apparatus. Some degree of heat is needed if the paint pigment is to be deglomerated and properly mixed with the remainder of the ingredients, yet overheating must be avoided to prevent product damage. In this regard, receptacle may be surrounded by a water jacket or other suitable means for preventing overheating.
It has been found that optimum results are obtained when the apertures in the discs comprise approximately 50% of the surface area thereof. It should be understood that these apertures assist in the generation of the shear forces, but with a sacrifice in circulation the apparatus is operable with the disc apertures extending only partially through the discs.
Although three discs are shown herein, additional discs may be added to or subtracted from the disc mechanism shown, depending on the characteristics of the substances being mixed and the efiiciency and speed of operation desired. Furthermore, one disc or set of discs may be maintained stationary, while the other disc or set thereof is rotated, and it is not requisite to the operability of this invention that the nonrotated disc or discs be provided with apertures therein.
Having thus described the invention, What is claimed as new and desired to be secured by Letters Patent is:
1. Apparatus for mixing products comprising:
a receptacle for receiving said products;
an inner disc and a pair of outer discs in parallel, co-
axial relationship with one another, each of the discs having a plurality of apertures therethrough communicating opposed sides thereof; means mounting the discs in the receptacle for rotation of the outer discs as a unit in one direction about said axis and for rotation of said inner disc in the other direction about said axis with the discs disposed in sufliciently closely spaced relationship to one another to cause shear forces to be impressed upon said products when the discs are rotated; and
means operably coupled with said discs for driving the latter in said directions, whereby to produce said shear forces.
2. The invention of claim 1, wherein said inner disc is equally spaced from said outer discs.
3. The invention of claim 1, wherein said axis is substantially vertical, there being a product deflector in the receptacle above said discs.
4. The invention of claim 1, wherein said axis is substantially vertical, there being a plurality of radial vanes 5. The invention of claim 1, wherein is provided a plurality of inclined, radial vanes on the side of one of said outer discs remote from the inner dics, said vanes being canted toward the direction of rotation of said one outer disc.
6. The invention of claim 1, wherein said apertures in each of the discs reduce the surface area thereof approximately one-half.
7. Apparatus for mixing products comprising: a receptacle for receiving said products; an inner disc and a pair of outer discs in parallel, co-
axial, equally spaced relationship with one another, each of the discs having a plurality of apertures therethrough communicating opposed sides thereof;
yieldable means on the opposed sides of said inner disc in engagement with the proximal sides of said outer discs for maintaining said equal spacing regardless of the distance between said outer discs;
structure mounting the discs in the receptacle for rotation of the outer discs in one direction about said axis and for rotation of the inner disc in the opposite direction about said axis, said structure including a reciprocable member operably coupled with one of the outer discs for moving the latter toward the other outer disc against the action of said yieldable means and away from said other outer disc under the action of the yieldable means, whereby to vary said distance between the outer discs to change the magnitude of the shear forces impressed upon the products when the discs are rotated and means interconnecting said outer discs for relative movement thereof along said axis and for rotation as a unit about said axis; and
means operably coupled with said structure for driving the discs in said directions, whereby to produce said shear forces.
References Cited by the Examiner UNITED STATES PATENTS 897,481 9/1908 Pease 259-24 1,655,447 1/1928 Wait 259-435 2,301,204 11/1942 Fields. 2,626,135 1/1953 Serner 259134 X 2,734,728 2/1956 Meyers 24l161 X CHARLES A. WILLMUTH, Primary Examiner.