US 2507349 A
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y 1950 J. A. RICE MIXING AND AERATING MACHINE Filed Oct. 28, 1948 INVENTOR. JbHNA-RiOE BY Mg Patented May 9, 1950 PATENT OFFICE MIXING AND AERATING MACHINE John A. Rice, Berkeley, Calif., assignor to Richard B. Rice, Santa Monica, and John Bergum, Concord, Calif.
Application October 28, 1948, Serial No. 56,999
The present invention relates to improvements in a Mixing and aerating machine intended particularly for the production of cellular concrete, and its principal object is to provide a machine of the character described that is simple in con- 5 struction, effective in operation and may be constructed at relatively small expense so as to be available for use even for limited building operations.
More particularly my invention is intended for use in connection with a conventional type of rotary mixer in which a frusto-conical drum is rotated on an inclined axis.
The materials employed in my cellular mixture are cement and water, or cement, sand and water, to which mixture is added a special compound serving the purpose of incorporating air cells into the mixture to produce a light-weight, cellular concrete.
. In carrying out my invention it is necessary to incorporate a large amount of air into the mixture during the mixing process, and my machine is particularly intended to serve this purpose.
It is proposed for this purpose to provide a plurality of frusto-conical screens of progressively diminishing size in concentric relation with the drum, the screens being built up into a unitary structure and being made to revolve as such, either with a drum or with a central shaft revolvable in the drum.
The principal object of the screen assembly is to cause the material to climb with the ascending side of the screen structure and to drop from a certain elevation through the various screens upon the bottom of the drum, resembling a water i fall, whereby a large amount of air is entrained in the mixture and thoroughly distributed through the latter.
Further objects and advantages of my invention will appear as the specification proceeds, and the novel features of my invention will be fully defined in the claims attached hereto.
The preferred form of my invention is illustrated in the accompanying drawing, in which Figure 1 shows a side view of my mixing and aerating machine, with the drum disposed in vertical position,
- Figure 2, an axial vertical section through the drum in inclined or working position,
. Figure 3, an end view of my drum,
Figure 4, a sectional detail view taken along line 4-4 of Figure 2, and
Figure 5, a fragmentary inside view of a portion of the screen structure.
While I have shown only the preferred form of my invention, I wish to have it understood that various changes and modifications may be made within the scope of the claims attached hereto without departing from the spirit of the invention.
Referring to the drawing in detail, the drum I" of my invention may be of conventional form and is here shown as being frusto-conical, its smaller end being open and its larger end being closed by means of a spherical cap 2 so as to form a material-retaining pocket when the drum is positioned with its axis horizontally. The cap has an external flange 3, the lower face of which is toothed to form a gear 4 adapted for operation by a pinion 5 to impart rotary motion to the drum. The. inner face of the cap is concave to increase the material-retaining capacity of the drum pocket.
The drum is supported by means of an axial shaft 6 projecting outwardly from the cap and being revolvable in the hub 1 of a yoke 8 having two opposing journals 9 revolvable in bearings l0 mounted on suitable standards I I. The pinion 4 is mounted on a shaft H which latter is revolvable in one of the journals 9 and is operated by a pulley l 3 suitably connected to a driving motor.
Figure 1 shows the drum in vertical position, but the drum may be swung in one direction into the tilted position shown in Figure 2, which is the working position and tends to increase the material-retaining capacity of the drum pocket and may be swung into the other direction into reversed position for discharging a load. For turning the drum I provide a handle M, a suitable stop (not shown) being provided to limit the swinging movement in one direction to working position.
On the inside of the drum I provide a plurality of frusto-conical screens l5 of progressively diminishing size, the screens being mounted c0- axially with the drum and shaped to parallel the drum wall, as shown.
In the form illustrated the screens are shown as beingfixed to the drum to rotate therewith, but the screens would perform the same function if fixed with respect to a central shaft and made revolvable in a non-rotating drum.
The screens may be made of any suitable material but are preferably made of expanded metal, about inch mesh, with-the longer axes of 3 in about the same proportion, with the screens occupying substantially one-third of the diameter of the drum at its base.
The screens are preferably spaced about 1 inch apart. If spaced more closely the material is apt to lump and to interfere with the process, and if they are spaced further apart, the machine would lose in. efficiency and more time would be required for a given mix.
The screens extend rearwardly to the rear wall of the drum, but at the front end they are prei-' erably progressively foreshortened, as, shown, so that, when the drum is in a tilted working position, all the lower screen edges lie, in the horizontal plane of the lower edge-of thefront end of the drum.
Each screen may be made. as a complete continuous unit, but for ease of manufacture and convenience of assembly, I preferably make each screen in four separate sections, which may be slightlyspaced. from one another peripherally, asat, it, The different sections are anchored to the-wall of the drumby means of bolts i1 passing through; the spaces between the sections, with spacing sleeves l8 interposed between the secnonsof adjacent; screens, and washers i9 interposedibetween the sleeves so as to bear on opposite sides, of thescreen sections. Thus the tightening, of nuts 20, onthe inner ends of the bolts clamp all, the screen sections to the wall of the drum in properly'spaced relation.
In operation, with thedrum. in upright or in inclined. Working; position, the material comprising cement, water and, compound, or cement,
sand, water and. compound, is" placed into the drumfin; properproportions, the drum being filled to a level somewhat below the lower front edge oi the drum whenthe latter is tilted.
The drumis, then rotated for mixing the materials. Duringthe rotationv the screen assembly 1 raises the material along; the ascending side of the drum to; a point approaching the top center and the-raised material drops through the different screens, upon the, lower portion of the drum, somewhat resembling a water fall, which causes-a large amount of, air to be rapidly entrained, iii-the mixtureland-i to be thoroughly distributedthrough the same; A three-minute run usually suificient to finish the product which may thenbe-readily removedby gravity when the drum is tilted in. the opposite direction.
1;. In a mixing. and aerating, machine for producing cellular concrete, a drum closed at one endand open at its other end, and a screen assembly mounted therein concentrically with the drum, the screenassembly comprising a plurality of: screens arrangedinspaced relation to the wall ofthedrum and to each other, with the inner edgesofthe screenscontacting the closed end of the drum and the outer edges progressively recedingfromthe outer-endof the drum.
2. In, a. mixing and aerating; machine for pro-- ducing cellular; concrete. a; drum closed at one end and openat. itsother end, means for tiltingly supporting the drum with.- freedom of rotation on an inclined axis, a screen assembly within the drum and comprising a plurality ofspaced screens, the outer edges oithescreens being proressively foreshortened to bring the lowest points of. said edgesinto the horizontal planeof the corresponding point at. the open end of thedrum.
3. A mixing and aerating machine for producing cellular cement, comprising a frusto-conical drum closed at its larger end and open at its smaller end so as to form a material-retaining pocket when the drum is supported with its axis in horizontal position, and a irusto-conical screen assembly mounted therein concentrically with the drum, the screen assembly comprising a plurality of frusto-conical screens arranged in spaced relation to the wall of the drum and to each other and extending to the rear wall of the drum so as to cause comminuted material confined in the pocket to be carried upward by the ascending 1 portion of the screen assembly when the latter is .rotated and tube dropped from an elevated position uponthe lower portion of the screen assembly.
4. A mixing and aerating machine as defined in claim 3, in which the drum is supported on an inclined axis whereby the material-retaining capacity of' the pocket is; increased.
5;. A mixing and aerating machine as defined' in, claim 3,, in; which the closed end is. made-concave to increase the materal-retaining capacity of the drum pocket.
6. A; mixing and aerating, machine as defined" in claimB, inwhichthe; drum is supportedon anv inclinedv axis and in which theclosed endis madeconcave to increase the material-retaining ca-- pacity of, the drum pocket.
7.. A mixing; and, aerating machine as defined: in, claim, 3, in which the screens are made of expanded metal with the longer axes of the open-- ings arranged lengthwise ofthe drum.
8. Amixingand aerating machine for produc ing cellular cement, comprising a drum closed at its; rear end and having; a reduced throat at its, front end: to. define a, material-retaining pocketwhen the drum is supported with its axis in horizontal position, and a screen assembly mounted in the drum, the screen assembly comprising a plurality of screens arranged: in spaced relation to the wall of the drum andto each other and extending to the rear wall of the drum so as to cause comminuted. material confined in the pocket to becarried upward] by the ascending portion of the screen: assembly when the latter is rotated and to be dropped from, an; elevated position upon the lower portion of the screen assembly.
9. A mixing and aerating machine as defined in claim 8, in; which the drum is supported on an inclined axisand in. which the rear end is made concave to increase thematerial-retaining capacity of the drum pocket.
10-. A mixing and aerating machine as defined in claim 8, in which the screens are made of ex-- panded. metal with the longer axes of the openings arranged lengthwise of thedrum.
JOHN A. RICE.
EFERENCES CITED- The following references are of record in the file of this patent:
UNITED. smirns PATENTS 1,793,017 Runge Feb. 17', 1931