USRE23772E

USRE23772E - Foaming apparatus

Info

Publication number: USRE23772E
Authority: US
Publication date: 1954-01-12

Description

Jan. 12, 1954 G. A. SPENCER Re. 23,772

FoAMING APPARATUS 5 Sheets-Sheet l Original Filed Feb. 3, 1950 IN VEN TOR. c@

.Spaun l TTF/VEKS Jan. 12, 1954 G. A. 'SPENCER Re. 23,772

FOAMINGI APPARATUS Filed Feb'. s, 1950 3 Sheets-Sheet 2 iginal INVENTOR. )L

y Re. 23,772

Jan. l2, 1954 G, A. SPENCER FOAMING APPARATUS 5 Sheets-Sheet 5 Original Filed Feb. 5, 1950 IN VEN TOR. (uofd. Spenr BY gi/@fm A rra/mw lReissue-rl Jan. 12, 1954 zam FOALIING APPARATUS George A. Spencer, Akron, Ohio, assigner to The Firestone Tire Rubber Company, Akron,

Ohio, a corporation of Ohio original No. 2,581,918, dans January s, 1952, sc-

rial No. 142,275, February 3, 1950. Application for reissue January 6, 1953, Serial No. 329,942

Hatter enclosed in heavy brackets I', 1 appears in the original patent but forms no part of this reissue specification; matter printed in italics .indicates the additions made by reissue.

9 Claims.

lto improvements in An important ob'ject of the invention is to provide an apparatus in which a viscous material such as compounded rubber latex may be introduced to be vigorously beaten or mixed in the presence of a metered amount of air for the production of a foamed product of uniform texture.

Another object of the invention is to provide foaming equipment of high output capacity as compared to existing equipmentfand which in effect is self-cleaning to the extent that undesirable deposits, which necessitate frequent cleaning of existing equipment, are either eliminated or minimized in a manner so that the normal operation of the equipment is not affected thereby.

Another object is to provide improved foaming equipment particularly adapted for the metered introduction of the product to be foamed, the air with which it is to be foamed, and certain additives, the latter being introduced subsequent to the initial stages of foaming.

Still another object of the invention is to provide foaming equipment of rugged construction, manufacturable at relatively low cost as compared to existing equipment, and requiring minimum maintenance and cleaning during continuous use.

Another object of the invention is to provide foaming equipment which offers the above-outlined advantages over existing equipment, and does s0 while presenting a substantially lower internal back pressure than heretofore obtained by any known type of equipment of comparable output capacity and physical dimensions.

An important object of the invention resides in the provision of a high speed foaming unit of improved design and offering a uniform axial flow path to the passage of material therethrough while said material is being continuously mixed with air and other ingredients, to maintain a uniform pressure-area relationship throughout the entire foaming cycle for the purpose of obtaining an end product of uniform cell construe.-v

tion.

Another important object of the invention is to construct a high speed mixer, the mixing elements of which may easily be regrouped in a. manner to vary the axial spacing thereof for the purpose of readily adapting the mixer for use with liquid ingredients of widely varying vis-` 2 A cosity, or alternately, to vary, through wide limits, the output rate of the mixer.

Still other objects and advantages will become apparent to persons skilled in the art upon examination of the drawings, the specication, and the appended claims.

In the drawings, in which like parts are identified by the same reference numera throughout the various views.

Fig. 1 is an elevational view, partially sectionalized along the axis of the apparatus shown, and illustrating a mixing apparatus incorporating a preferred embodiment of the present invention;

Fig. 2 is a sectional view taken along line 2-2 of Fig. l;

Fiig. 3 is a sectional view along line 3-3 of Fig. 4 .is a section taken along line 4 4 of Fig. 1; and

Fig. 5 is a diametric section of the stator portion of the mixer, showing disposition of the fixed blades.

As best shown in Fig. l, the device may include a foundation or base I0, of suitable construction,

5 such as a. metal casting or stamping, journal assemblies Il and I2, supportedabove base It by suitable brackets il, I5 and I6, Il, respectively; a mixing unit generically designated 2li, a casting 2| serving as a closure member for unit 2li, and including a bracket portion 22 for the rigid support of the mixer unit 20, preferably in the horizontal position shown. Journal supporting brackets Il, I! and i6, I1 may be cast. en bloc with supporting base lli to constitute upright integral extensions thereof, or may be otherwise fixed to base I0, for example by being welded or bonded thereto. Bracket 2 may be of stainless metal in the event the mixer is to be employed for the foaming of latex which is normally compounded with corrosive ingredients, and includes a generally planate portion 23, suitably apertured as hereinafter described, leading into a base portion 24 clamped to the face of a recessed portion of base Ill, by clamping bolts 25.

A shaft 30. rotatably supported in journal assemblies Il and i2, extends through an aperture provided in closure member 2| and into the mix- Aing unit. A rotor assembly within mixer unit 20,

as shown in Fig.'1, is mounted on a reduced diameter portion il of shaft 3l) in ilxed relation thereto. The stator portion of unit 20 includes a cylindrical housing 3l radially flanged at 35 for mounting to an annular integral centering rib l! on casting 2|, by means ofclamping bolts M and ll. Housing Il provides support for a plurality of axially positioned stator elements 38. each of 3 which includes a base portion l1 and integral blade portions $8, of reduced thickness, and circumferentially disposed at regular intervals as shown in Figs. 4`and 5. The bases I1 ofv stator elements Jl are of an axial dimension to permit said elements, Vwhen assembled as shown, to be the marginal areas thereof. Nozzles Il through Il are disposed diagonally in respect to plate portion 1|, eachnozzle being provided with -I an inlet bore 1I leading into a reduced bore 1I maintained inv unitary clamped assembly between i annular shoulder Il of housing and the planate surface of bracket portion 2l, by means of clamping pressure appliedby clamping bolts Il and Il. A locking key I9, also shown in Fig. 4.

is axially disposed in suitable grooves to locli the base members 31 of the stator elements Il to housing 34 to prevent relative rotation therebetween. The unsupported end of housing Il is iny ternally threaded at 40 for the threaded reception of an outlet spout I2, preferably a casting. provided with circumferentially spaced integral lugs Il to facilitate assembly and removal of the outlet spout.

The rotor assembly within mixer unit 20, above mentioned as being mounted on reduced portion I2 of shaft It in ilxed relation thereto, includes a plurality of axially mounted rotor elements I8, similar to stator elements I6 to the extent that each rotor element li-is provided lwith an annular Vdisposed cylindrical extending through closure .plate 1I to terminate yat a position radially outwardly of a centrally aperture 'Il provided-forreception of shaft il and packing gland housing 1l. The relative position of the apertures denning the terminus of bores 15 isbest shown at 1I, Fig. 3. The disposition of the nozzle bores 'Il is such as -to terminate in registry with the annular chamber defined intermediate the base portions of stator assemblies 38 andJ rotor assemblies Il, in whichvboth the stator blades and rotor blades are disposed. to feed vthe material to be foamed directly against the first circumferential series of y' rotor blades, as shown at 1I, Fig. l.

For the purpose of preventing the v entering housing Il through nozzles Il through Il. from working through casting 2l between aperture 'It therein and shaft II, a conventional base portion Il and integrally extending circumferentially spaced blade portions I9 of substantially 'reduced thickness as compared to the base portion. During assembly of the unit 2|), the rotory elements I8 are concentrically received on a sleeve Il, provided at its outer end with a radially flanged portion BI defining an annular shoulder against which the rotor element first mounted abuts. Sleeve 50, with rotor elements mounted thereon, is then mounted as shown over the outer end of shaft portion I2. The base portions Il of rotor elements 46 are of a thickness to insure positive clamping of said elements in unitary assembly when sleeve B is securely clamped against annular shoulder l defined by' the reduced portion 32 of shaft III. Sleeve Il) and rotor elements 4i are maintained in clamped assembly. as above described. by a contoured cap member I2, provided with a head screw 56 for threaded engagement with a suitable bore provided in the end of shaft portion l2.

As shown in the broken view, Fig. 1, sleeve Il is sealing gland is provided. This gland comprises a non-metallic sealing ring l! anda retaining ring 'II flanged at 81 to permit clamped engager ment of plural clamping bolts ll threadedly engaged in casting 2| and provided with nuts Il.

Since it may be desirable to introduce additives to the material after either partial or complete foaming has been eected. housing I4 may be provided with one or more hypodermic type linjection needles,` such as needle I2 extending from the exterior to the interior of housing 3l. A convenient method of introducing such a needle is through the provision of a rubber plug Il, confined under compression within a suitable housing aperture. For'example it may be desirable to introduce a gelling agent at a given point along the axial length of housing Il at a position such interiorly provided with a splined section Il for l registry with a mating spline section Il, provided exteriorly of shaft portion 32 throughout and end portion thereof. to constrain sleeve against relative rotation in respect to shaft 3l. The base of cap element l2 vis ofa diameter for registry with 'the flanged portion Il of sleeve il -to provide a smoothly contoured diverging exit channel SII for the foamed product as it leavesthe blade assembly portion of the device to enter a connecting collar 8|. An axially extending key l2, shown in Fig. 4, prevents relative rotation between the rotor blade assembly and sleeve Bl.

As best shown in Fig.`2, a plurality of inlet nozzleaare preferably provided Afor the purpose of equalizing the rate of material introduction to the device. While four such nozzles Il, il, l1, .and Il are shown in 90 .angularity. it is underf into a semi-circular closure plate portion 1I of reduced thickness, the central portion of closure .plate 'Il being of thicker section, as at 1I, than as shown, wherein the gelling agent is introduced into the foam in a manner to be thoroughly mixed therewith during the passage of the foam during travel thereof through the remainder of the mixer and prior to exit through the annular channel Il.

The construction of channel assemblies II and I2 may bein any conventional manner. Assemp bly I2 as shown may include an annular housing. II, which may be integralwith upright brackets I i and I1. A suitable ball bearing assembly .I

is disposed within housing II and constrained against axial disp1acement by a closure plate Il, clamped to housing Il by-plural stud bolts ll. In a like manner, journal assembly II may include a housing sl, integral with upright brackets .I4 and Il and adapted to receive a ball bearing assembly IDU which may be of the type adapted to receive axial thrust of shaft Il. This type of conventional bearing requires that shaft ll be provided with a radially extending rib Il! and with an end collar I Il retainedby nut Ill which threadedly engages a reduced and threaded Y extension I II1 of shaft Il. Inner race III of ball bearing assembly III ,is maintained clampedbetween annular rib I'l2 and collar Ill to rotate with shaft 20, while the outer race of ball bearing assembly |00 is maintained clamped between an annular shoulderl I2 oi'housing I and the inner walls III of a housing-like cap assembly III', clamped to housing Il by a plurality 'of-stud bolts 1. Suitable oil-retaining seals |2l, and

|2I, |22 are provided in Journal assemblies and closure )l in a manner not shown. Power may heap'- plied to pulley III through plural v-beltsJll which maybe driven directly from a shaft pulley or through conventional reduction machanism is merely illustrative, since it may he desired to-drive shaft 3l by direct coupling' to the shmi'tof a motor which maintains a proper ilxed speed, or in any other conventional manner.

The advantages of the above described mixing apparatus are numerous', but outstanding among =these advantages are the reduction oi.' overall dimensions as compared to existing equipment and freedom 'from the necessity oi' frequent cleaning during use. Heretotore mixers adapted for the roaming of such material as. latex and.. working vvon the principle oi'` ilxed and rotary lianes. have .beenof the so-called radia T type. wherein the material to be i'oamed is introduced at'ajpositionrsdislly inwardly .ofV theblades, t be centrli'ugally thrown 'outwardly prio'r to passage through the blade structure.

which is large in comparison to the volume of the eective annular mixing path. It is therefore not IOible to maintain a uniform'A pressurevolume relationship within the device, since the work material is subjected to a higher pressure while'actually passing through the eiective mixing path than 'it is subjected to leither .prior-to or 'subsequent to `leaving thatJpath but prior to exit from the mixer. n is wen known uint-.vanaf tioiilin the pressure-volume relationship within the mxer results in a foam of poorer quality and texture than is obtainable when uniformity of the pressure-volume relationshipjis tained. 'I'he elimination, in the present mixer, of an inactive central chamber not only permits substantial reduction in the diameter of the device, but totally eliminates the highly undesirable condition of maintaining an inactive central chamber which has been proved highly detrimental to the production of quality foam.

In actual practice, va device designed to run at 4 speeds between 1150 and 1175 R. P. M. may include a mixerunit the housing of ywhich has an outside diameter oi no more than 'I or 8 inches. In such a device the `effective annular mixing chamber, defined between the base ot the rotor and stator blade assemblies, may have a mean diameter of, for example, 8 inches and a radial width o! l inch or less. While such a 'mixenv working on axial flow. ,is of greatly-reduced diameter as compared to theradial type of mixers heretofore employed, the volume output is as great or greater due-to the absence oi constricting oriiices which have limited the output of the types heretofore known. For example, a mixer of the dimensions indicated above and operating at the speeds mentioned has .a normal output in excess oi 1.000 pounds of foamed'latex per hour. The method oi' introduc- In t'thistypeoi mixer there isl of ynecessity an internal'volume Y asma . 6 ing. For example, a proximately inches in outside diameter, 6

inches in axial length, and requiring 'l1/' horsepower input for the foaming oi' latex at 350 R.. P. M; operating speed, has a constant output .capacity of800 pounds of foamedrubber per hour. Applicants mixer, operating at 1150 R. P.v M., maintains an internal pressure in the range -olfv ilve to. ten pounds per square inch, whereas the 20 inch 'W2 horsepower input mixer mentioned above operates in the range o! to 30 pounds internal pressure. A high internal pressure will of course promote expansion of the material at the outlet spout, due to pressure di!- ferential in respect to the atmosphere, resulting in larger-bubblesand a resulting coarser foam. Since smooth texture o! the end product is desirable, decrease in` bubble size is the ultimate vgoal oi'iany such mixer. at least when employed for the foaming oi.' latex.

As best shown in Fig. 5, the disposition oi' the stator blade assembles is such that the radial extending blades Il of each blade assembly are staggered circumferentially in respect to the blades or thev immediately adjacent assembly to restrict ire'e' ilow oi' the material between the several series .of blades. Thus the material enteringthe mixing chamber at 13 must not 'only' lpass'vthroughthe rapidly rotating stator blades,

with va. small am'ountpassing between the ends thereof and the stator housingfut must follow a tortuous path presented by the circumierentially overlapping disposition oi the stator blades. It is apparent, therefore, that while the .work material is not subjected to undesirable variations in chamber volume as it passes through the. mixer, 4which has resulted in blow-by 'in Ithe prior art devices mentioned, complete admixture oi the material with air introduced to which the stator blades are afiixed. By

proper disposition of the blades therein, a stator assembly, the blades oi.' which are disposed in a generallyV helical configuration, may be inserted and removed by a so-called threading operation inwhich the stator assembly is worked into the rotorA assembly by a rotary movement. I n this adaptation of lthe invention, the dimensional limitations oi the blades may be empirically determined, in' respect to the normal operating speed oi' -the device, to eliminate what 'would amount to a low resistance substantially open path, allowing transfer oi' material through the device without proper mixing. While the adaptation shown includes a plurality of both rotor and stator blade assemblies with an equal number of ing material to be roamed directly into the an .any known-type oi' comparable horsepower ratevenly spaced blades on each assembly along theaxis of thedevice, it may be found desirable, especially for the proper mixing of certain materials, to vary the blade size and the circumferential-spacing on each or some of the assemblies, as well as the axialV spacing therebetween. Thus a mixing device incorporating all-of the principles taught-herein might be of a design whereby known type of mixer ap- I i 7 i. the incoming material and the air metered therewith is'subjected1 to a modest mixing action during the iir'st stage of axial flow through'the desarro' vice, tobe subjected to'progressively increasing agitation during continued axial now therethrough, or converseLv` a; complete reversal of this suggested arrangement might, under other circumstances,bedesirable.

'It is ofv course understood that the improved mixer described has wide applicability, and that its use for the foaming of'latex, as wellas the precise mechanical details included tor purpose" 8 radially fof said shaft, a series of spaced rotor plates secured to said shaft and having fingers disposed .radially of said shaft and extending into y the spaces between pairs of said stator plates, at

yleast one charging opening communicating with the interior of said housing, a generally conical ot exempliiication are'not tobe construed as l im itations. y

Whatisclaimedis:

[1. An apparatus for continuous production of vroamed liquid-air mixtures, which comprises a l central shaft with a plurality of iournal supports,

an auxiliary support, through and beyond which said shaft extends, a housing secured to said auxiliary support, cantilever fashion, and in `surrounding reiation to the extension ot saldshai't and having an exit passage axially uned with said shaft, a series o! spaced stator plates interiorl'y oi' said housing having ngers arranged radially of said shaft, a series. of spaced, rotor plates secured to said shaft and having lingers disposed radiallyoi' said shaft and extending into the spaces between pairs oi' said stator plates, said auxiliary support having charging openings cominunicating with the interior oi' said hous- [2. In a device asin claim 1, a generally conical head on the termnus of the said extension oi said shaft, and the said exit e on said housing having a converging form, defining, with said head, an annular, converging passage, leading to a final, tubular t [3, In a device as in claim 2, a sleeve surrounding said shaft and keyed thereto and to said rotor plates, a flange on said sleeve holding said plates in assembled relation, and said head being a separate member, secured to said shai't, and overwhereby l head .ony the terminus 0f the said extension of vsaid shaft. and the said exit passage on said r housing having a converging form, defining, with said head, an annular converging passage leading to a final tubular passage 10. An'apparatus for continuous production of ifoamed liquid air mixtures which comprises a central shaft with four-nal support extending ,cantilever'fashiom a housing ysecured in surrounding relation to the extension of said shaft and having an exit passage axially aligned with said shaft, a series of spaced stator plates interviorly of said housing having fingers arranged radially of said shaft, al series of spaced rotor plates secured to said shaft and having fingers disposed radially of said shaft and extending into the spaces between pairs of said stator plates, at

least one charging opening lcommunicating with the interior of said housing. a generally conical head on the terminus of the said extension of said shaft, a sleeve surrounding -said shaft and keyed thereto and to said rotor plates, a flange on said sleeve holding said plates in assembled relation, and said head being a separate member secured to said shaft, and overlying said flange, l to holdvsaid sleeve in position on said shaft.A l

11. An apparatus for continuous production of foamed liquid air mixtures which comprises a central shaft with journal support Vextending lying said flange, whereby to hold said sleeve in position on said shaft] f [4. A device as in claim 3, said sleeve having a iiplixied connection with said shaft] [5. A device as in claim 4. said housing being demountable from said auxiliary support where-- by said head may be removed ior disassembly of said plates] [6. A device as in claim 1, said charging openings being arranged generally tangentially to a circle concentric with the axis of said shaft, and

communicating at their termini directly with the space occupied by said lingers] ['l. A device as in claim 1,*said charging open- I ings being arranged generally tangentially to a circle concentric with the axis o! said shaft, and communicating at their termini directLv with the spaceoccupiedbysaidiingersandarrangedamcentral shaft with journal support extending cantilever fashion, a housing secured in surrounding relation to the extension of said shaft and having an exit passage axially aligned with said shaft. a series of spaced stator plates intericrly of said housing having fingers arranged cantilever'fashion, a housing secured in surrounding relation to the extension of said shaft and having an exit passage axially aligned with said shaft, a series of spaced stator plates interiorly of ,said housing having fingers arrangai radially of said shaft, a series of spaced rotor plates secured to saidshaft an'd having fingers disposed vradially of said s haft and extending intothe spaces between pairs of said stator plates, at least one charging opening communicating with the interior of said housing, a generally conical head on the terminus of the said extension vof said shaft,. a sleeve surrounding said shaft and splined thereto and to said. rotorplates, a

flange on said sleeve holding said plates in assembled -relation, and said head being a separate member secured to said shaft, and overlying said flange, whereby to hold said sleeve in position on saidshaft.` o

12. An apparatus for continuous production of foamed liquid-air mixtures which comprises a central shaft with -fournal support extending cantilever fashion," a housing secured in surrounding relation to the extension of said shaft and having an exit passage axially aligned with said shaft, a series of spaced stator plates interiorly of said housing having fingers arranged radially of said shaft, a series of spaced rotor plates .securedto said shaft and having fingers disposed radially of said shaft and extending into the spaces between pairs ofV said stator plates, at least one charging opening communicating with the interior of said housing, a generally conical head on the terminus of the said extension of said shaft, said charging opening being arranged generally tangentially to a circle concentric with the axis of said shaft and communicating with the space occupied by said fingers.

v 13. An apparatus for continuous production of foamed liquid-air mixtures whichr comprises a central shaft with fournal support extending cantilever fashion, a housing secured in surrounding relation to the extension of said shaft and having an exit passage axially aligned "with said shaft, a series of spaced stator plates interiorly `of said housing having fingers arranged radially of said shaft, a series of spaced rotor plates secured to said shaft and having fingers disposed radially of said shaft and extending into the spaces between pairs of said stator plates, at least one charging opening communicating with the interior of said housing, a generally conical head on the terminus of the said extension of said shaft, said charging opening being arranged generally tangentially to a circle concentric with the axis of said shaft, and communicating directly with the space occupied by said'fingers and arranged angularly to a plane perpendicular to the axis of said shaft.

rounding relation to the extension of said shaft and having an exit passage axially aligned with said shaft, a series of spaced stator plates interiorly of said housing having fingers arranged radially of said shaft, a series of spaced rotor plates secured to said shaft and having fingers disposed radially of said shaft and extending into the spaces between pairs of said stator plates, at least one charging opening communicating with the interior of said housing, a generally conical head on the terminus of the said `extension of said shaft, the fingers of said stator platesbeing staggered in succession so as to present only partial overlap in the adjacent fingers of adiacent plates.

1.5. An apparatus for continuous production of foamed liquid-'air mixtures, which comprises a central shaft with a plurality of journal supports, an auxiliary support, through and beyond which said shaft extends cantilever fashion, a housing secured in surrounding relation to the extension of said shaft and having an exit passage axially aligned with said shaft, `a series of spaced stator plates interiorly of said housing having fingers arranged radially of said shaft, a series of spaced, rotor plates secured to said shaft and having fingers disposed radially of said shaft and extending into the spaces between pairs of said stator plates, said auxiliary support having charging openings communicating with the interior of said housing; said charging openings being arranged generally tangentially to a circle asma concentric with the axis of said shaft, and communicating directly with the space occupied by said fingers.

16. An apparatus for continuous production of foamed liquid-air mixtures, which comprises a central shaft with a plurality of journal supports, an auxiliary support, through and beyond which said shaft extends cantilever fashion, a housing secured in surrounding relation to the extension of said shaft and having an exit passage axially aligned with said shaft, a series of spaced stator plates interiorlg of said housing having fingers foamed liquid-air mixtures, which comprises a' central shaft with a plurality of fournal supports,

' an auxiliary support, through and beyond which said shaft extends cantilever fashion, a housing secured in surrounding relation to the extension of said shaft and having an exit passage axially aligned with said shaft, a series of spaced stator plates interiorly of said housing having fingers arranged radially of said shaft, a series of spaced,

rotor plates secured to' said shaft and having fingers disposed radially of said shaft and extending into the spaces between pairs of said stator plates, said auxiliary support having charging openings communicating with the interior of said housing; the fingers of said stator plates being staggered in succession so as to present only partial overlap in the adfacent fingers of adjacent plates.

GEORGE A. SPENCER.

References Cited in the le of this patent or the original .patent UNITED STATES PATENTS 1Number Name Date l 1,449,623 Pfouts Mar. 27, 1923 1,487,208 Cooke et al Mal. 18, 1924 2,169,338 Dim; Aug..15, 1939 v FOREIGN PATENTS Number Country Date 689,465 France x May 27, 1930