CA1212214A - Modular mixing apparatus including interchangeable fluid processing means - Google Patents

Abstract

TITLE

MODULAR MIXING APPARATUS INCLUDING INTERCHANGEABLE FLUID
PROCESSING MEANS

ABSTRACT

A helically moving fluid body leaving an extruder screw and brought into contact with rotating shearing means, undergoes laminar displacement, is then guided through a stationary sleeve along undulating linear paths of travel of relatively short axial length, and thereafter undergoes further laminar displacement and discharges into a die.
During movement of the fluid mixture along the undulating linear paths of travel subdivision and blending of substantially all of the material in the fluid body, which is not in a fluid state, takes place. Thereupon the blended mixture is advanced to a die member at a desired fluidity and temperature in response to die requirements. Heating of the barrel is significantly reduced and energy conser-vation of an appreciable nature is achieved.
In carrying out mixing as noted above there is em-ployed a modular mixing apparatus constructed with multiple processing means suitable for shearing, kneading, flow diverting, dispersing, blending and the like. The multiple processing means includes a basic component assembly with which other components may be employed interchangeably to deal with varying types of fluid or plastic bodies wherein solid material may be present.

Description

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lo 214 FIELD OF THE INVENTION

Mixing a fluid or plastic mass with modifying agents, additives and the like to produce a homogeneous material is customarily attempted by mixing apparatus which is well known in the art and occurs in various forms.
Conventional extrude screw and barrel apparatus is employed either separately or in conjunction with static flow dip venting means. These conventional mixers and extrudes are all shear dependent in that flow of plastic material may be-come channelized with hotter, less viscous material tending to run in channels along the central axis of the extrude section and cooler, more viscous material tending to adhere to extrude barrel portions at some points.
For example, with a conventional extrude screw having 24 turns, only 80% of the material may be melted by the first 12 turns, and the remaining 12 turns may produce only a 95% melt. Periodically the more viscous or unmelted material may become torn away from the barrel and swept into the die in which forming is to take place.
To prevent this, more heating and pressure is often exerted through the extrude screw with excessive use of energy and undesirable increase in temperature of material in the barrel which can degrade some portions of the material. Thus the need exists for more complete melting and mixing which can be carried at localized points to deal with these Defoe-gullies and prevent lack of homogeneity in the molded product.

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SUMMARY OF THE INVENTION

The present invention relates to an improved modular mixing apparatus and to improved methods of processing a fluid or plastic mixture wherein inter-changeable processing modes are employed.
It is a chief object of the invention to provide improved methods and means for mixing fluid or plastic bodies.
Another object of the invention is to devise a modular mixing apparatus which combines a plurality of no-toting shear ring means with a stationary sleeve element by means of which luminary displacement of a fluid material is achieved, then dispersed material is separated into spaced apart streams of material, and the spaced apart streams are . further subdivided.
Still another object of the invention is to combine in a single rotating body a plurality of processing modes which may be selectively employed in in interchangeable relationship to one another to process fluid or plastic bodies of varying characteristics.
Another object is to provide means for retrofitting an extrude screw where an appreciable percentage of rota-lively viscous or unmelted characteristics resists mixing and blending and requires intensive extrude processing.
It has been determined that the foregoing objectives may be realized by luminary displacement of a fluid mass which is thereafter guided along undulating linear paths of travel of relatively short axial length, which material thereafter undergoes further luminary displacement.

The combined effect of luminary displacement of fluid material followed by traveling the displaced ma-tonal along undulating linear paths of short axial length and to undergo further luminary displacement, operates to achieve a high degree of intimate mixing and blending by which substantially all material in the fluid mass which is not in a fluid state is converted into a part of a homogeneous product.

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BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an elevation Al view illustrating a basic component assembly of one desirable form of modular extrude apparatus of the invention combined with an ox-truer barrel which is shown fragmentarily.
Figure 2 is a diagrammatic view of conventional plastic processing apparatus including an extrude screw, an extrude barrel and portions of a dye shown in cross section with which a modular mixing apparatus of the in-mention is combined.
Figure 3 is a cross section taken on the line 3-3 of Figure 2.
Figure 4 is an exploded view showing in further detail the component parts of the modular extrude apparatus shown in Figures 2 and 3.
Figure 5 is a cross section taken on the line 5-5 of Figure 3.
Figure 6 is a cross section taken on the e 6-6 of Figure 3.
Figure 7 is a cross section taken on the line 7-7 of Figure 3.
Figure 8 is a cross section taken on the line 8-8 of Figure 3.
Figure 9 is a cross section taken on the line 9-9 of Figure 3.
Figure 10 is an end elevation Al view showing a dispersing tip element in the modular mixing apparatus.
Figure 11 is a fragmentary perspective view showing the component parts of the mixing apparatus of Figures 2 and 3 and indicating portions of a barrel member having been broken away to indicate by arrows a changing flow of material along undulating paths of travel of short axial length.

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Figure 12 is a fragmentary cross-sectional view showing portions of the mixing apparatus and indicating rotational direction of the various modules.
Figure 13 is a cross sectional view taken on the line 13-13 of Figure 12 illustrating diagrammatically one path of flow of fluid material.
Figure 14 is another view taken on the line 14-14 of Figure 12 Figures 15, 16, 17, 18, 19 and 20 are additional views similar to Figure 13 but taken on respective cross sectional lines 15-15, 16-16, 17-17, 18-18, 19-19 and 20-20.
Figure 21 is a fragmentary cross sectional view of a modified form of mixing apparatus of the invention and particularly showing the combination of kneading block apparatus combined with the rotating screw driver shaft.
Figure 22 is a fragmentary cross sectional view of a barrel member showing mixing apparatus of the no mention corresponding to the assembly shown in Figure 21.
Figure 23 is a cross section taken on the line 23-23 of Figure 22.

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DETAILED DESCRIPTION OF THE INVENTION
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In general the modular mixing apparatus of the invention includes: (1) a main shaft which is en-gaged with a threaded end of an extrude screw and no-taxable therewith, (2) spaced apart shear ring elements notable with the shaft, and (3) a stationary shearing control sleeve which is located between the shear ring elements, disposed around the driver shaft, and fixed to an outer ox-truer barrel component of the apparatus.
This basic component assembly is made use of to carry out multi-stage mixing in a rapid and unique manner.
A helically moving fluid body in an extrude screw and barrel apparatus is brought into contact with rotating shear ring means to undergo luminary displacement; it is then guided through a stationary shearing control sleeve along undulating linear paths of travel of relatively short axial length; and thereafter undergoes further luminary displacement by shear ring means.
Referring in more detail to the Figures shown in the drawings, Figure 1 illustrates the modular mixing apparatus of the invention in one basic form. Figures 2-23 illustrate other modular mixing apparatus having various processing means combined in one form or another with a basic component assembly of parts 1, 2, 3, and lay ~2~L2~1~

The apparatus of Figure 2 may, for example, be supported on a bed plate P and movie include a feed section having a hopper H into which plastic material is furnished in the usual manner to an extrude screw S received within a barrel B and power driven through a reduction gearing R
by a motor M. T denotes thermal control means in commune-cation with the extrude barrel B.
It is customary to construct extrude screws such as the screw S with a predetermined length to diameter ratio. As shown in Figure 2 diagrammatically, screw S may have a length which is twenty times the diameter of the screw S including a feed section of five diameters, a transition section of seven diameters, a metering section of six diameters and a mixing section of two diameters.
In this mixing section of two diameters is lo-acted the modular mixing apparatus of the invention and it should be understood that this modular mixing apparatus as hereinafter described in detail may be combined with an extrude screw having a length of 18 diameters or other lengths as an original construction. However, where it is desired to modify a screw having some given length such as a length of 20 diameters, or some other number of die-meters, the screw may be cut to a length of 18 diameters, for example, and then retrofitted with the modular mixing apparatus of the invention by internally threading the cult off end of the screw S and attaching a reduced threaded end of the invention mixer apparatus therein.

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Considering in further detail the basic component assembly shown in Figure ]., numeral l denotes a main shalt having a reduced threaded extremity lo which is securely engaged in an internally threaded end of screw S. An opt posit end of main shaft 1 has integrally formed therewith shear ring portion lo. Located around shalt 1 in spaced relation thereto is a stationary shear control sleeve 2.
This sleeve 2 is fixed against an inner peripheral surface of the barrel B. This may be accomplished, for example, by lo forming sleeve 2 of a metal having a coefficient of expansion greater than the coefficient of expansion of the petal in barrel B.
Sleeve 2 is also positioned with one end in abutting relation to the shear ring portion lo. At an opposite end of sleeve Andy in abutting relationship therewith is a separately formed shear ring element 3 which is solidly secured between the extrude screw S and an annular shoulder portion lo of shaft 1 and is rotatable therewith.
This basic component assembly including the main shaft l, sleeve 2 and shear ring means and lo is also shown in Figures 2, 3 and 4 combined with other modular components for another processing mode and is still further shown in Figures 21-23 combined with different component means and still other processing modes.
It will be understood that opposite ends of the stationary sleeve 2 will be subjected to wear when the shear ring portions lo and separately formed shear ring 3 are being rotated by main shaft 1. To prevent such wear the sleeve

2, in one preferred embodiment, may have opposite ends :
thereof provided with hardened bearing portions as PA and 2B.

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Extending inwardly of sleeve 2 and downwardly from the hardened bearing-portions 2B is a conical surface 2C. Similarly, extending inwardly and downwardly from bearing PA is another conical surface ED. These conical surfaces are formed to provide for controlling the thick-news of luminary displacement carried out by movement of the shear ring 3 and shear ring portion lo. Increasing or decreasing the depth of these conical surfaces varies the thickness of each luminary cut off by a blade and provides a desirable range of thickness controlled.
As noted above, the sleeve 2 has an inner port-furl surface occurring in spaced relation to the main shaft 1 and this inner peripheral surface is further con-strutted with spaced apart axially extending grooves as 2G, more clearly shown in Figures 4 and 9. These grooves function to receive sheared portions of fluid material cut of by the shearing blades and to provide for a plurality of streams of materiel being diverted and guided along a plurality of linear paths of travel between the sleeve and the shaft 1.
An important feature of the invention is the come bination of a stationary sleeve having conical shear con-trot surfaces and flow diverting grooves as described above with spaced apart shear ring means of a unique construction.
Thus, the shear ring 3 is formed with radially extending shearing blades as PA, 3B, 3C, etc. These shearing blades are spaced apart to provide passageways through which extruded material may pass. Extending between the blades PA, 3B, 3C, etc. are inwardly inclined sloping surfaces as ED, YE, OF, etc. Similarly, the shear ring portion lo is formed with radially extending shearing blades as lo, if, lo, Sue etc. and are spaced apart to provide passageways for fluid flow and extending between the blades are sloping surfaces lug, lo, lit etc. which are inclined upwardly, as shown more clearly in Figures 4 and 11, The arrangement of parts of Figures 4 and if is also shown diagrammatically in Figure 12.
As a result of this arrangement of parts there is realized periodically undulating flow of material which is successively interrupted to undergo luminary displacement and thereby an intensified mixing is achieved. This in-tensified mixing is highly effective in subdividing material which is not in a fluid state and which may tend to accumu-late at points near the end of an extrude screw as indicated in Figure 2.
In operating the apparatus of Figure l a helically moving extruded mass of fluid material is advanced through the extrude barrel B by the extrude screw S and portions of the helically moving mass move into the spaces between the blades of-shear ring 3. Figure 13 illustrates the port lions of material in diagrammatic form.
Immediately thereafter these portions of material are subjected to luminary displacement. The thickness of each of the laminate displaced is regulated by the depth of the conical surface ED of sleeve 2.
Thereafter, the displaced material becomes guided along grooved surfaces of sleeve 2 as spaced apart streams of material which travel in linear paths of relatively short axial length. Figure 14 shows diagrammatically these swoop crated streams of material denoted by reference characters Ml, My, My, My, My and My.

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Thereafter, the streams of material are con-tenuously subdivided by a second stage of luminary disk placement carried out by shear ring portion lo. Figure 15 indicates diagrammatically flow of displaced maternal My.
Portions of material thus subdivided is merged together in a helically moving mass My as suggested die-grammatically in Figure 16 and quickly undergoes another step of luminary displacement by shear ring 7 as indicated diagra~natically by portions of material MY in Figure 17.
In the processing mode illustrated in Figure 1 the metering module 4 discharges the finally mixed and blended product described which is shown for example at the end of the apparatus illustrated in Figure 2.
In Figure 4 there is illustrated a processing mode by means of which increased shearing and mixing may be carried out depending upon the material being dealt with. In this modular mixing apparatus the same component assembly is employed including the main shaft 1, sleeve 2 and shear ring means 3 and lo.
However, in place of the metering screw 4 there is attached another shear ring member 7 having a threaded end 7' which is threaded into the internally wormed threads of ring portion lo to become rotatable therewith. the member 7 is formed with internally constructed threads as OH and have outwardly projecting shearing blades as AYE, 12B, 12C, etc. These blades, unlike the blades of ring portion lay are not parallel to the central axis of the extrude screw but are skewed and extend angularly with no-spent to the central longitudinal axis of the ring 7.

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It has been found that an acceleration flow of material may be realized by these angularly disk posed blades. Also, desirable results may be obtained by combining these shearing blades with another sleeve member 6 to carry out a progressively extended stage of shearing as member 7 is rotated around the end of the sleeve 6 which has hardened the bearing portions as PA
and 6B earlier described. It will also be noted that the thickness of luminary displacement of fluid material is again regulated by conical surfaces as ED.
Still another stage of shearing is obtained by the use of a diffuser tip 5 which has spaced apart shearing blades rotatable around the sleeve 6. The member 5 is formed with a threaded end YE which is de-teachably secured in threaded relationship with member Thea member 5 is also shaped with a conical end face and material passing through the openings denoted by arrow 5 in the extrude tip tend to be forced along converging paths of travel for desirable communication with the die member.
Material passing through the blades of shear ring 7 again enter a the stationary sleeve 6 and quickly undergo another step of luminary displacement by shear ring 7 and become guided along the grooved surfaces of the stationary sleeve 6 to provide spaced apart streams as suggested diagrammatically in Figure 18 and diluted by the reference characters My, My, My, Moo, MU and M12.

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A final step of luminary displacement to sub-divide these streams of material is carried out by move-mint of the dispersing tip 5 against the stationary sleeve 6 and this provides portions as MY indicated diagrammatic gaily in Figure 19. A resulting mixture MY is then led through the dispersing tip and leaves the tip as a con-verging stream indicated by the arrows in Figure 20. In Figure 21 another mode of mixing has been illustrated in which there is employed the same basic component assembly including parts 1, 2, 3, and lo; however in place of the second shear ring 7 there is mounted in the threaded end of shear ring lo a kneading rotor denoted by numeral 8 which is rotatable against the stationary sleeve 6, as shown in Figures 21, 22 and 23. The kneading rotor come potent 8 is formed with a threaded end PA and is provided with internal threads 8B.- It will be noted that the kneading rotor is constructed with oblong shaped bars or arms which extend radially outward and occur in angularly disposed relationship with respect to one another, as shown in Figures 4, 21, 22 and 23. It has been found that a kneading and and stretching of some fluid masses at this point in the processing can be carried out to provide further desirable attenuation and mixing of certain fluid materials.

Claims (22)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE LO
CLAIMED ARE DEFINED AS FOLLOWS:

1. Improved modular mixing apparatus for use with an extrude screw and barrel assembly to extrude fluid material, said apparatus including a rotatable driver shaft having a threaded end for engagement with the extrude screw, stationary sleeve means located around the driver shaft in spaced relation thereto and presenting opposite bearing ends, shear ring elements rotatable with the driver shaft and occurring in abutting relationship to the opposite bearing ends of the stationary sleeve, and fluid processing means detachably connected to the driver shaft.

2. The invention of claim 1 in which one of the shear ring elements is formed integrally with the driver shaft and is further provided with an internally threaded portion in which the fluid processing means is detachably secured.

3. The invention of claim 2 in which the fluid processing means includes an additional shear ring clement and fluid discharge means.

4. The invention of claim 3 in which the fluid processing means further includes a fluid kneading rotor detachably secured between the additional shearing means and the fluid discharge means.

5. The invention of claim 4 in which the fluid processing means further includes a stationary sleeve detachably secured between the kneading rotor and the fluid discharge means.

6. The invention of claim 5 in which the fluid discharge means consists in a rotating fluid dispersing tip.

7. The invention of claim 1 in which the stationary sleeve is internally recessed to form axially extending grooves along which spaced apart streams of fluid material may be guided.

8. The invention of claim 1 in which the stationary sleeve is internally recessed to form axially extending grooves along which spaced apart streams of said fluid material may be guided, one of said shear ring elements constructed with spaced apart shear ring blades through which sheared material is directed into the axially extending grooves, and said bearing ends of the stationary sleeve having inner peripheral surfaces thereof formed with conical portions.

9. Improved modular mixing apparatus for use with an extruder screw and barrel assembly, said apparatus including a rotatable driver shaft having a threaded end for engagement with the extruder screw, stationary sleeve means located around the driver shaft in spaced relation thereto and presenting opposite bearing ends, shear ring elements rotatable with the driver shaft and occurring in abutting relationship to said opposite bearing ends of the stationary sleeve, one of said shear ring elements being detachably secured to the driver shaft and the other of the said shear ring elements being formed integrally with the driver shaft, and fluid processing means detachably connected to the driver shaft, one of said shearing elements being formed integrally with the driver shaft and being further provided with an internally threaded portion in which the fluid processing means is detachably secured and said fluid processing means including additional shearing means in threaded engagement with the said integrally formed ring element of the driver shaft, a fluid dispersing tip in threaded engagement with the additional shearing means and a stationary sleeve fixed between the dispersing tip and the said additional shearing means.

10. Improved modular mixing apparatus for use with an extruder screw and barrel assembly, said apparatus including a rotatable driver shaft having a threaded end for engagement with the extruder screw, stationary sleeve means located around the driver shaft in spaced relation thereto and presenting opposite bearing ends, shear ring elements rotatable with the driver shaft and occurring in abutting relationship to said opposite bearing ends of the stationary sleeve, one of the shear ring elements being detachably secured to the driver shaft and the other of the said shear ring elements being formed integrally with the driver shaft, and fluid processing means detachably connected to the driver shaft, one of the shear ring elements being formed integrally with the driver shaft and formed with an internally threaded portion in which the fluid processing means is detachably secured, said integrally formed shearing element presenting shearing blades which are spaced apart by surfaces which converge with respect to the central axis of the driver shaft, a separately formed shearing element located around a reduced portion of the driver shaft and rigidly held between the driver shaft and the extruder screw, said separately formed shearing ring element presenting shearing blades which are spaced apart to define surfaces which converge with respect to the central axis of the driver shaft.

11. Improved modular mixing apparatus for use with an extruder screw and a barrel in which a fluid body is confined and moved in a helical direction, said apparatus comprising a combination of shearing components arranged to constitute a shearing module and including a driver shaft having a threaded extremity engageable within the extruder screw and rotatable therewith, an opposite extremity of the driver shaft being formed with a shear ring portion and presenting spaced apart shearing blades which are separated by surfaces which converge with respect to the central axis of the driver shaft, a sleeve member located in spaced relationship around the driver shaft and fixed inside the extruder barrel in abutting relation to the shearing blades, a separately formed shear ring element supported on a reduced drive shaft part and rigidly held on the drive shaft against an end of the said thermal control sleeve, said separately formed shear ring element having spaced apart shearing blades and surfaces therebetween which diverge with respect to the central axis of the driver shaft and a dispersing tip element detachably secured in the said shear ring portion of the driver shaft.

12. Improved modular mixing apparatus for use with an extruder screw and barrel assembly, said apparatus including a rotatable driver shaft having a threaded end for engagement with the extruder screw, stationary sleeve means located around the driver shaft in spaced relation thereto, shear ring elements rotatable with the driver shaft and occurring in abutting relationship to opposite ends of the stationary sleeve, and fluid processing means detachably connected to the driver shaft, one of said shear ring elements being separately formed and presenting spaced apart shearing blades separated by guide surfaces which converge with respect to the central axis of the driver shaft, the other of the shear ring elements being formed as an integral part of the driver shaft and presenting shearing blades separated by surfaces which diverge with respect to the central axis of the driver shaft, said stationary sleeve means being formed with axially extending grooves and said sleeve and shear ring elements cooperating to produce an undulating flow of material between the sleeve and the driver shaft in an undulating linear path of travel.

13. A method of processing a fluid mixture in a modular mixing apparatus characterized by dividing a helically moving mass of the fluid mixture into a plurality of circumferentially spaced apart streams of material, guiding the spaced apart streams of material along generally axially paths of travel and then cutting the spaced apart streams of material to carry out subdivision of the separated streams of material, then discharging the subdivided material as a homogeneous mass into a die member.

14. A method of processing a fluid mixture in a modular mixing apparatus characterized by dividing a helically moving mass of the fluid mixture into a plurality of circumferentially spaced apart streams of material, guiding the spaced apart streams of material along undulating linear paths of travel of relatively short axial length, cutting the spaced apart streams of material to carry out subdivision of the separated streams of material and then discharging the subdivided material into a die member.

15. The method of claim 14 in which the fluid mixture as it enters the modular mixing apparatus includes substances which are not in a fluid state and the finally subdivided material is emitted as a mixture in which substances not in a fluid state are homogeneously dispersed throughout the fluid mixture.

16. The method of claim 13 in which the subdivided stream of material is subjected to still further cutting and moved along linear paths of travel and is then brought together to form a homogeneous mixture.

17. A method of processing a fluid mixture by means of an extruder apparatus which includes an extruder screw, a barrel in which the screw is mounted for rotative movement and a modular mixing apparatus attached to the extruder screw characterized in that a helically moving mass of the fluid mixture leaving the extruder is brought into contact with rotating shear ring means to cut off portions of the mixture, is then guided through a stationary sleeve along spaced apart undulating paths of travel of relatively short axial length, thereafter is subjected to further cutting and is finally discharged into a die member.

18. A method of processing a fluid mixture in a modular mixing apparatus characterized in cutting a helically moving mass of the fluid mixture to separate portions of the mixture into a plurality of separated streams of material, guiding the streams of material along undulating linear paths of travel of relatively short axial length and then subjecting the separated streams of material to further mixing and cutting and discharging the resulting mixture as a homogeneous mass.

19. The method of claim 13 in which the subdivided streams of material are subjected to a rotary kneading treatment and then undergo additional cutting and are again separated into spaced apart streams of material which are displaced and blended together to form a homogeneous mass.

20. A method of processing a fluid mixture comprising: driving a fluid mixture by means of an extruder screw through a helical path; subdividing the fluid mixture into a plurality of circumferentially displaced flow segments;
bringing the individual flow segments into contact with a shaft rotating relative to the flow segments; and subdividing the flow segments by cutting across the flow segments.

21. A method as claimed in claim 20 wherein the fluid flow segments flow through channels formed by an undulating inner surface of a ring surrounding the shaft and forming channels of semicircular cross section about the shaft.

22. A method as claimed in claim 21 wherein the ring is positioned within an extruder barrel and the shaft is coupled to the extruder screw.