Apparatus and method for degassing a plasticized material

Abstract

Apparatus for degassing a plasticizable material, wherein the apparatus has at least one passage having a inlet opening for the feed of the material in the plasticized state. Provided downstream of the at least one passage in the flow direction of the plasticized material is a plurality of substantially parallelly arranged partial passages so that a material flow flowing through the passage is split up into partial flows by the partial passages, and the partial passages open into a free space so that the material expands in the free space, wherein at least one of the partial passages has a taper.

Claims

1. An apparatus for degassing a plasticizable material, comprising: at least one essentially vertical passage having a first inlet opening for a feed of the material in a plasticized state; a plurality of substantially parallelly arranged vertical partial passages downstream of the at least one essentially vertical passage in a flow direction of the plasticized material so that a material flow flowing through the at least one essentially vertical passage is split up into partial flows by the vertical partial passages, wherein the vertical partial passages open directly into a free space such that the plasticized material of the partial flows free-falls vertically from the partial passages into the free space, the free space having a vertical dimension which allows strands of the plasticized material to enlarge during free-fall such that gas dissolved in the plasticized material is released in the free space; and a feed device having a second inlet opening, wherein the second inlet opening is provided in a region of the free space, and the feed device is configured to feed at least one additive or a further plasticizable material to the plasticized material via the second inlet opening, wherein at least one of the partial passages has a taper.

2. The apparatus as set forth in claim 1, wherein the taper has a conical region or a rounded protrusion.

3. The apparatus as set forth in claim 2, wherein the taper has the conical region, and the conical region tapers in the flow direction of the plasticized material.

4. The apparatus as set forth in claim 1, wherein at least one of the partial passages has a longitudinal axis and a mandrel which is oriented substantially parallel to the longitudinal axis.

5. The apparatus as set forth in claim 4, wherein lateral surfaces project from the mandrel along the flow direction of the plasticized material.

6. The apparatus as set forth in claim 5, wherein the lateral surfaces project from the mandrel in the flow direction of the plasticized material at an end of the mandrel.

7. The apparatus as set forth in claim 4, wherein the mandrel has at least one injection nozzle device, and wherein a fluid can be fed to the plasticized material by way of the at least one injection nozzle device.

8. The apparatus as set forth in claim 4, wherein a gap is formed between the mandrel and the at least one of the partial passages having the mandrel, and wherein the gap has a size of 0.05 mm to 3 mm.

9. The apparatus as set forth in claim 8, wherein the mandrel is mounted moveably along the longitudinal axis and is moveable or can be arrested in its position.

10. The apparatus as set forth in claim 9, wherein the size of the gap is adjustable to a size in a range of 0.05 mm to 3 mm.

11. The apparatus as set forth in claim 8, wherein the gap is an annular gap and has a size of 0.5 mm to 1 mm.

12. The apparatus as set forth in claim 4, wherein in the at least one of the partial passages having the mandrel, the mandrel is centrally arranged in the at least one of the partial passages.

13. The apparatus as set forth in claim 1, wherein the at least one of the partial passages has a further taper.

14. The apparatus as set forth in claim 13, wherein the further taper has a conical region or a rounded protrusion.

15. The apparatus as set forth in claim 1, wherein a projection is arranged transversely to the flow direction in the free space of the apparatus downstream in the flow direction of at least one of the partial passages.

16. The apparatus as set forth in claim 15, wherein the projection is configured to cut open a strand of the plasticized material falling from the at least one of the partial passages.

17. The apparatus as set forth in claim 1, wherein the free space is gas-tight in relation to an environment of the apparatus.

18. The apparatus as set forth in claim 1, wherein the at least one of the partial passages has a minimum diameter of 0.2 mm to 10 mm.

19. The apparatus as set forth in claim 18, wherein the at least one of the partial passages has a minimum diameter of 0.3 mm to 5 mm.

20. The apparatus as set forth in claim 19, wherein the at least one of the partial passages has a minimum diameter of 0.5 mm to 3 mm.

21. The apparatus as set forth in claim 1, wherein the at least one of the partial passages has a length and a minimum diameter, and wherein the length is in a ratio of smaller than 2 relative to the minimum diameter.

22. The apparatus as set forth in claim 1, wherein the at least one of the partial passages viewed in the flow direction has a polygonal cross-sectional shape.

23. The apparatus as set forth in claim 22, wherein the at least one of the partial passages viewed in the flow direction has a rectangular cross-sectional shape.

24. The apparatus as set forth in claim 1, wherein the apparatus is in the form of a feed device for an injection unit for a shaping machine.

25. The apparatus as set forth in claim 1, further comprising at least one evacuation device adapted to carry gases out of the apparatus in a region of the free space.

26. The apparatus as set forth in claim 1, further comprising at least one measuring device provided in a region of the free space, wherein the at least one measuring device is adapted to determine a viscosity or a temperature or a color or a flow speed of the plasticized material.

27. The apparatus as set forth in claim 1, wherein the partial passages open into the free space at an angle of between 0 degrees and 90 degrees in relation to a horizontal direction.

28. A plasticizing assembly for a shaping machine comprising: a plasticizing unit; an injection unit; and the apparatus of claim 1, wherein an outlet opening of the plasticizing unit for plasticized material is connected in a flow relationship to the first inlet opening of the apparatus and the free space is connected in a flow relationship to a barrel cylinder of the injection unit.

29. A shaping machine comprising the plasticizing assembly as set forth in claim 28.

30. A method of degassing a plasticizable material using the apparatus as set forth in claim 1, the method comprising: feeding plasticized material to the at least one essentially vertical passage by way of the first inlet opening; splitting the material flow flowing through the at least one essentially vertical passage up into partial flows by the vertical partial passages in a flow direction of the plasticized material downstream of the at least one essentially vertical passage; and passing the material flow flowing through the at least one essentially vertical passage into the free space by way of the vertical partial passages, wherein the plasticized material expands in the free space, wherein the plasticized material when flowing through at least one of the vertical partial passages is viscoelastically loaded by a taper so as to increase a strand enlargement which occurs in the free space relative to a strand enlargement which would occur in the absence of the taper.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Further examples, advantages and details of the invention are set forth in the specific description hereinafter and illustrated in the Figures in which:

(2) FIG. 1 shows a first embodiment of an apparatus according to the invention,

(3) FIG. 2 shows a first embodiment of a taper,

(4) FIGS. 3a-3g show various variants of a taper, and

(5) FIG. 4 shows a shaping machine with an embodiment of an apparatus according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a first embodiment of an apparatus 1 according to the invention, wherein a plasticized material 2 can be fed to the apparatus 1 by way of a passage 3.

(7) That passage 3 passes the plasticized material 2 in a vertical direction to the partial passages 6.

(8) The plasticized material 2 can be fed to the apparatus 1 by way of the inlet opening 4 to the passage 3, wherein the plasticized material 2 can be passed to the inlet opening 4 for example from a plasticizing unit 21.

(9) After the plasticized material 2 has been transferred from the passage 3 into the partial passages 6 the mass flow of the plasticized material 2 is distributed to the partial passages 6 from the passage 3.

(10) The partial passages 6 end in a free space 7, in which case the plasticized material 2 transitions in free fall vertically into the free space 7, in which case the transition out of the partial passages 6 into the free space 7 affords a strand enlargement of the plasticized material 2, as is later illustrated and discussed in more detail in FIGS. 2 and 3a-3g.

(11) By virtue of the strand enlargement and the simultaneous viscoelastic relief of load on the plasticized material 2 gas dissolved in the plasticized material at the beginning forms bubbles which escape from the plasticized material 2 in free fall through the free space 7. A similar thing occurs with gas already previously included in the plasticized material in bubble form.

(12) The gas removed from the plasticized material in that way is then present in the free space 7.

(13) The gases which are degassed from the plasticized material 2 can be carried away from the free space 7 by way of the evacuation device 18.

(14) The evacuation device 18 operates by means of a suction removal pump 23.

(15) Alternatively the gases removed from the plasticized material can escape passively from the free space 7.

(16) In a condition of free fall or flowing into the free space 7 the plasticized material 2 is fed from the partial passages 6 to an injection unit 14 of a shaping machine 15, wherein the plasticized material is fed through an opening in a barrel cylinder 16 to the injection unit 17 which is in the form of an injection screw (actually: it drops on to same).

(17) The apparatus further has a feed device 24, by means of which an additive 25 or a further plasticizable material can be fed to the plasticized material 2 by way of the further inlet opening 19 and the free space 7 in order then to be blended together jointly with the plasticized material in the injection unit 17 (more precisely: the injection screw).

(18) A measuring device 20 is also arranged in the free space 7, in the form of an optical measuring device 20.

(19) A state and/or a flow rate and/or a color of the plasticized material 2 can be determined by way of the optical detection of that measuring device 20.

(20) Thus it is for example certainly conceivable that a color of the plasticized material 2 is detected by way of the optical measuring device 20, in which case a closed-loop controlled amount of additives 25 for coloring the plasticized material 2 could be fed into the free space 7 under the control of the feed device 24.

(21) In order to promote the strand enlargement effect of the plasticized material 2 on issuing from the partial passages 6 into the free space 7 the partial passages 6 in this embodiment have a constriction or taper 8, as is described in greater detail with reference to FIG. 2.

(22) FIG. 2 represents an enlarged detail view of a partial passage 6 from FIG. 1, with plasticized material 2 being passed through the partial passage 6 in the flow direction 5.

(23) In this embodiment the flow direction 5 of the plasticized material 2 corresponds to the longitudinal direction of the partial passage 6 and in addition a vertical direction in an operating state of the apparatus 1.

(24) The partial passage 6 of the embodiment in FIG. 2 has a taper 9 formed by a conical region 9. That conical region which tapers in the flow direction 5 leads to viscoelastic stressing of plasticized material 2, which promotes strand enlargement at the transition into the free space 7 of the plasticized material 2.

(25) The strand enlargement provides that the surface of the plasticized material 2 is torn open on issuing from the partial passage 6 and gasses dissolved in the plasticized material 2 are liberated, leading to degassing of the plasticized material 2.

(26) That flow behavior on the part of the plasticized material 2 can thus ideally be used to degas the plasticized material 2, in which case more dissolved gasses can be extracted from the plasticized material 2, the correspondingly greater that the strand enlarges.

(27) In order further to promote that effect the FIG. 2 embodiment has a further taper 12 which is afforded by the rounded recess 13.

(28) That rounded recess 13 leads to a further (dynamic) viscoelastic loading of the plasticized material 2 and thus increases the effect of strand enlargement when the plasticized material 2 issues from the partial passage 6 into the free space 7.

(29) In this embodiment the rounded recess 13 is of a cross-section in the shape of a segment of a circle. It will be appreciated that other cross-sectional shapes are certainly conceivable, for example a segment of an ellipse or more generally of an oval. In that respect it is not absolutely necessary that the cross-section is symmetrical in relation to a horizontal axis in FIG. 2. For example it would also be possible to use a segment of a kidney-shaped cross-section.

(30) The partial passage 6 in this embodiment has a minimum diameter D (in a horizontal cross-section through the further taper 12) and a length L (along the flow direction 5 or the longitudinal axis 11).

(31) FIGS. 3a through 3d show different alternative variants of the partial passage 6, while FIG. 3a shows the variant of FIG. 2 once again.

(32) The variant in FIG. 3b represents a partial passage 6 which has only one taper 8 in the form of a conical region 9.

(33) This variant in FIG. 3b can be expanded by a mandrel or torpedo arranged centrally in the interior of the partial passage 6, as shown by FIG. 3c.

(34) The mandrel 10 can cause an additional open surface in respect of the plasticized material 2, and that in turn serves for better degassing.

(35) It has proven to be particularly desirable if that mandrel 10 is provided in a lower region with fins (as can be seen from FIG. 3c) which knife-like cut up the plasticized material 2 after issuing from the at least one partial passage 6 and thus promote the escape of gas from the plasticized material 2.

(36) It is certainly conceivable for the mandrel 10 to be of a configuration with a conical enlargement (as indicated by FIG. 3c), in which case it is possible to promote swelling of the plasticized material 2 on issuing from the partial passage 6.

(37) As shown in FIG. 3d however it can also be provided that a partial passage 6 has a first taper 8 and a further taper 12, wherein the taper 8 and the further taper 12 are respectively afforded by way of a conical region 9 which decreases along the flow direction 5. The further taper 12 also dynamically enhances the viscoelastic loading on the plasticized material shortly before issuing into the free space 7.

(38) The mandrel 10 can be without fins, as can be seen from FIG. 3d.

(39) It can advantageously be provided that the mandrel 10 is mounted moveably along the longitudinal axis 11 and is moveable and/or can be arrested in its position. That adjustment possibility can provide that a gap 36 is adjustable between the mandrel 10 and the inside wall of the partial passage so that adjustment can be effected individually (depending on the respective material to be processed as the plasticized material 2).

(40) Further structures are also conceivable in relation to the configuration of the partial passages 6. For example the further taper 12 and/or the rounded portion 13 could be implemented by a thickening on the mandrel 10.

(41) It can also be provided that the mandrel 10 has an injection nozzle device at the end (see in that respect also FIG. 3g), whereby a fluid 37 (for example a gas) can be fed to the plasticized material 2. Such an injection nozzle device can be for example in the form of a tube by a suitable configuration of the mandrel 10.

(42) The feed of gases by way of the mandrel 10 can additionally increase or promote the swelling of the plasticized material 2 on issuing from the partial passage 6.

(43) In addition additives (for example in the form of a propellant gas) can be fed to the plasticized material 2 by the feed of gases by way of the mandrel 10, like for example aromatic substances or entrainment agents. By way of example active gases like CO.sub.2 can be used to bind fragrances dissolved in the plasticized material.

(44) By way of example fluid additives or additions (like hardeners, plasticizers, dyestuffs and so forth) could be fed by way of an injection nozzle device of the at least one mandrel 10, which would afford the substantial advantage that the plasticized material encloses the added fluid additive or addition (which for example on the one hand is advantageous for thorough mixing of the plasticized material with the fluid additive or addition while on the other hand preventing uncontrolled spreadsplashing aroundof the fluid additives or additions in the feed in the free space).

(45) FIG. 3e shows a configuration in which the partial passage 6 has a first taper 8 and a further taper 12, wherein the taper 8 and the further taper 12 are respectively provided by way of a rounded region which reduces along the flow direction 5. The further taper 12 also dynamically increases the viscoelastic loading of the plasticized material shortly before issuing into the free space 7.

(46) Those rounded narrowing regions 8, 12 can be for example in accordance with a hyperbolic function of the cross-section along their longitudinal axis so that a strain rate of the plasticized material 2 is kept constant along the narrowing regions 8, 12.

(47) FIG. 3f shows a variant of the partial passage 6 in which the first narrowing region 8 is in the form of a conical region 9 and the narrowing second region 12 is of a rounded configuration.

(48) FIG. 4 shows a shaping machine 15 having a plasticizing assembly 22 which has an embodiment of an apparatus 1 according to the invention.

(49) FIG. 4 diagrammatically shows a shaping machine 15. That shaping machine 15 has a plasticizing assembly 22 and a closing unit 26, which are also arranged on a machine frame 27.

(50) The closing unit 26 has a stationary mold mounting plate 28, a moveable mold mounting plate 29 and an end plate 30.

(51) In contrast to the illustrated horizontal three-plate machine the closing unit 26 could also be in the form of a two-plate machine or a vertical machine.

(52) The moveable mold mounting plate 28 is moveable relative to the machine frame 27 by way of a drive device 31. Such a drive device 31 can for example have a toggle lever mechanism.

(53) Mold halves of a shaping tool 32 can be mounted or fitted to the fixed mold mounting plate 28 and the moveable mold mounting plate 29 (this is shown in broken line).

(54) The illustrated shaping tool 32 which is closed in FIG. 4 has at least one cavity. An injection passage, by way of which a plasticized material of the plasticizing assembly 22 can be fed, leads to the cavity.

(55) The plasticizing assembly 22 has a continuous plasticizing unit 21 which is in the form of a single-screw extruder and by way of which a recycling material can be supplied. The plasticizing unit 21 plasticizes the material to be plasticized and passes the plasticized material by way of a melt filter 33 into an apparatus 1 for degassing the plasticized material.

(56) That apparatus 1 can be implemented for example like the apparatus 1 shown in FIG. 1.

(57) Subsequently to the apparatus 1 for degassing the plasticized material 2 the plasticized material 2 is fed to the injection unit 14, wherein the plasticized material 2 is passed through an opening in a barrel cylinder 16 to the injection unit 17 in the form of a single-screw injector.

(58) The injection unit 17 in this embodiment has a barrel cylinder 16 and an injection screw arranged therein. That injection screw is rotatable about its longitudinal axis and is moveable axially in the injection direction along the longitudinal axis.

(59) Those movements are initiated by way of a diagrammatically illustrated drive unit 35. Preferably the drive unit 35 includes a rotary drive for the rotary movement and a linear drive for the axial injection movement.

(60) The plasticizing assembly 22 is connected in signal-conducting relationship to an open-loop or closed-loop control unit 34. Control commands are output to the plasticizing assembly 22 by the open-loop or closed-loop control unit 34.

(61) The open-loop or closed-loop control unit 34 can be connected to an operating unit or can be an integral component part of such an operating unit.

(62) The apparatus 1 according to the invention makes it possible to degas a plasticized material 2 (for example a recycled material) which is charged with unwanted gases, in such a way that it can be used for example in a per se known injection molding process for the production of moldings so that the unwanted gases have no or at least a significantly reduced influence on the moldings.

LIST OF REFERENCES

(63) 1 apparatus 2 plasticized material 3 passage 4 inlet opening 5 flow direction 6 partial passage 7 free space 8 taper 9 conical region 10 mandrel 11 longitudinal axis 12 further taper 13 rounded recess 14 injection unit 15 shaping machine 16 barrel cylinder 17 injection unit 18 evacuation device 19 further inlet opening 20 measuring device 21 plasticizing unit 22 plasticizing assembly 23 suction pump 24 feed device 25 additive 26 closing unit 27 machine frame 28 fixed mold mounting plate 29 moveable mold mounting plate 30 end plate 31 drive device 32 mold tool 33 melt filter 34 open-loop or closed-loop control unit 35 drive unit 36 gap 37 fluid