CN102413995A

CN102413995A - Honeycomb extrusion process and apparatus

Info

Publication number: CN102413995A
Application number: CN2009801590681A
Authority: CN
Inventors: D·W·库洛贝特; D·M·诺尼; B·V·斯瓦纳马尼
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2009-02-27
Filing date: 2009-02-27
Publication date: 2012-04-11
Also published as: WO2010098736A1

Abstract

Honeycomb extrudate of improved quality is extruded from plasticized ceramic-forming mixtures (30) utilizing an extruder (12) joined to a honeycomb extrusion die (14) through a connecting enclosure (16) provided with a friction-reducing inner surface, that surface (24) being effective to improve the peripheral flow of the mixture (30) to the die.

Description

Honeycomb ceramics extrusion method and equipment

Technical field

Method and apparatus as herein described relates to the technical ceramics field, is particularly suitable for being used for making ceramic structure through the pottery formation mixture of powders of plasticising is extruded through extrusion die, for example the ceramic main body of honeycomb ceramics and so on.

Background technology

People are known to make ceramic honeycomb structure through the method that may further comprise the steps: the pottery of preparation plasticising forms mixture of powders; Said mixture is extruded through the honeycomb ceramics extrusion die; To form the honeycomb ceramics squeeze-up; Then said squeeze-up is carried out drying and fires, make firm refractory honeycomb body structure.The ceramic honeycomb structure of making thus is widely used as the base material of supported catalyst at present, is used for to for example handling from the burnt gas of motor vehicles, also as the porous wall-flow filter, is used for capturing the exhaust gas particle from for example Diesel engine.

The initial application of such honeycomb ceramics is to be used for handling automobile exhaust gas, and in the case, less lighter structure just is enough to the enough catalyst of load, is used for from waste gas stream, removing carbon monoxide, nitrogen oxide and unburned hydro carbons basically.People need successfully make much bigger honeycomb ceramics through extrusion molding, obtain marked improvement with respect to prior art.

Make the bigger problem that honeycomb ceramics brought and be geometry and globality retentive control product.Under the bigger honeycomb ceramics size condition of extruding, some faults of construction appear through regular meeting, comprise the distortion of duct or passage, inner channel walls defective, and blemish, for example surface or crust cracking may be difficult to control especially.

When making bigger honeycomb ceramics, in wet squeeze-up, possibly produce big radial oriented surface or crust crackle, these crackles possibly extend to darker position, honeycomb ceramics inside from the surface.Because the cracking problem possibly be intermittent in production operation at first, occur at random, but through regular meeting along with production operation is proceeded, occur subsequently, it is more serious that degree becomes, the cause that therefore will diagnose these defectives is very complicated.

Summary of the invention

Method as herein described comprises a kind of method of extruding main body that is used for forming; This method may further comprise the steps: apply active force and force pottery to form material along extruding direction through tube-like envelope and through extrusion die, said tube-like envelope comprises the inner surface of reducing friction.The specific embodiment of these methods comprises through following steps; Form mixture of powders by the pottery of plasticising and form the honeycomb ceramics squeeze-up:, said plastic mixture is transferred to the honeycomb ceramics extrusion die from extruder through having the connection shell of the inner surface of reducing friction.

Method of the present invention comprises some embodiments, and wherein said inner surface of reducing friction comprises a plurality of protrusions, and said protrusion limits a plurality of grooves or depression on said inner surface.Said protrusion can comprise ridge, and said groove can comprise ditch, and said depression can comprise depression.The pottery that these methods that plastic mixture is transported to extrusion die from extruder can reduce or eliminate plasticising during connecting shell forms the variation that the material stream of material possibly occur; Said variation causes owing to contacting with shell wall, perhaps causes owing to other reason.

The equipment that is used for realizing said process modification comprises that the pottery with cause plasticising is formed mixture of powders to be made the equipment of honeycomb ceramics squeeze-up and improve; Promptly this equipment comprises extruder, honeycomb ceramics extrusion die and connects shell; Said connection shell links to each other said extruder with die head, be used for the pottery formation mixture of plasticising is carried between the two at this.The embodiment of this equipment comprises the connection shell of the inner surface that has combined to reduce friction.

In some embodiments, through superficial layer, for example coating or shell lining provide said inner surface of reducing friction, said coating or shell lining by form be different from said housing main body or the surface below solid material form.The coefficient of friction of employed material is less than housing main body or the coefficient of friction below the surface.In other embodiment, said inner surface of reducing friction has the inner surface of veining, designs said texture and is used for reducing when mixture is transported to extrusion die, and the pottery of said plasticising forms the contact area between mixture and the inner surface of outer cover.In other embodiment, can adopt the combination of the internal table surface layer of low-friction material with texturizing surfaces.

The accompanying drawing summary

Further shown method and apparatus of the present invention below in conjunction with accompanying drawing, among the figure:

Fig. 1 is used for extruding through honeycomb die the sketch map of the conventional equipment of making the honeycomb ceramics squeeze-up;

Fig. 2 is the sketch map of an embodiment of connection shell as herein described;

Fig. 3 a-3c shows the enlarged diagram in the cross section on the surface of reducing friction that can be used in combination with the shell of Fig. 2;

Detailed Description Of The Invention

We have confirmed in big honeycomb ceramics squeeze-up, to produce the possible factor of face crack at present, promptly leave the flow velocity of squeeze-up or the reducing greater than expection level of extruded velocity of die head periphery with the peripheral section of formation shaping honeycomb ceramics squeeze-up.Squeeze-up flows to the slower flow velocity of said squeeze-up surface or outer skin portion and combines with higher flow velocity through the extrusion die core, if flow velocity differs enough greatly, may produce face crack.Carried out further research based on this discovery; The result finds that the mixture of powders of plasticising tends to produce slow flow region; Even can stop up the position around the perimeter of honeycomb ceramics extrusion die inlet face, even also this kind situation can take place after short production at interval.Discovery is under slower rate of extrusion condition, and this kind effect can increase.Also find on the whole diameter of die head inlet face, comparatively even through the initial flow rate of die head.

Present analysis shows that the flowing effect that occurs at the honeycomb ceramics extrusion die upper reaches might be included in the generation of slow peripheral flow and die head obstruction.Although it is without wanting to be limited by theory; But think in the process that is transported to the extrusion die inlet through attaching parts; Because the pottery of plasticising forms the rubbing action between mixture and the connector wall; Make the piston flow at outlet of extruder place change into more, played main effect near the pattern of laminar flow.

Do not consider potential reason, find that method and apparatus as herein described can reduce or eliminate basically the squeeze-up face crack effectively.Pottery through some step improvement plasticising forms mixture of powders flowing from outlet of extruder towards die head; Realized these results, realized these improvement in the following manner: improved the structure that is used for the conduit that outlet of extruder and extrusion die inlet is continuous or is connected shell is provided usually.

Although do not hope the purposes of method and apparatus of the present invention is not limited; But method and apparatus of the present invention is particularly suitable for making the large size ceramic honeycomb body structure; Honeycomb ceramics squeeze-up size or surpass 25 centimetres with the diameter of the cross section of the axle traversed by of carrying the material through equipment for example, perhaps area is above 750 centimetres ²The above-described frequency of occurrences that radially ftractures problem is higher than the frequency that occurs in the less honeycomb ceramics formed body of preparation in preparing such structure.

Fig. 1 has shown the cross section front elevational schematic that is fit to make according to method of the present invention the equipment of large-scale and small-sized honeycomb body.Equipment 10 comprises extruder 12, honeycomb ceramics extrusion die section 14, and be connected shell 16 with what extruder 10 and die head 14 linked to each other.Through two extruder screws 18 the pottery formation mixture of powders (not shown) of plasticising is mixed, and 14 conveyings from extruder 12 towards honeycomb ceramics extrusion die section.The function of said connection shell 16 is as passage, and the mixture of plasticising is formed, and is used for carrying towards die head section 14.Although be shown as independently mechanical organ among Fig. 1, the present invention also can adopt other equipment configuration, and in said other equipment configuration, shell 16 is as the extension of extruder 12 or die head section 14, and is perhaps integrated with them.Method and apparatus of the present invention comprises that pottery forms the plasticising mixt of material, can apply active force through single screw rod or double screw extruder or plunger-type extruder and force these materials through said shell.

The known connection shell that in the equipment of setting mentioned above, uses has constituted the difficult point at the plasticity squeeze-up perimeter flow velocity that is obtained by die head.Known shell is formed by withstand voltage, the high-abrasive material of steel and so on usually; We find that these materials can be to the very big resistance of mobile generation of mobile mixture peripheral part, and these resistances are because the friction interaction between steel surface and the plasticising mixt causes.Therefore, it is faster than perimeter that the pottery of plasticising forms the translational speed of mixture flowable materials center, is equivalent at place, die head neighboring area, and mixture lacks enough flowing.

Periphery flows slowly, particularly under slow rate of extrusion condition and/or extrude in the large diameter part process that periphery slowly flows seemingly because cause in " dead band " in the peripheral flow stream, or even the obstruction of die head marginal portion.The mobile generation ring tension of central part material faster shows as and produces the radial surface crackle then.Particularly for bigger honeycomb ceramics, discovery can form the crackle that extends to the broad of crust lower curtate from the crust of honeycomb ceramics squeeze-up.

In equipment as herein described and method, the inner surface that the mixing of said extruder/transmission screw element and being used for forms mixture on the connection shell between the die head section of honeycomb ceramics squeeze-up is " reducing friction ".Owing to can reduce friction, increased and be transmitted the flowable materials that the pottery that is transported to the plasticising of die head through shell forms material and flow at the material of peripheral part.

Through with next person or the combination of the two, realized the interactional minimizing of friction between plasticising mixt and the inner surface of outer cover: (i) change the material that is used for forming inner surface of outer cover; (ii) change the surface profile of these surface portions.The inner surface of shell is represented to form the whole surface that mixture contact with the pottery of plasticising, and perhaps inner surface part still less is as long as be enough to the improvement that realizes that desired periphery is mobile on the area.

Can realize forming the variation of the material of inner surface through the applicator surface layer, the composition of the material of said superficial layer is different from the main body or the composition below the surface of said shell, and its coefficient of friction is less than the coefficient of friction below the surface.Its example comprises the durability polymer surfaces that is provided by coating wear-resisting, that low friction property polymeric material forms or lining.The way that the surface profile of inner surface is changed to reduce mantle friction comprises: on said surface, form texture through impression or other method, said texture can reduce the net area that contacts between said mobile plastic mixture and the inner surface of outer cover.

Fig. 2 demonstration can be used for the cross section of an embodiment of connection shell of method of the present invention and face enlarged diagram.In this specific embodiment, simultaneously the material composition of inner surface of outer cover and the texture or the surface profile on surface are changed.

Fig. 2 more specifically below, shell 16 comprises external shell 20 and interior lining 22, and said external shell 20 is formed by the high-tensile material of for example steel and so on, and said interior lining 22 is formed by for example ultra-high molecular weight polyethylene (UHMWPE) polymer.The required characteristic of case surface shown in Figure 2 comprises low-friction coefficient and good wearability, and this is to be exactly abrasive material because form mixture of powders itself according to the pottery of the plasticising of these methods processing.Can also use other low frictional properties polymer, fluorocarbon polymer for example, even the inorganic surfaces material of reducing friction, for example nickel or tungsten carbide.Same, although in the embodiment of Fig. 2, interior lining covers the inner surface that connects shell fully, only on this surperficial some parts, provides the embodiment on the surface that reduces to rub also effective result can be provided.

Another characteristic of shell shown in Figure 2 is the surface 24 that on lining 22, impresses out veining.In the specific embodiment that shows in the drawings, the surface 24 of veining comprises continuous ditch 26, and these ditches 26 are with respect to the direction orientation of the arrow 28 that passes through shell 22 intermediate openings with traversed by.Arrow 28 is extruded axle corresponding to honeycomb ceramics, or the pottery of plasticising is formed mixture 30 transmission through connecting the direction that shell 16 is transported to the extrusion die section, shows among the figure.

Ditch 26 among Fig. 2 can provide with the form of a series of annular ditch of surface in 24, perhaps can be to extend to the independent scroll ditch that the traversed by of outlet should the surface from the inlet of lining 22 in the enclosure.In some embodiments, the annular in the lining 22 and the orientation of scroll ditch all are roughly circumferencial direction, and the material throughput direction (28) among this circumferencial direction and Fig. 2 is traversed by substantially.The angle that the cardinal principle traversed by is represented ditch alignment direction and material throughput direction is greater than 45 °.

Although the specific embodiment shown in Figure 2 is a texturizing surfaces, like surface 24, it comprises surperficial ditch, also can adopt other texturizing surfaces, and its example comprises the surface of corrugated and the surface that comprises the depression of depression and flute profile formula.Without wanting to be limited by theory, think that the modes such as contact area that the surface of these veinings can form between mixture and the case surface 16 through the pottery that for example reduces said plasticising reduce friction.

Fig. 3 a-3c provides the schematic cross-section that is fit to be used for improve the polymer linner that connects shell, can be used as the lining case surface of veining in conjunction with the lining on the surface with ditch, is used in method of the present invention, reducing friction.Fig. 3 a has shown a sectional view 22a who combines the polymer linner of texturizing surfaces 24a; Wherein the surperficial 24a of veining has combined the zastrugi shape thing of sinusoidal configuration or wave structure; And the sectional view 22b of Fig. 3 b comprises the surperficial 24b of the ditch that has combined laciniation, and the sectional view 22c of Fig. 3 c comprises the surperficial 24c with brachymemma laciniation.

Some textural characteristics; For example the suitable dimensions of the ditch shown in Fig. 3 a-3c depends on that polymer inserts the concrete composition and the character of body; Depend on that also the pottery of the plasticising of processing forms the character of mixture, but can confirm at an easy rate through normal experiment.For example, for the UHMWPE lining of kind mentioned above, the degree of depth of ditch and the spacing of ditch all preferably are about the 0.3-0.7 millimeter.

As indicated above, can produce the other effect of reducing friction through the interaction between texturizing surfaces and the plasticising mixt that for example uses at present in the ceramic honeycomb body manufacturing.These mixtures can combine the liquid mediums component of most inorganic component (for example powder) and few part, and component medium often comprises one or more lubricants.Therefore the depression in the said texturizing surfaces can be used as the storage of lubricating fluid component medium (for example oil component), forms the mixture from the horizontal pottery of the plasticising of flowing through said connector and collects oil component.As substituting or adding, said depression can be used as the storage of plasticising mixt itself.Under any situation; Logistics through the connector contact surface becomes " stream of batching on batching "; " batching on oil stream ", perhaps " batching on the oil stream on batching " again significantly reduces the tight exposure level between the actual inner surface of mixture and connector.

Do not consider the mechanism that under observed function, comprises; Low friction of the present invention and/or texturizing surfaces (no matter in the hub plate or other forms provide) all have and promote or improve the clean effect that periphery flows with other mode; Make that the flow profile of the squeeze-up that flows out from the die head section as indicated above is more even, and squeeze-up keeps having basically no radial cracking and other forms of deformation.

As indicated above; The embodiment of methods described herein comprises certain methods; The inner surface of wherein the reducing friction surface that included go up to limit a plurality of protrusions of a large amount of grooves, comprises that wherein groove forms ditch in inner surface and said ridge is the embodiment of the form of ridge.Object lesson with embodiment of a plurality of protrusions comprises following embodiment: wherein the height of protrusion is the 0.005-0.050 inch.The example that in inner surface, has the said method of ditch comprises following embodiment: wherein combined annular or spiral ditch.

Wherein protrusion is that the embodiment of ridge comprises following situation: ridge is the 0.005-0.050 inch at interval, perhaps 0.010-0.040 inch at interval.Also comprise some embodiments, wherein each ridge is made up of corresponding paired inclined wall, and said paired inclined wall stops at corresponding top.The example of a kind of embodiment in back comprises following situation: the paired inclined wall of at least a portion ridge forms the angle of 50-70 degree each other.Comprise in the embodiment of inclined wall that at these corresponding top can be pinnacle, flat-top or dome.

In some embodiments of the above method; Protrusion in the inner surface of reducing friction is the form of ridge, the distance between the height of the hydraulic diameter adjusting ridge of the cavity that can limit according to the inner surface of reducing friction tube-like envelope and/or the ridge.In the embodiment of said method, said hydraulic diameter is 200-1000 divided by the ratio apart from gained between two adjacent ridge.In certain methods, hydraulic diameter is 200-2000 divided by the ratio of ridge height gained, for example is 200-1200 in addition.

The present invention also provides some to form the method for honeycomb ceramics squeeze-up; Wherein squeeze-up has at least a in the following characteristic: (i) surpass 25 centimetres with the cross sectional dimensions of extruding the direction traversed by, perhaps (ii) with the cross-sectional area of extruding the direction traversed by above 750 centimetres ²These methods provide the honeycomb ceramics squeeze-up with big cross-sectional area as herein described; This honeycomb ceramics squeeze-up does not have the radial surface crackle basically; Can comprise some embodiments; Wherein squeeze-up comprises the pottery formation mixture of plasticising, and the pottery of said plasticising forms the liquid mediums component that mixture has combined most inorganic component and few part, and said liquid mediums component comprises at least a lubricant.

The method that is used for forming the honeycomb ceramics squeeze-up as herein described comprises some embodiments; The wherein said inner surface that reduces to rub is a texturizing surfaces; The surface that for example combines one or more surperficial ditches, the ditch of said surperficial ditch orientation form mixture of powders with the pottery of said plasticising substantially and extrude direction or transmission axle traversed by through shell.The example of said surperficial ditch is the ditch that forms corrugated or zigzag inner surface.

The advantage of method and apparatus as herein described is not limited only to surperficial integration mentioned above and improves.Through using equipment as herein described and method; Can be to more the plasticized ceramic formation mixture of powders composition and the character of wide region are extruded; Said extruding can be carried out under the extruded velocity of wide region more and squeeze-up size, for example successfully is used for flawless honeycomb ceramics and extrudes.

Carried out above description although combined the specific embodiment of method and apparatus as herein described; But be to be understood that these embodiments are only used for illustrating; Can under the situation that does not deviate from the appended claims scope, adopt other embodiment at an easy rate for concrete purpose.

Claims

1. the method for main body is extruded in a formation, and it comprises:

Force pottery to form material along extruding direction through tube-like envelope and through extrusion die through applying active force, said tube-like envelope comprises the inner surface of reducing friction.

2. the method for claim 1 is characterized in that, said inner surface of reducing friction comprises a plurality of protrusions, and said protrusion limits a plurality of grooves on said inner surface.

3. method as claimed in claim 2 is characterized in that said protrusion is a ridge, and their each free corresponding inclined walls are in pairs formed, and said paired inclined wall stops at corresponding top.

4. method as claimed in claim 3 is characterized in that, said ridge is along being orientated with the direction of extruding the direction traversed by substantially.

5. method as claimed in claim 3 is characterized in that, said ridge is annular or scroll.

6. method as claimed in claim 3 is characterized in that, said flute profile grooving.

7. method as claimed in claim 6 is characterized in that, said ditch is annular or scroll.

8. method as claimed in claim 3 is characterized in that, said inner surface of reducing friction limits the internal cavities with hydraulic diameter.

9. method as claimed in claim 8 is characterized in that, said hydraulic diameter is 200-1000 divided by the ratio apart from gained between two adjacent ridge.

10. the method for claim 1 is characterized in that, said inner surface of reducing friction is made up of following material: ultra-high molecular weight polyethylene (UHMWPE) polymer, fluorocarbon polymer or nickel or tungsten carbide, perhaps their combination.

11. the method for claim 1 is characterized in that, applies active force and forces said pottery to form material through single screw extrusion machine, double screw extruder or plunger-type extruder.

12. the method for claim 1 is characterized in that, said extrusion die is configured to be used for forming the main body of extruding with honeycomb body structure.

13. the pottery by plasticising forms the equipment that mixture is made the honeycomb ceramics squeeze-up, said equipment comprises: (i) extruder; (ii) honeycomb ceramics extrusion die; And the (iii) connection shell between said extruder and extrusion die, said shell is used for the mixture of plasticising is transferred to said die head from said extruder, and said connection shell combines with the inner surface of reducing friction.

14. equipment as claimed in claim 13 is characterized in that, said inner surface of reducing friction comprises the superficial layer of solid material, and the composition of said solid material is different from the composition of said case surface below.

15. equipment as claimed in claim 14 is characterized in that, said superficial layer is the lining that is formed by wear-resisting low friction property polymeric material, and the coefficient of friction of said polymeric material is lower than the coefficient of friction of lower face.

16. equipment as claimed in claim 13 is characterized in that, said inner surface of reducing friction is the surface of veining.

17. equipment as claimed in claim 16 is characterized in that, the surface of said veining combines with one or more surperficial ditches, and the ditch orientation of said surperficial ditch is cardinal principle and the mobile direction of passing through the transmission axle traversed by of shell of the mixture of said plasticising.

18. equipment as claimed in claim 17 is characterized in that, said inner surface of reducing friction limits the internal cavities with hydraulic diameter, and said hydraulic diameter is 200-1000 divided by the ratio apart from gained between two surperficial ditches.

19. equipment as claimed in claim 13 is characterized in that, the cross sectional dimensions of the transmission axle traversed by of the powder mixes flow of at least one of said connection shell and said plasticising through shell is above 25 centimetres.

20. equipment as claimed in claim 13 is characterized in that, said extruder is single screw extrusion machine, double screw extruder or plunger-type extruder.