CA1203061A - Masking apparatus for selectively charging honeycomb structures - Google Patents

Abstract

ABSTRACT

Improved masking apparatus and methods for bulk charging a flowable material into selected cell ends exposed at an end face of a honeycomb structure. The masking apparatus utilize protrusions which assist in properly aligning the apparatus to the end face and reduce the possibility of improperly charging cells. In one apparatus embodiment, a planar body is provided having a plurality of hollow protrusions which extend into selected cell ends when the planar body is fitted against an end face of the structure. A flowable material charged against the planar body passes through the hollow protrusions into the selected cell ends. In another embodiment, a plurality of preformed protrusions or plugs are mounted along thin, flexible members at predetermined locations. The plugs are inserted into and block or cover the ends of an equal plurality of cells. A flowable material charged against the end face passes into the remaining, uncovered cells.
The invention is of particular use in fabricating solid particulate filter bodies from ceramic-based honeycomb structures.
Preferably the mask is made of a flexible material, for instance a polymer, preferably an elastomer. Also described are apparatus and dies for making the die.
Furthermore, a method of aligning the flexible mask with a honeycomb body by vibration is described.

Description

BACKGROUND OF THE INVENTION
This invention relates to charging flowable materials into selected cells of a honeycomb structure and, more particularly, to methods and related apparatus for selectively manifolding (i.e. plugging) cells of a honey-comb structure for the fabrication of filter bodies and other selectively sealed honeycomb structures.
Honeycomb structures having transverse, cross~
sectional cellular d~nsities of one-tenth to onehundred or more cells per square centimeter, especially when formed from ceramic materials, have several uses, such as solid particulate filter bodies and stationary heat exchangers, which may require selected cells of the structure to be closed or blocked by manifolding or other means at one or both of their ends.
A solid particulate filter body may be fabricated utilizing a honeycomb structure having a matrix of intersecting, thin, porous walls which extend across and between two of its opposing open end faces and form a large number of adjoining hollow passages or cells which also extend between and are open at the end faces. To form a filter, one end of each of the cells is closed, a first subset of cells being closed at one end face and the remaining cells at the remaining end face, so that either may be used as the inlet or outlet end of the filter. A
contaminated fluid is broughtunder pressure to one face (i.e. the "inlet" face) and enters the filter bodies via the cells which are open at the inlet face (i.eO the "inlet" cells). Because the inlet cells are sealed at the remaining (i.e. "outlet") end face of the body, the cont~min~ted fluid is forced through the thin, porous walls into adjoining cells which are sealed at the inlet face and open at the opposing "outlet" end face of the filter body (i.e. "outlet" cells). The solid particulate contaminant in the fluid which is too large to pass through 3~

the porous openings in the walls is left behind and cleansed fluid exits the outlet face of the filter body through the outlet cells for use~
Parallel work by applicant, as disclosed in the European application issued under No. 81302986.5, has resulted in a most efficient solid particulate filter body formed from a honeycomb structure in which the cells are provided in transvexse, cross-sectional densities between approximately one and one hundred cells per square centi-meter with transverse, cross-sectional geometries having no internal angles less than thirty degre~s, such as squares, rectangles, equilateral and certain other triangles, circl~s, certain elipses, etc. The cells are also arranged in mutually parallel rows and/or columns.
Alternate cells at one end face are filled in a checkered or checkerboard pattern and the remaining alternate cells are filled at the remaining end face of the structure in a reversed pattern. Thus formed, either end face of the filter body may be used as its inlet or outlet face and each inlet cell shares common walls with only adjoining outlet cells, and vice versa. Other cellular cross-sectional geometries and other patterns of sealed cells may be employed to fabricate effective, although perhaps less efficient filter bodies than those disclosed by the a~oresaid applicat~on.
For the mass production of such filters, it is highly desirable to be able to block selected cell ends as rapidly and as inexpensively as possible. The previously referred to European application No. 81302986~5 describes fabricating filter bodies by plugging the end of each cell individually with a hand-held, single nozzle, air actuated sealing gun. The hand plugging of individual cells by this process is long and tedious and is not suited for the commercial production of such filters which may have ~2~3~

thousands of cells to be selectively sealed. European application No. 81302986~5 also postulates the use of a sealing gun mounting an array of sealant nozzles so that the plugging mixture may be simultaneously înjected into a plurality or all of the alternate cells at each end face of the honeycomb structure. However, a working model of this device is not known to exist for plugging honeycomb structures having the higher cell densities referred to.
An alternative approach to manifolding selected cells at an end face of a honeycomb structure has been developed by the applicant, in which an open surface of a honeycomb structure is covered by a mask having a number of openings extending through it. Plugging material is charged against the outer surface of the mask and through its openings into the proximal open ends of cells opposite the openings. A rigid plate having a plurality of bores extending through it which are spaced and sized ~o coincide with the open ends of the selected cells at the end face of a honeycomb structure when the plate is positioned against the end face in alignment with its bores opposite the selected cells is used. Successful use of such an apparatus is dependent upon the ability to provide honey-comb structures having end faces conforming to the face o~ the masking apparatus so as to prevent gaps therebetween which would allow the sealing material to charge into adjoining cells and to provide predetermined, undistorted positioning of the cells at the end face of the honeycomb structure for accurate registration of the selected cells with the openings in the mask, again, to prevent possible charging of sealing material into adjoining cells.
In a related areal U.S. Patent 4,410,591 describes alternate methods o~ fabricating a multiple flow path body such as a stationary heat exchanger in which a honeycomb structure is provided having its cells arranged in columns across its open end faces, an open end face of a honeycomb structure is dipped into a flowable resist material and 3~

the resist material remDved from selec~ed columns by cutting it away together with the common walls of the adjoining cells in the ~elected column or~ alternatively,~he wallsbetween the adjoining cells of the selected columns are cut away at the open end face of the structure before dipping the end face into the flowable resist material, then the resist material is blown from the selected columns using compressed air directed down the selected columns where the adjoining cell walls have been removed. The end face was therea~ter dipped into a slurry of cement to form a sealed channel across each o~ the selected columns. The remaining flowable resist material was subsequently removed by heating.
Although these methods do not involve charging a permanent plugging material into cells as the purpose is to create channels across the ends of cells, sufficient plugging material could be provided to block the cell e~ds exposed by the cutting step. As the cross-sectional density of cells in the honeycomb structure is increased, for example to improve the efficiency of a filter body, the tolerances needed ~or the removal of adjoining cell walls required by these methods tigh~en. The problem is particularly heightened when the filter bodies are fabricated from extruded ceramic or ceramic-based honey~
comb structures as the present state of the ceramic extrusion art cannot provide perectly parallel rows and/
or columns of cells. Also, these methods requir~ the partial destruction of adjoining cell walls and are entirely unsui~ed for the fabrication of filter bodies or other selectively sealed honeycomb structures where the cells are plugged in a checkered or other possible alternating cell patterns at the end faces.

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SUMMARY OF THE INVENTION
The invention relates to a mask or use in bulk charging a flowable material into a selected subset of cells of a honeycomb structure having a pair of opposing end faces and a matrix of thin walls defining a multiplicity o~ hollow, open ended cells extending through said s~ructure between said pair of end faces~ said mask apparatus comprlslng:
at least one base member adopted to be positioned across one end face, a plurality of protruding members extending Erom each base member in the s~ne direction and in special and shaped arrangement that permits each protruding member to register with, be inserted in an open end of one of said cells, and means at said one end ~ace for providing open access to open ends of cells in said selected subset by said flowab].e material~
The invention further relates to a method of bulk charging a flowable material into a selected subset of cells of a honeycomb structure having a pair o~ opposing end faces and a matrix of thin walls defining a multiplicity of hollow open ended cells extending through said structure between said pair of end faces, comprising the steps of providing a mask apparatus, applying s~id mask apparatus to an end face and charging said flowable material against and through said mask apparatus and into said selected subset of cells, the improvement comprising the steps of.
providing the mask described above and during said applying step, inserting said each protruding member into an open end of one of said cells.

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It is an object of the invention to provide a method for selectively bulk charging cells of a honeycomb structure with a flowable material which is compatible with any desired pattern of cells selected to be charged.
It is yet another obj~ct of the invention to minimize the overspill of sealing material when bulk charging selected cells of a honeycomb structure.
It is yet another object of the invention to provide a method of selectively manifolding large numbers of cells of honeycomb structures that is more rapid and less expen.sive than hand filling individual cell ends.
The invention further relates to a method of fitting a first member having a plurality of protrusions extending therefrom to a second member having a honeycomb surface with a multiplicityof openings extending therethrough, said protrusions engaging selected ones of said openings when said first member is fitted to said second member, comprising the steps of:
positioning said first member and said protrusions against said surface; and vibrating at least one member until said protrusions engage said selected openings.
In another embodiment, the invention relates to a method of fabr.icating a solid particulate filtered body ~omprising the steps of:
2S providing a honeycomb structure having a multiPlicity oE hollow cells extending through the structure and through a pair of end faces of the structure, said end faces being substantially identical and formed by a matrix o:E porous intersecting walls also extending therebetween and therethrough;
providing a pair of masks, each mask haviny a pair of opposing faces, a plurality of openings extending between and through said opposing faces and a plurality of protrusions extending from one opposing face;
approximately centering one mask with one ~Za;~3(~

6a end face; and vibrating said one mask int~ alignment against said o~e end face with its opeings exposing a first subset of cells and its plurality of protrusions engaging an equal plurality of the remaining cells.
The invention further relates to a combination comprising:
a honeycomb structure having a pair of opposing end faces and a multiplicity of cells formed by thin walls extending through and between said end faces;
a body having a plurality of protrusions extending therefrom, and being positioned with its protrusions against one end face of said honeycomb structure;
means for limiting lateral motion of said body acxoss 'said end face; and means for vibrating said body with respect to said one end face.
Further objects and advantages of the invention will become apparent as the description thereof proceeds.
A summary of the invention and its various ~sp~cts will be found in the appended claims.
D~SCRIPTION OF THE DRAWINGS
The various aspects of the invention are better understood with reference to the accompanying drawings, in which:
Figs. l and la depict a solid particulate filter body fabricated using the inventive methods and apparatus;
Fig. 2 depicts a honeycomb structure and first mask embodiment;
Fig. 3 depicts in a sectionedl profile view~
the mask embodiment of Fig. 2 fitted to the honeycomb structure;
Fig. 4 depicts a flowable material being charged through one of the hollow protrusions of the mask embodiment of Figs. 2 and 3 into a cell of tha honeycomb structure;

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6b Fig. 5 depicts a press apparatus for using the several mask embodiments of ~igs. 2 through 4 and 6 through 7b;
Fig. 6 d~picts a second mask embodiment of the invention being fitted to an end fac~ of a honeycomb;
Fig. 6a depicts a thin flexible member and pre~ormed plugs of Fig. 6 in an expanded view;

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Fig. 6b is an expanded, sectionea, view of area 6b of Fig. 6 depicting the covering of the open ends of some of the cells by individual plug members and their protrusion into the cell ends;
Fig. 6c is an expanded end view of the area 6c of Fig. 6 showing the arrangement of plug elements in alternate cells of the honeycomb structure exposing the remaining cells in a checkered pattern for filling;
Fig. 7 depicts a preferred embodiment of the invention, an elastic mask, and a honeycomb structure with which it is used;
Fig. 7a is a view of the downstream face of the mask embodiment of Fig. 7 along the lines 7a 7a depicting the relative positioning of some of its protrusions and lS openings;
Fig. 7b is a cross~sectional profile view along lines 7b-7b of Figure 7;
Fig. 8 is a perspective, schematic view of the subject flexible mask and a honeycomb structure with which it is used;
Fig. ~ is an end face schematic view of the subject flexible mask of Fig. 1 showing the relative positioning of some of its adjoining openings and protrusions;
Fig. 10 is a sectioned view of the subject flexible mask being fitted to an end face of the honeycomb structure;
Fig. 11 is a greatly expanded and sectioned schematic view of the mask fitted to the end face o-f the honeycomb structure;
Fig. 12 is a schematic view of a solid particulate filter body formed using the mask and honeycomb structure of Figs. 1 through 4;
Fig. 12a is a sectioned view of the filtex body of Fig. 12 along lines 12a-12a;

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Fig. 13a is a sectioned schematic view of a simple die for casting a flexible mask having protrusions but no openings;
Fig. 13b is a sectioned schematic view of the mask formed on the simple die depicted in Fig. 13a having openings being formed through it;
Fig. 14a is a sectioned schematic view of a second simple die for forming a flexible mask having both protrusions and openings, showing a polymer being loaded into the die;
Fig. 14b depicts the upper surface of the polymer cast into the second simple die of Fig. 14a being smoothed to form an outer surface of a flexible mask;
Fig. 14c depicts schematically the curing of the mask in the second simple die in an oven;
Fig. 14d depicts schematically the flashing being removed from the lower outer surface of the second simple die after the mask has been cured;
Fig. 14e depicts a sectioned, schematic, profile view of the mask produced in the second simple die by the steps depicted în Figs~ 14a through 14d;
Fig. 14f depicts schematically the undersizing of the mask with respect to the cells of the honeycomb structure;
Fig. 15a is an exploded schematic view of a compound mask forming die appartus;
Fig. l5b is a sectioned profile view of the compound die apparatus of Fig. 15a in an assembled form;
Fig ~ 16 is a sectioned t schematic view of a press apparatus for charging a p]astically formable material such as a plugging cement into a honeycomb structure using the subject flexible mask; and Fig. 17 is a schematic sectioned view of a envisioned press apparatus having a subject flexible mask incorporated into its exit orifice.

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Fig. 1~ is a schematic view of apparatus for aligning a mask having protrusions to an end face of a honeycomb structure;
Fig 19 is a cross-sectional view of the mask fitted to the end face o the honeycomb structure of Fig. 18;
Fig. 20 is a schematic view of a preferred filter body fabricated with the mask and honeycomb structure of Figs. 18 and 19;
Fig. 21 is a cross-sectional view of the filter body of Fig. 20 along the lines 21-21 showing the pattern of cells being plugged at alternate ends;
Fig. 22 depicts patterns of openings and protrusion locations for the central portions of reverse masks centered over a cell on the end faces of a honeycomb structure;
Fig. 23 depicts a view of the central portion o an end face and the two subsets of cells which are exposed using identical masks centered on the end face at one of two locations over a thin wall forming the cells;
Fig. 24 is an exploded view of the central portion of identical masks showing the two corresponding locations of their axial centers used with each of the two axial center locations of the end face represented in ~ig. 23;
Figs.25 through 27 depict various embodiments using rigid members extending between a mask and end face to restrict theix relative lateral or lateral and angulax movement during the step of vibrating the mask into alignment.
DETAILED DESCRIPTION OF THE lNV~ ON
A preerred use of each o the embodiments of the present invention is the fabrication of solid parti-culate filter bodies as described in ~he aforesaid European application No. 81302986.5. An exemplary preferred filter body of that invention i5 depicted in Fig. 1 and 3~

in a cross-sectioned ~iew along the line la-la in Fig. la.
The filter body comprises a honeycomb structure 10 ha~ing a multiplicity of hollow, open ended passages or cells 11 which typically extend in an essentially mutually parallel fashion through the structure 10 so as to reduce back pressure in the filter body being fabricated. The ends of the cells 11 are open at and form a pair of substantially identical open outer surfaces at end faces 12 and 13 of the structure. The cells 11 are themselves formed by a matrix of intersecting walls 14 which extend between each of the end faces 12 and 13. For ~ilter body applica~ions, the walls 14 are porous and continuous across the end faces 12 and 13 and prefera~ly uniformly thin, although walls of non-uniform thickness may be used with less efficiency. A thicker, outex "skin" 15 may be provided around the cells 11 and thin walls 14 between the end faces 12 and 13.
Honeycomb structures or solid particulate filtering and other applications may be formed from a variety of porous materials including ceramics, glass-ceramics, glasses, metals, cermets, resins or organic polymers, papers, or textile fahrics (with or without fillers, etc.), and various combinations thereof and by a ~ariety of methods depending upon the material(s) selected. Honeycomb structures having the necessary uniformly thin, porous and interconnacted walls for solid particulate filtering applications are preferably fabricated from plastically formable and sinterable, finely div-ded particles and/or short length fibers of substances that yield a porous, sintered material after being fired to afect their sintering, especially metallic powders, ceramics, glass-ceramics, cermets~ and other ceramic-based mixtures~ An extruded ceramic honeycomb structure having cordierite as its primary crystal phase, whi.ch is preferred for moderately high temperature solid ~IZ63 3~

particulate filtering applications (1,000 centigrade or more) due to its low thermal expansion characteristics, may be provided in the manner described in the afore-mentioned European application No. 81302986.5. Several exemplary raw material mixtures are described therein which yield honeycomb structures with ~hin walls having various open porosities. The filter body is formed by plugging, covering or otherwise blocking the ends of a subset of alternative cells at one end face of the structure and the rema~ining cells at the remaining ~nd face of the structure. In Figs. 1 and la, alternate cells 11 of the honeycomb structure 10 have been blocked with plugs 16 at either end face in a checked or checkerboard pattern described and claimed in the aforesaid European application No. 81302986.5. The plugging pattern on the end face 13 (hidden in Fig. 1) is the reverse of that depicted on the end face 12. Further inoxmation regarding the use and operation of the described filter bodies is provided in the aforesaid ~uropean application No. 81302986.5.
The plugs 16 are selected from a material compatible with the composition of the honeycomb structure and its ultimate use as a filter bodyO Where the aforesaid cordierite structures are used for filtering applications, cordierite cement plugs 16 are preferably provided or compatibility. Suitable foaming cordierite cements are described and claimed in a copending Canadian application Serial No. 380,875 filed June 30, 1931 and entitled PATICULATE FILTER AND MATERIAL FOR PRODUCING THE SAME, which is assigned to the assignee of this application.
A particular composition of the cement preferred for high sodium ion exhaust gas filtering applica~ions is provided in the aforesaid European application No. 81302986.50 Nonfoaming cordierite cement compositions may be used with the porous walled cordierite substrates identified in the aforesaid European Patent No. 81302g86.5. Alter-natively, other ceramic cements and other plugging ~3~

materials may be used with cordierite or other honeycomb structures to fabricate filter bodies and other selectively plugged honeycomb structures using the subject invention which is hereinafter described in three embodiments, including a preferred embodiment, in the context of fabricating the described solid particulate filter bodies.
Fig. 2 depicts a honeycomb structure 10 again having cells 11 formed by thin walls 14 extending between end faces 12 and 13 with a first embod~ment mask 20 of the subject invention. The mask 20 comprises a rigid, essentially plate-like body 21 having opposing upstream and downstream faces 22 and 23. The body 21 has a plurality of bores 21a extending axially between its surfaces 22 and 23 each of which is fitted with a hollow tube 24 which protrudes like a nipple from the downstream surface 23 of the mask body 21. The mask 20 is used by positioning its downstream face 23 against an end face 12 (or 13) of the structure 10 as indicated by the arrows 25, preerably until the down-stream surface 23 is substantially flush with the end face 12 (or 13) as is depicted in Fig. 3. The tubes 24 are positioned with respect to one another a_ross the mask body 21 and sized so as to coincide with and extend into the ends of selected cells when the mask 20 is fitted to the end face 12 (or 13~ of the structure 10. A suitably flowabl~ material (indicated by shading in Fig. 4), such as one of the aforesaid ceramic plugging cements, which is charged against the upstream face 22 of the mask 20 under pressure passes through the tubes 24, as is indicated by the arrows 26 in Fig. 4, into the ends of the selected cells into which each tube 24 extends. Desirably, the outer surface of protruding nipples of tubes 24 taper inwardly as they extend from the plate-like body 21 so as to present a smaller transverse cross-sectional area at their tip for easier registration with the open cell ends.

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The base of the nipples may be sufficiently wide so as to rest on or fit snugly into the ends of the selected cells 11 to prevenk the flowable plugging material from spilling or oozing over into adjacent cells which are to remain open or unplugged. The mask 20 may be made from metal components by assembly, in the manner described, or monolithically by such methods as casting, or altexnatively, from other formable or machinable rigid materials. It is also envisioned that the mask may be formed monolithically from a flexible or elastic polymer material in a manner similar to the preferred embodiment subsequently described herein.
Fig. 5 depicts an exemplary press apparatus 30 which may be used with the first embodiment mask 20 to charge a plastically formable cement or other viscous material into selected cell ends o a honeycomb structure.
The apparatus 30 comprises a press head 31 housing a pis~on 32 traveling in a bore 33 which is open at an outer surface 31a of the head 31 and additional frame members 34 supporting a hand-operated screw 35 or other suitable means for moving the piston 32 in the bore 33. A honeycomb structure 10 is charged using the mask embodiment 20 and the subject press apparatus 30 by withdrawing the piston 32 into the chamber 33 forming a cavity between its head 32a and the outer surface 31a of ~he press head 31. The ceramic cement or other material to be charged in~o the structure 10 is loaded into the cavity. The honeycomb structure 10 with fitted mask 20 is applied o~er the bore 33 and against the surface 31a of the press head. Th~
structure 10 and mask 20 are held in position by suitabl~
means such as a bar 36 positioned over the opposing end face 13 of the structure, which bar is held in position by suitable means such a threaded bolts 37 extending into suitably threaded bores 38 in the press head 31. The piston 32 is then advanced towards the mask 20 by means of the 3~

screw 35 and presses the material in the cavity through the tubes 24 into the proximal ends of the cells 11 forming plugs 16. Plugs 16a have been f~rmed in the rPm~;n;ng alternate calls of the s~ructure 10 at the opposite end face 13 in a similar, previous filling operation. The structure 10 is then removed from the press head and the plugs 16 and 16a fixed in position by sintering in the case of the aoresaid cordierite cements or by drying, curing or other appropriate steps for other plugging materials.
Figs. 6 through 6c depict a second embodiment of the inven~ion, a multiplicity of preformed plug elements each of which is inserted into and blocks or covers the open end of a cell 11 at an end face 12 (or 13) of a honeycomb structure 10. For convenience, the plugging elements 40 are preferably prepositioned along elongated members 41 such as 1exible wires, which are sufficiently thin ~i.e. of width perpendicular to members 40 smaller than width of cells) so as to not overlap or substantially block cells ad~oining those ~emporarily plugged with the members 40. The flexible members 41 assist considerably the use of the plug elements 40. The flexibility of the ; members 41 allows some latitude in aligning the plug elements 4n with distorted arrangements of cells at an end face. The members 41 also locate the plug elements 40 in the vicinity of the appropriate cell ends during inser-tion and provide a means for quickly removing the plugs after the selected cells o the structure have been charged. Each element 40 has a central body portion 4Oa which is sufficiently small in diameter so as to be 3Q inserted into an open end of a cell 11. Additionally, each plug element 40 is provided with a larger head portion 40b having a diameter greater than the minimum diameter or width of the open, transverse, cross sectional areas of the cells. Head portion 40b both covers the cell ends preventing their charging and prevents the plugs 40 ~rom being pushPd complet~ly past the end face into a cell end during the charging process. To plug alternate cells 11 arranged in rows and columns at an end face 12 of a honeycomb structure in the aforementioned checkered or checkerboard pattern, flexible elements 41 each carrying oneor more plug elements 40 are arranged along alter~ate, paxallel diagonals of cells at an end ace, as indicated in Fig. 6c. The plug elements 40 may be inserted into the cells along the remaining alternate diagonals at the opposing end face of the structure 10 to achieve the desired, reversed, checkered or checkerboard plugging pattern. The flexible members 41 may be provided sufficiently long so as to o~erlap the sidewalls 14 of the structure 10 where they may be held in place by suitable means 42 for the charging methods selected~ For example, the press apparatus 30 of Fig. 5 may be used by stretch-fitting an oversized collar, such as an annular, hollow neoprene ring having an inner circumference sli~htly less than the outer circumference of the end ace 12, over the end face 12 and onto the structure sidewalls 15 and ends of the flexible members 41. Alternatively, an adjustable clamp, tape or other means may be used to secure the ends of the flexible members 41 to the sides 15 of the structure 10. A working model of the masking apparatus depicted was fabricated by soldering small, copper rivets at predetermined locations along thin, copper wires.
Although the depicted arrangement of the flexible members 41 along diagonals of cells arranged in rows and columns is preferred for the fabrication of solid particulate filter bodies having the preferred checked plugging pattern depicted in Fig. 1, it is envisioned that other plugging patterns can be achieved by other spacings of the plugging elements 40 along the flexible members 41 and other orientations of the members 41 across an open end ~ace of a honeycomb structure 10.
~n embodiment of the invention which is preferred for fabricating solid particulate filter bodies or for otherwise charging 10wable materials into selected cells ~30~

of honeycomb structures in which the open ends of the cells or the arrangement of the cells across the end ace may be somewhat distorted is an elastic mask described and claimed in U.S. application Serial No. 283,734, filed July 15, 1981, and issued as U.S. Patent ~o. 4,411,856 entitled METHOD ~ND APPAR~TUS FO~ HIGH SPEED MANIFOLDING
OF HONEYCOM~ STRUCTURES, which is assigned to the assignee of this applicakion. An exemplary elastic mask 50 is depicted in Figs. 7 through 7b together with an exemplary honeycomb structure 10 with which it is usedO The mask 50 consists of a substantially plate-like body section 51 having a plurality of openings 52 extending substantially axially therethrough between an upstream face 53 and downstream face 54. A second plurality of protrusions 55 is also provided extending in a substantially axial direction from the downstream face 54. The openings 52 and protrusions S5 are spaced wi~h respect to one another and sized so as to coincide with selected cells 11 when the mask is fitted to an end face 12 (or 13) of the structure 10. A portion of the openings 52 and pro~rusions 55 are depicted in Fig. 8a in a view of the downstream face 54 of the mask 50. The openings 52 and protrusions 55 are alternated with one another along rows and columns parallel and perpendicular, respectively, to the line 56 o Fig. 7a so as to coincide with alternate cells arranged in rows and columns, respectively, at the end face 12 (or 13) of the structure ~0. The mask 50 is fitted to th~
end face 12 (or 13) of the struc~ure 10, as indicated by the arrows 57 in Fig. 7, with the downstream face 54 flush against the ends of the cells 11, as depicted in Fig. 7b.
Preferably, the protrusions 55 are also elastic and taper as they extend away from the downstream face 54 from a cross-sectionaldiameter equal to or greater than a cross-sectional diameter less than the minimum diameter of the open, cross-sectional area o the cell ends into which ~2~

they protrude. The protrusions 55 assist in aligning the mask to the end face with its openings opposite the propex cell ends and temporarily block the cell ends into which they are inserted preventing ~he plugging or other flowable material being charged through the mask 50 from entering those cells. A more detailed description of the fabrication and use of the mask 50 i5 provided in the aforesaid U.S.
Patent Number 4,411,856. A preferred embodiment for fitting the mask 50 to an end face of a honeycomb structure is provided in European Patent No. 8230366.1. A preferred embodiment ~or fitting the mask 52 and end face of a honeycomb structure involves sintering the mask with one end face of the honeycomb structure and then vibrating the mask into alignment against that end face. With its openings exposing the first subset of cells and its plurality of protrusions engaging in equal plurality of the remaining cells. I a pair of masks is provided, first one mask is sintered with one end phase of the honeycomb structure, and then vibrated as men~ioned before, and there-after the remaining mask is approximately sintered with the r0maining end ~ace and then is vibrated into alignment against that remaining end face, with its openings exposing substantially all of the remaining cells and its protrusions engaging on equal plurality o the first subset of cells.
It will be appreciated that the described embodiments are exemplary and that variations and modifications may be made with respect to each. For example, although the first embodiment of Figs. 2 through 4 was depicted in Fig. 5 with a press apparatus for 3Q charging a plastically formable or other highly viscousmaterial into selected cell ends, it is envisioned that the apparatus 20 may be used to charge less viscous materials such as a plugging cement slurry into selected cell ends. One way to accomplish this would be to position the honeycomb structure on its side with its end faces 12 and 13 in a vertical orientation. The apparatus :~2~33~

~0 is fitted to an end face in the manner described with its hollow tubes extending into the selected cell ends.
A cement slurry is charged against the upstream face 22 of the mask and injected through the hollow tubes 24 into the cell ends 11 while the mask 20 is slowly withdrawn from the end face 12 of the structure 10. The mask 20 would be withdrawn at the rate at about which the slurry is being deposited into the cell ends. The flow of slurry would be halted just before the hollow tubes 24 clear the end face of the structure 10. The structure 10 may be rolled or vibrated to assure distribution of the slurry across the cell end. Also, in accordance with Montierth's teaching in the aforesaid U.S. Patent Number 4,411,856, the plugs 40 of the second embodiment depicted in Figs. 6 through 6c may be made of a flexible or elastic material and in a tapered configuration similar to the protrusions 55 of the mask embodiment of Figs~ 7 through 7b so as to conform to or temporarily seal the cell ends into which they are inserted.
We shall now describe the embodiments of the invention shown by Figures 8-17.
Fig. 8 depicts an exemplary mask apparatus 120 and a honeycomb structure 121 with which it is used for orming a solid particulate filter body in which the cells 127 are sealed in a checkered pattern as indicated in Fig. 12. The mask 120 consists of a body 122, having a pair of opposing, typically planar, outer surfaces 123 and 124 (see Figs. 9-11). A number of openings 125 extend through the body 122 between and through the opposing outer surfaces 123 and 124. A number of protrusions 126 extend from the downstream face 124 of the mask 120. The central longitudinal axes of the openings 125 and pro~rusions 126 are typically normal to those sur~acesl24 although it is possible and in certain situations may be desirable to have the openings 125 ~1 ~¢D3(~6~

incline in a uniform direction with respect to the surface 124. When the mask 120 is applied to an end face 128 or 129 of a honeycomb structure 121, the openings 125 allow a sealant or other flowable material to pass through the mask 120 into those cells 127 of the honeycomb structure 121 opposite each opening 125. Again, the protrusions are typically normal to the surface 124 but may be inclined, if desired or required, with respect to that outer surface 124.
The honeycomb structure 121 has a large number of adjoining hollow passages or cells 127 which extend in a substantially mutually parallel fashion through the structure between its end faces 128 and 129 (hidden~. The end faces 128 and 129 typically are substantially square or perpendicular to the central longitudinal axes of the cells 127 but may be inclined thereto if desired or required.
In such case the protrusions must be comparably angled so as to fittably engage the cells and allow the mask to sit flush to the end face. The cell axes desirably align substantially with those of the protrusions 126 and openings 125, making fitting of the mask 120 to ~he end faces 128 and/or 129 easier, and direct the flowable material passed through the openings 125 directly into the cells for uniform filling across the cross-sections.
The cells 127 are formed by a matrix of thin, intersecting walls 130 which extend across and between the end faces 128 and 129. For solid particulate filter bodies, the walls 130 are also porous and continuous across and between the end faces 128 and 129. The structure 121 may also be provided with an outer skin 131 between the end faces 128 and 129 surrounding the cells 127.
A honeycomb structure 121 may be provided from any of a variety of suitable materials including metal, ceramics, glasses, paper, cloth and natural or man-made 3~

organic compounds, as well as combinations thexeof, by any method suitable for the materials selected. For the production of solid particulate filter bodies, porous walled honeycomb structures may be conventionally formed by extrusion from sinterable mixtures in the manner described in UOS. Patents 3,913,384 and 4,008,003.
Cordierite compositions preferred for forming substantially thermostable ceramic honeycomb structures with various degrees of open porosity, are described in the aforesaid 10 European Patent No. 81302986.5 and in the copending Canadian application serial No. 380,875. An impervious, unglazed, sintered manganese-containing ceramic material has as its major and primary crystal phase a cordierite crystal structure, has an analytical molar composition of about 1.7-2.4 RO 1.9-2.4 A12O3 4.5-5.2 SiO2 and is made of mineral batch composition selected from (a) wholly raw ceramic material wherein RO comprises~ as mole %
of RO, about 55-95~ MnO and 5-45% MgO, and (b) at least about 50 wt.% prereacted cordierite material and the . 20 balance thereof is raw ceramic material, and wherein RO
comprises, as mole % of RO, about 5-40% MnO and 60-95%
MgO. It will be appreciated that a subject mask however, may be used with honeycomb structures 21 formed from other materials and/or by other methods.
- 25 The open, transverse cross-sectional areas of the cells 127 are square and are arranged at the end faces 128 and 129 in mutually parallel rows and mutually parallel columns which are mutually perpendicular to one another.
It will be appreciated that the rows and columns may not 30 be exactly parallel and perpendicular due to manufacturing limitations in fabricating the honeycomb structure 121.
The square, cross-sectional geometry and the row and column arrangement of cells at the end faces depicted in this application are exemplary. A mask 120 may be fabricated to fit a variety of cellular arrangements and cellular cross-sectional geome~ries and to provide a variety of selected cell charging patterns.
The positioning of the openings 125 in and protrusions 126 on the mask 120 are made with respect to the cells 127 of the honeycomb structure 121 with which the mask is used. Each opening 125 is positioned on the mask to coincide with the open end of a cell to be charged 10 with a filling material through the mask when the mask is properly positioned over the end face (see Fig. 11).
The openings 125 are suitably sized to expose the open ends of the selected cell or cells sufficiently for charging but not so large as to expose part or all 15 of any other cell not to be charged. Larger openings can be provided to expose several adjacent cells if desired.
Each protrusion 126 is similarly positioned on the mask to suitably engage and is preferably siæed to seal a single cell at the end face 128 or 129 over which 20 the mask 120 is fitted. The protrusions 126 are preferably elastic and taper from a diameter at their base which is e~ual or larger than, to a diameter at their tip which is ~maller than the minimum cross-sectional diameter of the open end of cell with which they engage. Cone-topped 25 cylindrical protrusions depicted in Figs. 8-11 are easy to foxm as are other shapes having a surface of rotation (i.e. cones, domes, domed cylinders, bullet shapes etc).
The protrusions need not taper along their entire length although it is desirable that t~e protrusion tip distal to 30 the mask body 122 be tapered to provide some tolerance during initial registration of the protrusions with the cell ends. The included angle of taper T between the protrusion side walls 133 (see Fig. 11~ near the distal tip of the protrusion 126 should be less ~han 90 degrees 35 and desirably between approximately 10 and 50 degrees.

The mask 120 is formed from a flexible material impermeable to and non-reactive with the sealing material or other flowable material to be charged through the mask 120. Flexibility allows the mask 120 to conform to unevenness and some distortions and deformities in the cellular arrangements at the structure's end faces 128 and 129. This characteristic is significant because in many cases, notably the ceramic arts~ undistorted and undeformed honeycomb structures cannot be provided with regularity 10 by conventional manufacturing techniques. This problem increases with increasing cell densities, increasing end face dimensions and decreasing structural stiffness during formation of the structure, and is relatively significant with respect to a mass fabrica~ion of ceramic-based filter 15 bodies such as the diesel particulate filter embodiment described in the aforesaid European Patent No. 81302986.5.
Preferably the mask and its protrusions are also elastic.
Such masks are most conveniently formed monolithically from any of several possible elastomers (i.e., elastic 20 polymers) by casting or injection molding in a manner to be later described. Elastic masks have been successfully ~ormed ~rom various silicones and urethane although it is envisioned that other flexible materials including other elastic pol~mers may be used. Elasticity also allows 25 the mask 120 and protrusions 126 to A~)""~ cellular spacing distortions at the end faces 128 and 129 and the tapered protrusions to sealably fit the open ends o cells 127 withou~ damaging them when the mask 120 is applied.
It is envisioned that the flexible masks will be fabricated 30 from any of several moldable, polymerizable resins including silicones and urethanes or o~her materials also having a Durometer Shore A value ranging between approximately 10 and 70 (See ASTM Standard D-1706~ and a Young's (E) Modulus of approximately 30,000 psi (about 2110 kg./cm.2~ or less, 35 although a Young's Modulus in the range of approximately 500 to 3000 psi (about 35 to 211 kg./cm. ) is preferred for ~3~
~3 ela~tic masks used in fabricating solid particulate filter bodies from the aforesaid ceramic-based honeycomb structures.
The mask 120 depicted is sized to cover the open end faces i28 and 129 of the structure 121. Protrusions 126 are provided on the ma$k 120 to fi~ably engage each cell which is not to be charged with a sealing material through the mask. It should be appreciated that a protrusion need not be pxovided for each cell which is not to be charged at the covered end face and that many of the protrusions 126 on the exemplary mask 120 of Figs. 8 ~hrough 11 could have been eliminated without detrimental effects. Indeed, because cells at the periphery of an end face may have partial or reduced cross-sectional areas which will make fitting a full-sized protrusion difficult or impossible, it may also be desirable in some applications to reduce the surface area o~ the mask to less than that of the end faces allowing the cells at the periphery of the end face to be charged, or, if that is unacceptable, to eliminate the protrusions at the outer edge of the mask. Similarly, in certain applications it may also ~e desirable to omi~ openings through certain areas of the mask so as to leave two or more adjoining cells unplugged.
Care should be taken to account for any shrinkage which occurs in the fabrication of the mask. If a polymer-izable resin i5 used, it will typically experience shrinkageat a rate which will differ as the proportions of its components and the conditions under which it is cured are varied. Exact sizing of a mask to ~ts honeycomb structure is preferred as dimensional mismatch will make the fitting of the mask to an end face more difficult. It was obsexved that if mask opening/protrusion spacing were excessively undersized or oversi~ed with respect to the corresponding cell spacing the elastic protrusions would "knuckle un~er"
while an elastic mask was being pressed against the end 3S ~ace making fitting impossible. Some tolerance to elastic ;~2~3C3~

mask undersizing has been obser~ed in applying masks approximately .125 inches (3 mm.) thick and ha~ing protrusions about .125 inches (3 mm.~ long and about .07 inches ~about 1.8 mm.~ thick, openings about .086 inches (about 2mm.) in diameter and a ~oung's Modulus of approxi-mately 3000 psi (about 211 kg/cm2) or less to honeycomb structures having cell densities of approximately 100 cells/
sq.in. (about 15.5 cells/s~.cm.) ~hat for very small areas, approximately one-half inch (1.27 cm) in diameter, about 8 10 to 10% undersizing of the mask could be accommodated; at diameters of about 4 inches (10.16 cm) about 4% undersizing of the mask could be accommodated; at a diameter of approximately 6 inches (15.24 cm) approximately 1% under-sizing of the mask could be a~cN~ ted~ No tolerance for elastic mask oversizing was observed although very minor oversizing (less than 1%) might be ~cc~,alL~Led. It is believed that approximately 1% undersi~ing over a 6 inch diameter area could be ac~ ated for other elastic masks (having a Young's Modulus of up to approximately 10,000 psi 20 (about 703 kg./s~. cm.)). Undersizing of the mask to the structure is depicted in Fig. 14f with reference to the centerlines 163 of adjoining protrusions 126 and the c~nterlines 164 of the cells 127 with which they engage.
Fig. 9 is a view of the outer surface 124 of the 25 mask 120 shown in Fig. 8 and depicts a portion of its openings 125 and protrusions 126. The openings 125 and protrusions 126 are alternated with one another along rows and columns parallel or perpendicular to the line 10-10 50 as to coincide with the rows and columns of cells 127 30 at the end faces 128 and 129. Each opening 125 and protrusion 126 of the mask 120 in Fig. 9 will be positioned juxtapose one cell 127 when the mask 120 is applied to either end face 128 or 129. As the mask 120 has been fabricated to fit and expose in a checkered pattern the 35 square cells of the honeycomb structure 121, the ~Z~

openings 125 and protrusions 126 are formed in rows mutually parallel to the line 10a-lOa. The line 10a-lOa bisects a row of evenly spaced protrusions 126. Rows of evenly spaced openings 125 and evenly spaced protrusions 126 are alternated with one another across the mask surface 124 to either side of the row of protrusions bisected by line 10a-lOa. These rows of protrusions 126 and openings 125 will align with the diagonals of the cells 127 when the mask 120 is fitted to ~he end face 128 or 129. If a 10 plugging material is charged through the openings 125 in the mask 120, the open ends of the cells 127 in an adjoining end face 128 or 129 will be filled in a checkered or checkerboard pattern as is indicated in Figs. 1~ and 12a.
The mask 120 may be hand fitted to an end face 15 128 or 129 of a honeycomb structure in the manner depicted in Fig. 10. It is suggested that the protrusions 126 ak or near one outer edge of the mask 120 be fitted into corresponding cells 127 near an edge of the end face. The mask may be moved laterally for very short distances in a 20 variety of directions across the end face and rotated in opposing directions to start the engagement of one or more of the protrusions with appropriate cells in the end face.
Other protrusions 126 are fitted into appropriate corres-ponding cells in directions radiating from the initially 25 aligned protrusions as indicated by the arrows extencling acro~s the outer surface 123 of the mask 120 in Fig. 10.
It is helpul to stretch an undersized mask and vibrate it slightly back and forth across the end face 128 or 129 during this process to align the protrusions 126 with the 3Q appropriate cell ends. Once it is sensed that the protrusions have aligned with underlying cells, the outer surface 123 of the mask is pressed down to insert the aligned protrusions into the cell ends. This process is continued until the mask 120 is fitted flush acxoss the 35 entire end face 128 or 129 of the structure 121.

3~

A solid particulate filter body is formed by charging a flowable sealing material through the openings 125 in the mask 120 into a subset of alternate cells at one end face 128 or 129, removing the mask 120, applying it cr a comparable mask to the remaining end face of the structure 121 with the openings 125 aligned over the remaining alternate cells and charging the sealing material into those cells. The structure and sealing material may be cured or fired, i appropriate. Foam-type cordierite ceramic cements, which are compatible with the aforementioned cordierite structures and chargeable with the subject mask, are described in the aforesaid co-pending Canadian application Serial No. 380,875 entitled PARTICULATE FILTER AND MATBRIAL FOR PRODUCING THE SAME, filed June 30, 1981, and a preferred composition of this cement is described in the aforesaid European application No. 81302986.5. A foamable particulate ceramic cement capable of forming a sintered cordierite foamed ceramic mass may consist essentially, by weight, of: 1-40%
cordierite grog, 99-60~ ceramic base material and an e~fective amount of a foaming agent to effect oaming of the cement upon firing to produce the foamed ceramic mass.
The base material is a raw ceramic material that has an analytical molar composition consisting essentially of abou~ 1.7-2.4 MO 1.2-2.4 A12O3 4 5-5 4 5i2 wherein MO comprises, as mole ~ of MO, about 0-55% MgO and at leas~
45% MnO. The grog is a ceramic material that has been previously ~ired and comminuted, and that has an analytical molar composition consisting essentially of about:
1.7-2.4 RO 1.9-2.4 A12O3 4.5-5O2 SiO2 wherein RO
comprises, as mole % of RO, MnO in an amount of 0% up to a mole % that is about 20 mole ~ lower than the mole %
of MO that is MnO and the balance is substantially MgO.
It is envisioned that the subject masks may also be used to charge non-foaming cexamic cements as well as other ~2~3~

flowable materials o various viscosities into selected cells of honeycomb structures for various applications.
A filter ~ody formed rom the structure 1~1 of Figs. 8 through 11 is depicted in Fi~s. 12 and 12a with 5 alternate cells 127 sealed in a checkered pattern on end face 128. This pattern is reversed on the end face 129 as can be seen in part in Fig. 12a, a cross-sectioned view along a row of the cells in the filter body of Fig. 12 depicting the plugs 132 formed by the sealing material 10 charged through the mask openings 125. Flow of a contam-inated fluid through the filter is indicated in ~ig. 12a by arrows 134. The cont~min~ed fluid enters through the "inlet" cells 127 open at the left ("inlet") end face 128, passes through the thin, porous walls 130, into 15 adjoining "outlet" cells open at the right ("outlet") end face 129, and in the process leaves the cont~m;nAnts too large to pass through the walls 130 in the inlet cells open at end face 128. Additionally the plugs 132 may be formed with open porosity equal to or less than that of the thin 20 walls 130 and allow some fluid flow therethrough which will not impair the operation of the filter body. Operation of the filter is described in more detail in the aforesaid European application No. 81302986.5.
A second aspect of the in~ention is die apparatus 25 and methods for using the same to fabricate a flexible or elastic mask similar to that depicted in Figs. 8 through 11.
first mask forming apparatus is depicted in cross-section in Fig. 13a and consists of a mold 140 having a mask forming outer surface 141, typically planar, and a multiplicity of 30 bores 142 extending through the mask forming surface 141 and mold 140 in directions essentially normal to the mask forming surface 141. A cavity 144 in ~ich the mask body is formed is defined by a ridge 143 which extends outwardly from the mask forming surface 141. The bores 142 foxm the 35 protrusions 126 of the mask and axe desirably tapered inwardly as they extend away from ~he mask forming

2~

surface 141, preferably at an included angle bet~en approximately 10 and 50 degrees. After being cast in a manner to be subsequently described, the mask is removed from the mold 140 and openings 125 made through the body of the mask 120 at selected locations among the protrusions 126 as indicated in Fig. 13b. The openings 125 may be made by any suitable means such as but not limited to boring, cutting, drilling (depicted), burning and melting. If formed from anelas~ic polymer, the mask may be chilled to make the operation easier to perform. In the preferred embodiment, the openings 125 are also essentially normal to the outer downstream surface 124 of the mask 120 from which the protrusions 126 extend.
Fig. l~a depicts a cross-sectioned profile view a second mask forming apparatus. Like the first apparatus of Fig. 13a, the second apparatus of Fig. 14a consists of a mold 150 having a plurality of tapered bores 152, a mask forming surface 151, and a ridge 153 which forms with the mask forming surface 151 a cavity 154 within which the body of the mask is formed. The second apparatus further includes a plurality of means 155, such as pins, for forming an equal plurality of openings through the mask. It is preferred that the tops of the means 155 form a common plane with the top of the ridge 153 to assist in forming a flat outer surface on the mask, as will be subsequently described.
A mask 120 formed within the apparatus of Fig. 14a is depicted in cross-section in Fig. 14e and has a pair of opposing outer surfaces 123 and 124, a first plurality of openings 125 extending through and between the outer surfaces 123 and 124, and a second multiplicity of protrusions 126 extending from the outer surface 124. Again, the protrusions 126 are preferably tapered downward at an included angle of between about 10 and 50 degrees and ~he protrusions 126 and the openings 125 extend essentially normally from the outer surface 124.

~L~63 3~

Simple working models of die apparatus corres-ponding to those depicted in Figs. 13a and 14a through 14d can be formed from transverse cross-sections of khe honey-comb structures with which the masks are to be used. To form the die of Fig. 13a, the cells of a honeycomb section are filled with an easily removed solid material such as wax and affixed to a supporting plate using wax or a suit-able adhesive. The wax or other solid material is removed from selected cells in which protrusions of the mask will 10 be ~ormed. The outer perimeter of th sectioned structure is then surrounded with a collar to form ridge 143 and a selected polymer is cast in the mold thus formed. A die apparatus similar to that depicted in Figs. 14a through 14d may be formea by the additional insertion of pins into 15 selected cells of the sec~ioned structure. A Conap, Inc. No.
TU-65 urethane was mixed accordincJ ~o directions and cast in such an apparatus to establish the feasibility of the casting processes. After a room temperature cure for about 18 hours, the solidified mask was removed from the die and 20 oven heated at about 200 Fahrenheit (93 Centigrade) for about 16 hours to complete curing. Preferably, however, the die apparatus is fabricated from a ri~id, machinable material such as metal ~or precise dimensioning of the formed mask. It will further be appreciated that the die 25 apparatus of Figs. 13a and 14a through 14d can be constructed in two pieces consisting of a flat plate ha~ing a mask forming surface~141 or 151 with, in the latter case, openings forming means 155 protruding therefrom and bores 142 or 152 extending therefrom and therethrough and a second plate 30 having a center cutout which is attached to the first plate 140 or 150 to provide the ridge 143 or 153 forming the cavity 144 or 154.
A mask is formed in the mold 150 in the manner depicted in Figs. 14a through 14d. The mold 150 is cl~aned 35 with a suitable agent such as acetone or xylene prior to 33~

forming each mask. After cleaning the inner surfaces of the mask forming cavity 154 and bores 152 are coated with a suitable releasing a~ent, such as a 2001 ratio by weight solution of methylene chloride and ~ohnsonTM Paste Wax.
A suitable polymerizable resin ("polymer'!) is mixed and de-aired by an appropriate device such as a vacuum chamber.
A mass of mixed and de-aired polymer 156 is applied to top of the mold 150 and is worked into the cavity 154 and bores 152 with a suitable tool 157 such as a spatula or putty 10 knife. The mold 150 may be mounted on a vibrator platform 158 and/or a vacuum souxce 159 may be applied to the ends of the bores 152 opposite the mask forming surface 151 in order to work the polymer into the bores 152 and recesses of the cavity 154. Other devices such as ultrasound sources 15 (not depicted) may be employed in working the pol~er into the cavity 154 and bores 152. The surface of the polymer is leveled with the upper surfaces of the ridge 153 and opening forming means 155 with the tool 157. The extrusion of the pol~ner material through all of the openings of the 20 bores 152 at the bottom surface 1~1 o~ the mold 150 indicates that the cavity 154 and bores 152 are filled.
The tops of the means 155 then are scraped clean with a sharp edge 160 such as a razor as depicted in Fig. 14b, leaving a smooth outer ~ace on the molded polymer. The 25 polymer is then cured in a manner appropriate for the materials selected. The curing of many polymers may be accelerated by baking as is depicted in Fig. 14c. After baking, the mold 150 and cured polymer are removed from the oven and are allowed to cool. Once the mold 150 is 30 sufficiently cooled to be handled, the polymer extruded through the bottom of ~he bores 154 and beyond the bottom surface 161 of the mold 150 are removed by suitable means 162 such as a razor blade or scraper as indicated in Fig.
14d. The cured polymer is then pulled from the mold and 3S trimmed to an appropriate size, if required. Except for ~3~

the cleaning of the pin tops (Fig. 14b), the same steps are followed in casting a mask in the mold 140 (Fig. 13a).
Again, openings must be formed through the mask after its removal from the mold 140 (Fig. 13b).
Yet another apparatus, an envisioned compound die for forming a mask, is depicted in an exploded view in Fig. 15a and in a sectioned profile view in Fig. 15b, and consists of a first die piece 165 having means 166 to form the plurality of openings in the subject mask, a second 10 die piece 167 for forming the flexible protrusions extending from one face of the mask and a third die piece 168 positioned between the die pieces 165 and 167 for stripping the subject mask from the die ~fter being formed. This compound die apparatus allows faster and easier mask 15 fabrication than either of the die apparatus depicted in Figs. 13a and 14a through 14d. The first die piece 165 has an essentially planar bottom outer surface 169 ~hidden) from which extends a plurality of means 166 such as pins or tubes for forming the openings 125 in the mask 120 20 (see Figs. 8 through 11). The second die piece 167 has an upper outer surface 170 designed to contactably mate with the ends of the means 166. For ease of use it is sug~ested that the ends of the means 166 be flat and form a common plane and that the outer surface 170 of the 25 second die piece 167 also be planar. The second die piece 167 is further provided with a plurality of bores 171 extending therethrough from the outer surface 170. The walls of the bores 171, which form the protrusions 126 of the mask 120 (Figs. 8 through 11), extend normally away 30 from the outer surface 170 for a short distance and then taper inwardly, suggestedly at an included angle of between approximately 10 and 50 degrees as they extend away from the outer surface 170. The third die piece 168 is essentially planar and is positioned within a ca~ity 172 35 formed between the first and second die pieces 165 and 1~7, ~3~

respectively, when the opening forming means 166 are positioned against the second piece outer surface 170 ~see Fig. 15b). The third die piece 168 is provided with a second plurality of bores 173 equal to the number of means 166 which are positioned and sized so as to allow the third die piece 168 to be slid along the means 166 and posi~ioned against the surface 169 of the first die piece 165 with the means 166 extending completely through and protruding from lower surface 174 of the third die piece 168. The 10 tolerances between the plurality of bores 173 and means 166 should also be suficiently tight to prevent the intrusion o~ polymer and the formation of flash during the fabrication of the mask. However, if flash is formed it may be removed by suitable means such as water jetting or burnishing. The 15 mask is formed between the lower surface 174 of the third die piece 168 and upper surface 170 of the second die piece 167.
A mask may be cast in the third die apparatus in a manner similar to that used with the first two die 20 embodiments. The die pieces 165, 167 and 168 are cleaned and a removal agent applied to the mask forming surfaces.
A suitable polymer is mixed, de-aired and applied to the upper face 170 of the second die piece 167 and is worked into the bores 171. The second piece 167 may be formed 25 with a ridge 175 to contain the polymer during this process.
The mated first and third die pieces 165 and 168 are pressed against the second die upper surface 170 and held in place by suitable means 176 such as clamps (depicted) or screws or nuts and bolts during the curing of the polymer.
30 If the peripheral ridge 175 is provided, it should be low enough so ~hat one or more narrow gaps 177 are formed around the cavity 172 through which excess polymer material may be squeezed (see Fig. 15b). The third die piece 168 is held against the first die piece 165 by the polymer 35 between the piece 168 and the second die piece 1~7. After curing, polymer extruded through the tapered bores 171 is

3~

again removed by a suitable ~ool such as a razor kni~e (see Fig. 14d). The means 176 used to hold ~he three die pieces together are removed and the second die piece 167 removed from t~e first and third die pieces 165 and 168.
Frictional forces will hold the mask 120 to the openin~
forming means 166 extending through the mask ~orming lower surface 174 of the third die piece 168. This mask forming lowersurface 174 eliminates the separate upper mask surface forming step required in the first ~wo die embodiments (see particularly Figs. 14a and 14b). The mask 120 thus formed within the cavity 172 and tapered bores 171 may be stripped from the opening forming means 166 by sliding the third die piece 168 along the means 166 away from the first die piece 165. If desired or necessary, the formed mask may be trimmed to a suitable shape for use.
Comparable die pieces may also be used for injec-tion molding of the mask. In an injection molding apparatus, means are provided for in~ecting the polymer or other flowable material into the cavity, such as through the g~p(s) 177.
Sintered honeycomb structures with which the described mask have been used, typically experience shrinkage during their drying and sintering cycles which vary with compositional and drying/curing schedule variations. By varying polymer mixtures and/or curing schedules, the shrinkage and thus the relative dimensions of the flexible mask fabricated may also be controllably varied. In this way, a single die appaxatus may be used to fabricate different masks accommodatin~ honeycomb 3a structures experiencing-siightly different shrinkages.
Again, exact sizing of the mask to the structure is desired but to the extent that that goal cannot be achieved slight undersizing is preerr~d to oversizing. Several silicone ormulations have been successfully cast using a 35 die apparatus similar to that depicted in Figs. 14a ~26~3~

through 14d formed from machined ~rass plates incorporating steel, opening f~rming pins. In each case, the pol~mer components were mixed,de-aired with an approximately 28 inch (71.1 cm.~ mercury vacuum for about 20 minutes, applied to the die apparatus and hea-ted for about 8 to 10 minutes at about240 to 260 Centigrade to accelerate curing. A~ter cooling and remo~ing from the die apparatus, some masks were subjected to an additional post-curing cycle in which each was again heated at approximately 230 to 250 Centi-grade for about 16 hours. In each such case, post-curing yielded additional shrinkage. Silicone mixtures which have been successfully cast and their ohserved linear shrinkage from original die ~ ions under the a~oresaid oven curingand where indica~ed, post-curing schedules are as follows (all ~ are by volu~e except where otherwise indicated2.

ADDI TIONAL TOTAL
CU~E POST-CURE SHRINK-20 SHRINKAGE SHRINKAGE AGE 9~
POLYMER ~ (APPROX. ) ~ (APPROX. ) (APPROX. ) 1. Dow Corning Q3-9595*
silicone resin (50 A component mixed with 50% B component) 3. 0-3. 3 0.5-0.8 3. 8-4.0 25 2. Dow Corning Q3-9590*
silicone resin (50% A
component mixed with 50% B component~ 2.3-2.61. 4-1.7 about 4.0 3. Dow Corning Q3-9595*
(50% component A mixed with 50 % component B2 mixed with additional 10% (by weight) Dow Corning X3-6596A* sili-cone resin (.A compo-nent only) 2.3~3.00.8~1.0 3.8-4.0

4. Dow Corning X3-9592*
(50% ;~ component mixed with 50% B component) 2. 5-2. 80.7-1.0 3.2-3.5 *TradOEk ~3qO ~

ADDITION,A,L TOTAL
CVRE P(:)ST-CURE 5EIRINK--INRAt~E SII E?<INKA(7E AGE ~6 POLYMER 9d (:APPROX. ~ % ~:APPROX . ~ (APPROX . )

5. 50% (by weight) Dow Cornin~ Q3-9595* B com-ponent silicone resin mixed with 50% (hy weight) Dow Corning X3-6596*A component silicone resin 2.8-3.0 about 1~0 3.8~4.0

6. Dow Corning X3-6596*
silicone resin (50% A
component mixed 50% B
componentl 1.9-2.1 0.7-0.9 2.7-3.0

7. 25% (bv weight)Dow Corning Q3-9590*sili-cone resin (50% A
component mixed with 50~ B componen~) mix-ed with 75~ (by weight~ Dow Corning X3-6596* silicone resin (50% A component mixed with 50% B component] 2.2-2.4 1.0-1.2 3.5-3.7

8. 25~ Dow ~orning Q3-9590*silicone resin (50% A componen~
mixed with 50% B com-ponent) mixed with 75% Dow Corning X3-6596*
silicone resin (50% A
component mixed with 50% B component) 2.5-3.0

9. 90~ Dow Corning Q3-9595*
silicone resin (50 component mixed with 50% B componentl mixed with 10% Dow Coxning 3X-6596*A component silicone resin 2.5-3.0

10. Dow Corning No. 732*
silicone resin (50%
A component mixed with 50~ B componentl 1.8 *Trademark ~3~

ADDITIONAL TOTAL
CURE POSTCURE SHRINK-SHRINKA~E SHRINKAeE A~E %
POLYMER %-(~PPROX.~ ~APP~OX.) (APPROX.

11. Dow Corning No. 734*
silicone resin (50%
A component mixed with 50% B component) 1.8 Silicone oils have also been added to silicone resins to obtain even greater shrinkages. In each case, the oil was mixed into a mixed silïcone resin, de-aired, cast and heated in a mold through the a~oresaid curing schedule (230 to 260 Centigrade ~or 8 to 10 minu~es~ but was subjected to a post-cure baking at about 230 Centigrade ~or only about 4 hoursO
The mixtures examined and their cure, additional post-cure and total shrinkages are as ~ollows (all % are again by volume unless otherwise indicated).
ADDITIONAL TOTAL
CIJRE POST-~URE SHRINK-SEIRINKAGE SH~INKAGE AGE ~
POLYMER~ (APPROX. ) % (APPROX. ~(APPROX. )

12. 82.5% (by weiyht~Dow Co~ning X3-6596* sil-icone resin (50% A
component mixed wi~h 50~ B component~ mixed with 17. 5% Dow 200 Sil-icone Oil 20CS*2.6-2.8 1.8-2.0 4.4-4.6

13. 90~ (by weight) Dow Corniny X3-6596* sil-icone resin (50~ A
component mixed with 50% B component) mixed with 10~ Dow 200 Silicone Oil 500CS*2.4-2.7 0.6-0.8 3.1-3.5 Other ratios and curing schedules should yield a range of shrinkages. At least one silicone resin, Dow Corning 184*, could not be cast on the aforesaid ~old apparently due to in-teraction with the brass~ Adverse reactions may be encountered with other die material and polymer mixes.

*Trademark 31~

Yet another aspect of the in~ention are mekhods and appaxatus for manifolding selected cells o~ a honeycomb structure as ~ould be done during the abrication of solid particulate filter bodies, using the flexible, elastic masks heretofore described. An exemplary press apparatus 180 is depicted in cross-section in ~ig. 16. A ~lexible mask 120 and honeyco~b structure 121 are pro~ided in the manner pre~iously described. The mask 120 has been applied to an end ~ace 128 of the honeycomb structure 121 with its protrusions 126 and openings 125 aligned with the ends of alternate cells 127 at the end face 128. Slight under-sizin~ o~ the mask 120 will provide mechanical self-locking of it to the structure 121. Moreover, it is suggested that a ~lexible tubular collar 181 of a suitable material such as neoprene be stretch ~itted over the peripheral edges o~ the mask 120 and outer sidewall 131 of the structure 121 adjoining the end ~ace 12B to assist in holding the mask 120 to the structure 121 and in sealing the structure 121 over an oriice 183 on the upper face 194 o~ a press head 186. An adjustable, flexible clamp 182 is provided around the collar 181 so as to better secure it to the mask 170 and structure 121. The press apparatus 180 comprises ~he press head 186 supported bv a frame 188. The head 186 is equipped with a piston 184 slidably mounted in a bore 185 for charging a cement mixture through the orifice 183 over which a honeycomb structure 121 is secured. Prior to charging, the piston 184 is backed away su~ficiently ~rom face 194 to form a chamber above the piston head which is loaded through the orifice 183 with a suitable amount of a ceramic cement such as the ~oam-type cements previously referred to. The mask 120 and structure 121 mounting the collar 181 and clamp 182 are then placed over the orifice 183 and held in place by suitable ~eans such as a bar 189 placed across the remaining end face 129 of the structure 121 and held into place by suitable means such as bolts 190 extending through the bar and into suitably threaded bores 191 o~
the press head 186. The piston 184 is then advanced 3~

towards the exit ori~ice 183 by ~eans of a hand-operated screw 187 or other suitable ~eans and, in the process, presses the cement mass ~ove the piston 184, against the mask 120, and through its openin~s 125 into the proximal open ends of the cells 127 juxtaposed to the openings 125 forming cement plugs 192. During this step, the flexible collar 181 also seals the circum~erential edge o~ the orifice 183 preventing the cement *rom being foxced out past the end ~ace 128~ Similar plugs 193 have already been formed in the ends o~ the re~aining alterna~e cells 127 proximal the end ~ace 129 in a previous ~illing. The structure 121 may then be removed ~rom the press apparatus 180 and the flexible collar 181 and mask 120 removed from the structure 121, which is ready ~or ~iring to sinter plugs 192 and 193 and structure 121, if appropriate.
Parallel work by the applicant has resulted in a double headed cement press for simultaneously ~illing both ends of a honeycomb structure using a pair of the subject masks. Where a pair of masks are used, they may be held in place during handling of the honeycomb structure before its insertion into the press by providing under~
sized masks or by temporarily securing the masks to the ~nd ~aces of the honeycomb structure with a mild adhesive which will allow their easy removal after charging.
It is fur~her envisioned that the subject mask 120 may be ~itted across the feed orifice 201 of a filling device such as a cement press having a press head 200 as depicted schematically in Fig. 17 so as to ~eed a *low-able material, in this embodiment a plastically ~ormable cement, into a honeycomb structure fitted to the filling device's ~lexible mask 120. The ~ask 120 is secured to the press head 200 in a suitable collar 202 by an annular plate 203 or other suitable mean~. The collar 202 is secured across the ~eed orifice 201 again by suitable means such as threading 204 or ~asteners (not depictedl~
The s~ructure 121 is brought to the mask and ~i~ted 3~

against its e~posed protrusions 126. Cement (shading~
is fed into a cavity 206 foL~ed in the press head 200 between a piston 205 and the upstrea~ face 123 of the mask 120 through appropriate means such as feed tubes 207. The piston 205 is advanced as indicated by arrow 208 and forces the ce~ent against the mask 120 and through its openings 125 into the open ends of the opposing subset of cells 127. I~t is further envisioned ~or ~abrication of solid particulate filter bodies and other honeycomb structures manifolded at both their end ~aces that a second press head similar to the head 200 depicted be provided with an appropriate mask 120 for simultaneous charging of both end faces of the structure.
A preferred embodiment of a method for automatically fitting a subject flexible mask to a honeycomb structure ~ill be described with reference to ~igures 18-27.
According to the invention, a~ter being placed on the end face 312, as indicated by the arrows 322, the ~ask 311 is xapidly vibrated about and around the center of the end face 312 until it moves into lateral and angular alignment with its protrusions 315 enga~ing the cells 316.
In Fig. 18, the honeycomb structure 310 has been positioned on the surface 323 o~ a mechanical vibration source.
Preferably the surace 323 imparts a rotational vibrating motion. A suitable device has been constructed by mounting to the base of a commercially available rotary vibratory parts ~eeder in place of its feeder bowl, a flat plate.
The surface of the plate ro-tates back and forth through a short arc about its center, the motion being sharp in one direction and relatively slower in the return direction.
The surface experiences no net lateral or rotational movement but a suf~iciently light object (such as a structure and mask~ placed upon its sur~ace will rotate, and, i~ placed o~f~center rom the rotational axis, orbit in short hops about the rotational axis. Desirably, means are also provided to control the amplitude of the vibra-tory motion generated and thereby control the rotationalspeed of the mask and/or structure. Yibration amplitude o~ the pre~iously re~erred to parts feeder was controlled by means of a rheostat. A Yibrational frequency of about 60 hertz has been used to seat the described masks but it is envisioned that a wide range o~ frequencies, approxi-mately 30 to 200 hertæ or more, may bP employed success~ully in seating the described flexible masks.
Other frequency ran~es may be found desirable for other applications of the invention. Rotakional vibration is trans~itted ~rom the surface 323 to the mask 311 resting on the end face 312 through the structure 310 which is preferably centered over the axis of rotation o~ the surface to minimize lateral movement of structure 310 and mask 311. Alternatively, it is en~isioned that the mask 311 mav be directly contacted by a vibration source and vibrated into alignment. Also it is envisioned that the positions of the mask 311 and structure 310 may be reversed with the ~ask 311 on the surface 319, its protrusions extending upwards. Although random, linear or orbital (planar, orbitting movement without rotation of the vibrating plane) vibration may be usedr rotational vibration in the plane between the end face 31~ and mask 311 is preferred as it causes the mask 311 to rotate steadily around the end face 312 facilitating angular as well as lateral alignment. Rotation of the mask with respect to the end face may have to be otherwise accomplished if randon, linear or orbital vibration is used. PreEerably, the structure 310 is temporarily held in position on the surface 319 to better transmit the ~ibrational motion from the surface 319 to the mask 311.
The structure may be held by any of several suitable methods including the use o~ a re~ovable temporary adhesive, clamps, or a pair o~ pins or the like extending through the plat~orm surface and into a pair of the structure's cell ends sitting on the surface 319.

3~
~1 A collar 324 has heen attached to the side walls 318 of the structure 310 and extends above the end face 312 50 as to confine the mask 311 within the collar. In this manner, the lateral moY~ment o the axial center of ~he mask 311 across the end face 312 is limited to a s~all predetermined area about the axial center of the end face 312. The faces 320 and 321 o~ the mask 311 can be appropriately si2ed to define the size of the area about the axial center of the end face 312 in which axial center of the mask 311 is con~ined. It is envisioned that in some configurations, proper alignment of a mask 311 and end face 312 or 313 may be achieved simply through orbital vibration without the use of a constraint ~uch as the collar 324. other means of lLmiting the lateral movement bet~een the mask and honeycomb structure will be described subsequently.
To fabricate the solid particulate filter body 325, the mask 311 is aligned over the end face 312 with its openings exposing a flrst subset of cells. A similar mask (not depicted~ is aligned over the end face 313 of the honeycomb structure 310 with its openings exposing a substantially different subset of cells. The exposed cells 316 are plugged with a suitable material passed through the openings 314 of both masks. It will be appreciated, of course, that each end face may be covered with a mask and filled in sequence or that both end faces may first be covered and then filled simultaneously or in sequence. The filter body 325 of Fiys. 20 and 21 has been foxmed from the structure 310 of Figs. 18 and 19 by plugging the cells 316 in a desired checkered pattern at the end faces 312 and 313. The pattern of plugged cells on end face 312, depicted in Fig. 2C, is reversed on the hidden end ~ace 313 as can be ascertained in Fig. 21 where the filter body 325 has been sectioned along a line (row or columnl of cells 316 re~ealing the plugs 326 formed in al~ernating cell ends along the line.

3~

To achie~e the checkered plug~ing pattern e~hihited by the filter body 325 in ~i~s. 20 and 21, the openings 314 o~ the mask 311 u~ed with th~ structure 310 ~ere arranged in mutually parallel rows and columns across the mask surface with pxotrusions 315 located there-between to engage all or substantially all of the remaining alternate cells at the end face~ It will be appreciated that for various applicat~ons other than Eiltering, it may be desirable to plug some cells at both their ends, to leave some cells unplugged or both.
Also, plugging patterns other than the depicted checkered arrangement may be employed. In each case, however, the plugging pattern on each end face of the filter body will be substantially, if not, identically, the reverse of that at the remaining end faceO Typical fluid flow through the filter body 325 is indicated by the arrows 32~.
The aligning of bodies, such as ~lexible ~asks to honeycomb surfaces such as the described end ~aces, may be automated. For the fabrication o~ solid particula-te filter bodies, auto~ation is simpli~ied by using particu-lar honeycomb structures and masks to assure proper cell exposure through the masks at the two end faces.
A first embodiment comprises in part a honeycomb struc~ure such as the structure 310 of Figs. 18 and 19 with the axial centers of its end ~aces located at or approximately at the center of the transverse cross-sectional area of one of its square cells. A pair of so-called "reverse" masks is also provided~ The openings 314 of each of the reverse masks will expose completely or substantially di~ferent subsets of cells ~hen each of the masks is identically located on an end face of this honeycomb structure. Fig. ~2 depicts the area of an end ~ace 312 or 313, about its central cell 329 and adjoining cells 316 o~ the structure 310 arranged as they are arranged across the end faces 312 ~nd 313 in rows and columns. The cells 316 are divided into alternate 3~

subsets which are identified by "X's" and "o's" and yield the desired checkered pattern o~ plugged cells illustrated in Figs. 20 and 21. ~he l'X's" and "o's" also represent the locations of openin~s and possible protrusions, respectively in ~ne of the reverse masks and the con~erse on the other reverse mask of the pair. Again, a protrusion typically but not necessarily isloca~ed opposite each cell end not to be filled. Each reverse mask is fitted to an end face by approximately centering the mask against the end face (i.e. positioning the mask with its axial center within the confines of the central cell 329 or sufficiently near to the central cell so that the axial center of the mask is prevented from aligning over any cell other than the central cell 329 due to the thickness of the protrusions) and vibrating the mask into alignment. Again, means such as the collar 324 (see Fig. 18~ are preferably provided to assure that the axial center of the mask aligns over the center cell 329. This area within which the axial center of the mask is initially posi~ioned and later con~ined during alignment is centered at the center of the central cell 329, andr in the case o~ the uniformly sized cells 316 depicted, can have a maximum diameter at least as great as a cell pitch (i.e. the distance between the centers o adjoining cells in a row or column), and may have a some-what greater diameter, depending upon the diameters of the protrusions at their tips, but in no event will the maximum diameter be as great as twice the magnitude of a cell pitch as this would allow the mask to center over a cell other than the central cell 329. Each o the reverse masks will align opposite the center cell 329 in one of four possible angular orientations separated by 90. On the mask having its protrusion locations represented by "X's 1l, apart from the protrusion which may be proYided to engage the central cell 329, the four protrusion locations closest to the axial center of thP
mask will always align in those four cells lying along the ;33~

diagonal lines at b, c, and d and the mask will al~ays expose the same subset of cells indicated by the "o's".
Similarly, the our protrusion locations closest to the axial center of the remaining re~erse mask (represented in Fig. 22 by the "O's" about the central cell 329~ will always align only in the cells lying along the vertical and horizontal lines e, f, g and h and expose only the cells identified by "X's". I~t will be noted that in this embodiment, the positions o~ the plugged cells at the end faces of the filter bod~ are not congruently spaced when measured from the center o~ the central cell at each of the end faces~ Similarl~, the openings 314 in each of the reverse ~asks will not be congruently spaced between the masks when measured with respect to their axial centers.
Two other embodiments are depicted with respect to Figs. 23 and 24 and utilize a pair of identical masks with a honeycomb structure having the axial centers of its end faces in a thin wall between cells. The honey-comb structure 310 may again be provided circular end faces 312 and 313, the axial centers of which are located in the center of or near the center of a thin wall 317-in one embodiment at or near the mid point of a length of wall between adjoining cells 316, as indicated by the pOillt 330 in Fig. 23, and in another embodiment at or near the intersection of a pair of thin walls, as indicated by the point 331 at the intersection of the thin walls numbered 317 and 332 in the same figure. A pair of identical circular masks are used, again having openings 314 and protrusion locations 315 alternated in row~ and columns as indicated in ~ig. 24 corresponding to the rows and columns of cells o~ ~ig. 23. Their axial centers lie, in the irst embodLment, bPtween an opening location and an adjoining pro~rusion location as represented by the point333 (when used with end ~aces centared at the point 330~, and, in the second embodimentl between four ad-joining opening and protrusion locations as represented ~33~

by the point 334 (w-hen used wlth end ~aces centered at point 331~, as depicted in ~ig. 24. A mask having its axial center at th~ point333 when aligned on the end faces 312 and 313 with that point o~er the point 330 will lie in one o~ two orientations 180~ apar~. Each orientation will expose a dif~erent subset of cells indicated by the "X's'l and "O's", respectively, in Fig.
23. A mask having its axial center at the point 334 when aligned on an end face 312 or 313 with that point over the point 331 will lie in one o~ four orientations 90 apart. Each orientation will again expose one of the two subsets of cells indicated by the "X's" and "O's"
in Fig. 23, the subsets of cells exposed by adjoining orientations (i.e. those separated by 90) being different while those exposed by opposite orientations (i.e. separate by 180~ being the same. In either case, alignment of the mask and end face axial centers can again be achieved by approximately centerin~ the mask against the end face (i.e. positioning it with its axial c~nter within an area centered about the axial center of the end face and sufficiently small so that the mask will only align with its axial center opposing that of the end face) and vibrating it in~o alignment while its axial center remains in that area. Again, this area will have a ~S diameter somewhat less than twice the magnitude of the cell pitch, depending upon the tip diameters of the protxusions, but may always be as great as one cell pitch in magnitude regardless of the protrusion tip diameter.
It is envisioned that in some applications, it will be found that the masks may be approximately centered in selected initial angular orientations on the end face and vibrated into alignment in a preselected relative angular relationship. Alternatively9 the proper relative angular orientation of the identical masks would be verified in some automatic ~ashion to assure that when desired, different subsets of cells are exposed at each of the end aces in the honeyco~b structure for plugging. One way would be to mark each mask in some ~ay, say at a p~int on its periphery, so that the relative angular orientation of the two masks can be compared by suitable sensing equipment and circuitry to signal that desired relati~e angular alignment is achieved. Another way would be to optically ~iew either end face of a structure having a pair of masks fitted or a structure having cells plugged at one end face and a ~ask fitted to its remaining end face to ascertain if light is passing through the structure be~ween ~he end faces. Appropriately aligned ~asks should allow no light to pass through the structure in the area where cells are to be alternately plugged. An appropriate signal can be generated to indicate proper alignment is achieved and that the structure is ready for plugging or that alig~ment was not achieved.
It is further envisioned that where elastic masks are being automatically fitted to honeycomb structures, it may be necessary to provide means to press the mask against the end face to assure complete insertion of the elastic protrusions.
Although the invention has been described with respect to aligning circular masks to circular end faces and square cell cross-sections, it is envisioned that the invention may be successully employed with other end ~ace and cellular geometries. Other desirable end face geometries may include oval and race-track configurations.
Cellular geometries can be circular, oval or any suitable polygon shape, including triangle, hexagon, and any quadralateral. A corral, if provided in such cases, may be circular allowing 360 rotation of the body about the surface. In such cases, the axial center of the mask and end ~ace will lie at the center o thP smallest circular area in which the body or end face may be axially rotated 360, typically the midpoint of the longest transverse axis across the ~ask or end ace Ce.g. the diagonal o 3~

a s~uare or rectangular end ~ace). ~lternatively, a non-circular corral may be used to lImit the range o~
angular motion o~ a noncircular mask so as to assure alignment in a particular or one of a limited number of angular orientations.
It is also envisioned that a corral, if provided, need not be affixed to the honeycomb structure as previously described, but may alternatively be affixed to some other stationary object ox even affixed to -the vibration source.
Moreover, it is envisioned that in some applications lateral and/or angular alignment may he assisted by the use of unusually sized and/or shaped cells and protrusions provided at discrete locations on the body and surface to more particularly limit the lateral and/or angular orientation in which the body may align on the surface.
It is also envisioned that means other than a corral around the periphery of the mask (or honeycomb structure~ may be used to limit the relative lateral and, if desired, rotational motion between the body carrying the protrusions in the honeycomb surface. For example, a rigid member such as a pin or similar means may be passed through and between a mask and an end face of a 2S honeycomb structure as fixing their relative lateral positions during the vibrating step. In one embodiment depicted in Fig. 25, a member 340 has been inserted through an opening 341 at the axial center of a first reverse mask 311. The mask 311 with member 340 is positioned against an end face 312 of the structure 310 as indicated by the arrows 342 ~ith the member 340 extending into the central cell 329 of the end face 312 The mask 311 is then Yibrated into alignmentD In this con~iguration, the mask 311 is ~ree to rotate but is constrained in the lateral mo~ement of its axial center.
The member 340 may then be removed through ~he mask 311 ~3~

and cement pressed through the opening 341 into the proximal end of the central cell 329 during the plugging step~ In a second em~odiment, a 501 id rod 343 or the li~e may be passed khrou~h the length of a central cell 329 of a honeycomb structure, as indicated in ~igs. 26 and 26a. In ~ig. 26, the rod 343 extends ~rom the central cell 32q at a first end ~ace 312 of the struc~ure 310. A first reverse mask 311 similar to that in Fig.
25 and having a similar opening 341 at its axial center is positioned with the rod 343 through the opening 341 and vibrated into alignment. The structure 310 is then inverted, as indicated in Fig. 26a, with the rod 343 protruding from the remaining end face 313 of the structure 310. The remaining mask 311a of the pair of reversed masks, which is also pro~ided with an opening 341a at its axial center, is placed over the rod 343 and against the end face 313 and vibrated into alignment.
The rod 343 is then removed ~rom the structure for plugging of the alternate cells at its ~wo end faces 312 and 313 through the masks 311 and 311a. The opening 341 or 341a at the axial center of the one reverse mask 311 or 311a that corresponds to a protrusion location in the plugging pattern of that mask is temporarily capped to prevent the plugging of that end of the central cell 329. It is further envisioned that two or more rigid me~bers 344, as depicted in Fig. 27, may be provided between an end face 312 of a honeycomb structure 310 and mask 311 to curtail relative rotational as well as relative lateral movement between the mask 311 and the end face 312. The members 344 may be inserted into any two of the openings 345 of ~he mask and the members 344 inserted into the proper corresponding cells at the end face 312. The pro~rusion 315 of the mask 311 may then be vibrated into engagement.
Lastly, relative movement between a first body ~ember and a second honeycomb sur~ace member need not :a2a~

be re~tricted by a means extending between the two members but rather may be restricted by means, again such as a pin, extending between one ~f the two me~bers and a ~ixed o~ject. ~or example, a pin may be provided protruding from the upstream face of the ~ask and the lateral motion of the mask restricted by fixed means such as a tube fixed in a frame which accepts and restricts the movement of the pin protruding from the mask to the inner diameter of the tube.
While fundamen~al novel features of the invention have been shown and described with respect to a preferred and other embodiments, it will be understood that various omissions, substitutions and changes in the form and details of the methods and apparatus heretofore described may be made by those skilled in the art without departing from the scope of the invention which is set forth in the following claims.

Claims (22)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of fitting a first member having a plurality of protrusions extending therefrom to a second member having a honeycomb surface with a multiplicity of openings extending therethrough, said protrusions engaging selected ones of said openings when said first member is fitted to said second member, comprising the steps of:
positioning said first member and said protrusions against said surface; and vibrating at least one member until said protrusions protrusions engage said selected openings.

2. The method of claim 1 wherein said step of positioning further comprises approximately centering said first member against said surface.

3. The method of claim 1 further comprising during said vibrating step, the step of rotating said members with respect to one another.

4. The method of claim 1 wherein said step of vibrating comprises rotationally vibrating at least one of said two members.

5. The method of claim 4 wherein both members are rotationally vibrated during said vibrating step.

6. The method of claim 1 further comprising the step of limiting the relative lateral movement between said two members during said vibrating step.

7. The method of claim 1 wherein said step of vibrating further comprises vibrating said members at a frequency of approximately thirty cycles per second or more.

8. A method of fabricating a solid particulate filter body comprising the steps of:
providing a honeycomb structure having a multiplicity of hollow cells extending through the structure and through a pair of end faces of the structure, said end faces being substantially identical and formed by a matrix of porous intersecting walls also extending therebetween and therethrough;
providing a pair of masks, each mask having a pair of opposing faces, a plurality of openings extending between and through said opposing faces and a plurality of protrusions extending from one opposing face;
approximately centering one mask with one end face; and vibrating said one mask into alignment against said one end face with its openings exposing a first subset of cells and its plurality of protrusions engaging an equal plurality of the remaining cells.

9. The method of claim 8 further comprising the steps of:
approximately centering the remaining mask with the remaining end face; and vibrating said remaining mask into alignment against said remaining end face with its openings exposing substantially all of said remaining cells and its protrusions engaging an equal plurality of said first subset of cells.

10. The method of claim 8 wherein said step of providing a honeycomb structure further comprises providing said structure with the axial centers of each of said two end faces within the open transverse cross-sectional area of one cell, and said step of providing a pair of masks further comprises providing one mask the openings of which exposes one subset of cells and a second mask the openings of which exposes substantially all of the remaining cells of the multiplicity when either mask is fitted to one of the end faces with its axial center opposite said one cell.

11. The method of claim 10 further comprising during said vibrating step to step of restricting the lateral movement of the axial center of said one mask to substantially the transverse cross-sectional area of said one cell.

12. The method of claim 8 wherein said step of providing a honeycomb structure further comprises providing said structure with the axial centers of its two end faces extending through a thin wall between cells and said step of providing a pair of masks further comprises spacing the openings through each mask substantially identically from the axial centers of each mask.

13. The method of claim 12 further comprising during said vibrating step the step of restricting the lateral movement of the axial center of the one mask to an area centered on said thin wall and approximately equal to the area of one cell adjoining the wall.

14. The method of claim 8 wherein said vibrating step comprises orbitally vibrating the mask with respect to the end face.

15. The method of claim 14 wherein said vibrating step further comprises orbitally vibrating the structure.

16. A combination comprising:
a honeycomb structure having a pair of opposing end faces and a multiplicity of cells formed by thin walls extending through and between said end faces;
a body having a plurality of protrusions extending therefrom, and being positioned with its protrusions against one end face of said honeycomb structure;
means for limiting lateral motion of said body across said end face; and means for vibrating said body with respect to said one end face.

17. The combination of claim 16 wherein said means for limiting further comprise corral means positioned around the periphery of said body.

18. The combination of claim 16 wherein said means for limiting further comprises a member extending between and into said body and said one end face.

19. The combination of claim 16 wherein said vibrating means further comprises means for rotationally vibrating said body with respect to said one end face.

20. The combination of claim 16 wherein each end face of said honeycomb structure has an axial center located within the same one cell, said body has an axial center and further comprises a plurality of openings extending therethrough which expose a first subset of said cells when the body is aligned with its axial center opposite said one cell, and the combination further comprising:
a second body centered over the remaining end face of the structure and having a plurality of protrusions extending therefrom and a plurality of openings extending therethrough exposing a substantially different subset of said cells, the distances of the openings and protrusions of the second body from the axial center of the second body being substantially the same as the distances of the protrusions and openings, respectively, of the first body from the axial center of the first body.

21. The combination of claim 16 wherein each end face of said honeycomb structure has an axial center located within the same thin wall, said body has an axial center and further comprises a plurality of openings extending therethrough which expose a first subset of said cells when the body is aligned with its axial center opposite an axial center of one of said end faces, and the combination further comprising:
a second body having an axial center, a plurality of protrusions and a plurality of openings spaced from the axial center of said second body the same distances as the openings of said first body are spaced from the said axial center of said first body and fitted to the remaining end face of the structure with axial center of said second body opposite the axial center of said remaining end face, and the openings of said second body extending therethrough exposing a substantially different subset of cells.

22. The combination of claim 21 further comprising:
means for generating a signal indicating that substantially different subsets of said cells are exposed by the openings of said first and second bodies.