US 3095619 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
July 2, 1963 E. F. PETERSON 3,095,619
METHOD AND ME FOR SEALING ADJACENT COACT G CLOSURE SURFAC OF CAVITY CONTOURING STRUC ES Filed Dec.- 16, 1958 5 Sheets-Sheet 1 fgp j. 42
F 1 X i IN VEN TOR.
Fin Jim FPei'ewso-m July 2, 1963 E. F. PETERSON 3,095,619
METHOD AND MEANS FOR SEALING ADJACENT COACTING CLOSURE SUR 8 Filed Dec; 16, 195
FACES OF CAVITY CONTOURING STRUCTURE? ets-Sheet 2 & V/A
\ gmoo HVVENTOR:
July 2, 1963 v E. F. PETERS 3,095,619
METHOD AND M NS FOR SEALING ADJA E T COACTING CLOSURE SURF s OF CAVITY CONTOURING STRUC ES Filed Dec. 16, 1958 Sheets-Sheet :5
' 342 //4\ *3, INVENTOR: 32 35 fiagzjnfff iefison 3,095,619 OSURE E. F. PETERS FOR SEALI July 2, 1963 ON ADJACENT COACTING CL NTOURING STRUCTURES 5 Sheets-Sheet 4 METHOD AND MEANS SURFACES OF CAVITY Filed Dec. 16, 1958 s 'm 50%3? L INVENTOR:
July 2, 1963 E. F. PETERSON METHOD AND MEANS FOR SEALIN sum Filed Dec. 16, 1958 3,095,619 G ADJACENT COACTING SURE ACES OF CAVITY CONTOURING STRUCTURE Sheets-Sheet 5 /aa' m4 gws INVENTOR: E d wan ff icnson United States Patent 3,095,619 METHOD AND MEANS FOR SEALING ADJACENT COACTING CLOSURE SURFACES F CAVITY CONTOURING STRUCTURES Edwin F. Peterson, P.0. Box 151, Neponset, Ill. Filed Dec. 16, 1958, Ser. No. 780,775
40 Claims. (Cl. 22-10) This invention is directed to the method of providing a positive air seal between coactin-g surface areas that normally lie in abutting relation to form the usual closure means between coacting sections of a composite unit which provides the contour forming means of a confined cavity subjected to pressure and lying within said unit. Obviously a selected pressure differential prevails under operative conditions between the cavity space and the ambient atmosphere surrounding such a composite unit. Without proper sealing means supplementing the normal closure surface areas, air leaks occur under many conditions of use and such leaks are detrimental to the efiicient and continued elfec tive operation of such described composite cavitated units.
More specifically, this invention rel-ates to the sealing of the complementary parts of core forming boxes and molding equipment such as pressure molds, blow plates, mating flasks and to anyequivalent analogous boxes or mold units that require internal pressurized cycleconditions for their successful and intended functions.
For one example, core forming boxes are used in foundry practice that may be simple or very intricate in design and construction. Blowing sand cores with air under pressure to force oore sand into the box cavitiescreates many wear problems which reduce the normal life of such boxes. A condition similar to wire drawing in high pressure valve seats is developed through leakage of sand and air along parting lines of the composite sections of the core box. Once leakage and wear of this character begins, the box is soon rendered inoperative for use. It must be taken out of service and repaired or discarded.
"Such parting line leakage may be the result of poor handling, the accumulation of sand and/ or other foreign particles that build up or become lodged upon either of the mating surface areas, or by the development of damaged or cracked surface areas.
An object of this invention is to provide sealing means which will reduce the above mentioned foundry equipment failures to a minimum-thus protecting the equipment from early repair or discard and extending the useful life thereof. i
A further object is to provide a dual coacting and mating sealing instrumentality for core boxes and. the like.
Another object relates to the method and means herein disclosed in creating the eifective sealing means for mating members of cavitated assemblies to counteract bypass of fluid and/or'sand from within such assemblies atthe parting line surfaces thereof.
Another object is to provide coacting sealing means associated with the matching or mating sections of foundry equipment such as core boxes whereby the sealing means are made as extruded continuous resilient oil and abrasion resistant strips that possess configurations directly contributing to their installations and to their successful sealing function. Such strips further provide continuous effective seal means under various conditions of use and also introduce features that act to overcome certain deficiencies of core box design as well as certain developed faults directly contribut-able' to manual over sight or carelessness of the foundry workman.
There are further objects inherent in the design of the sealing means of this invention which relate, for example, to the novel end joining means employed for connecting 3,095,619 Patented July 2, 1963 the strip ends at their meeting point after encircling a core box cavity; the unique manner of anchoring the strips in the surface areas of the box sections; the use of a putfable or expansible material to carry out the method of providing a positioning and retaining means to place the seal strip per se; and to the effective seal function inherent in the shape of the sealing units in cooperation with their receiving recesses in the parting faces of the box sections wherein each seal strip also seals the puifable material within the holding cavity or strip recess for purposes to be explained.
All other objects and advantages relating to the sealing means of the present invention shall hereinafter appear in or become apparent from the following detailed description having reference to the several embodiments of the invention that are illustrated in the accompanying drawings and which form a part of this specification.
In the drawings:
FIG. 1 is a vertical cross sectional view of a two piece core box as it appears inits normal operative state and ready for core blowing through one or more suitable core sand entry apertures or the like;
FIG. 2 is a face view of the cavity side of one of the core box sections illustrating a step in the method of preparing this box section for the reception of a sealin-g strip as herein disclosed;
FIG. 3 is a fragmentary "ertical cross sectional view to show the created strip recess or slot as it appears when seen along the plane of the line 33 in FIG. 2;
FIG. 4 illustrates a fragmentary cross sectional view similar to FIG. 3 with an additional undercut provided in the cross sectional contour of the strip receiving recess or slot; 7 I
FIG. 5 is a fragmentary cross sectional view of the strip inserting step including the puff-able material insertion and the general closure of the recess by the mating box section all contributing to the application of one of the sealing strips to one box section;
FIG. 6 shows the relationship of the sealing strip in FIG. 5 under completely installed conditions;
FIG. 7 is a fragmentary perspective view of the ex truded sealing strip displayed in FIGS. 5 and 6 and as it appears prior to in-s'tallation;
FIG. 8*shows the manner of providing a visual layout pattern on the mating core box section to produce a guide means to mil-1 out or to otherwise provide the second core box section with a recessed trough or slot to receive a coacting sealing strip that will cooperate with the sealing arrangement of the first box section;
FIG. 9 illustrates the created guide pattern as it appears on a segmental part of the section core box section after the FIG. 8 treatment;
FIG. :10 shows a composite arrangement of both core box sections as they will appear in the cycle of the method described that orients thesecond coacting sealing strip into the strip carrying recess or slot of the second box section;
FIG. 1'1 shows a fragmentary perspective view of a portion ofthe second strip as it appears in its extruded form prior to installation;
FIG. 12 is a cross sectional view of the completed dual assembly showing the two strip units in their re-. spective final positions as they appear after the completion of the method steps from FIG. 10 and likewise as these parts coact in sealing relation under operative engagement of the adjacent sections incorporating the sealing structure; J
FIG. 13 is a perspective view of the end of the deformable apertured strip of FIG. 11 to illustrate one arrangement for joining strip ends;
FIG. 14 illustrates, in section, the sealing action that 3 results between the two coacting strip members under lateral misalignment conditions;
FIG. represents another condition where sealing is accomplished with the normal sealing surfaces of the parts not entirely disposed in face to face and abutting contact;
FIG. 16 illustrates a side elevational view of a closed core box wherein the companion sections are somewhat out of true or warped causing slightly separated areas between the parting line faces and wherein the dual sealing means supplies the necessary stop gap at the open face areas to overcome the deficiency rendering the core box operative for normal core blowing use;
FIG. 17 is a cross sectional view taken in the plane of line 17-17 in FIG. 16 to illustrate the installation and relationship of the sealing units at the faulty areas;
FIG. 18 is a sectional detail view of a modified arrangement of strip with particular reference to a novel condition produced by anchor sealing leg portions of the strip sides pressed against the side walls of the groove or slot.
FIG. 19 is a cross sectional detailed view of an insert strip incorporating a self-contained pufrable material to provide a composite installation unit;
FIG. 20 is a perspective view of a companion seal strip for the design of strip shown in FIG. 19;
FIG. 21 is another cross sectional view of a modified seal strip employing a compressed soft wood strip or liner as the pulfable material;
FIG. 22 is a perspective view of the wooden insert unit associated with the strip assembly in FIG. 21 to better illustrate certain constructional details thereof;
FIG. 23 shows a sectional view of a sealing assembly that provides another modified composite seal strip;
FIG. 24 illustrates another form of strip embodying a pulfable material comprising compressed foamed epoxy resin;
FIG. 25 illustrates a fragmentary cross sectional portion of a core box providing a slot in the parting surface thereof having a modified shape for the undercut parts thereof;
FIG. 26 shows a perspective view of a portion of an insert strip with puffable material specifically devised for use in the slot shown in FIG. 25;
FIG. 27 is a sectional view showing the strip seated within the slot and prior to activation of the pufiable material carried by the strip;
FIG. 28 shows the strip under activation and hemmed in by means of a suitable slot cover, the strip here assuming its attached relation within its slot and as finally oriented for operative use;
FIG. 29 is a perspective view of a companion strip that carries its putfable material and which is designed for attachment within a slot in a mating core box section to provide sealing coaction with the strip of FIG. 26;
FIG. 30 is a perspective view of a strip similar to that of FIG. 26, but showing access openings in the strip for moisture or fluid ingress to the puffable material of the strip; and
FIG. 31 is a diagrammatic view of an assembled core box with one section being subjected to cooling while the other section is being heated by a torch or other heat source in the practice of the method disclosed herein.
In order to simplify the description of the invention and of the respective features inherent in the sealing means herein developed, FIG. 1 shows a simple two part separable core box having similar mating sections '1 and 2 provided with cooperative matching cavities 3 and 4, such sections abutting each other along coacting surfaces 5 and 6 that provide normal conventional sealing areas to isolate the internally formed cavity from the box exterior. Suitable orientation socket and pin means 5a are provided to align and to orient the box sections for true matching of the mating cavity portions as is well understood by those skilled in the art. p
The method of providing the core box with the sealing means herein disclosed includes a step as shown in FIG.
2 which comprises cutting a continuous slot or groove 7 with a milling tool M directed in a given relation about the cavity location and into the surface area or face 5 of section 1. FIG. 3 shows slot 7 in section and in the general relation occupied thereby with reference to the surrounding adjacent body structure of the box section 1.
A further step involves the use of a suitable milling tool or cutter similar to a Woodruff key cutter to provide lateral undercuts 8 and 8a along the base of the slot 7 as shown in FIG. 4. Conceivably, other suitable special tools may be employed to cut a slot or groove of the cross sectional outline indicated in FIG. 4.
While the description will continue at this stage with reference to the method employed to complete the details of the strip installation, an intermediate slot orientation step is necessary at this point to mark the companion core box section for its companion slot location. With the section 1 supplied with either slot 7 as in FIG. 3, or with slot 7 undercut as in FIG. 4, the FIG. 8 step is normally practiced at this time prior to the permanent insertion of a strip into slot 7 as will hereinafter clearly become apparent from the related description directed to the FIG. 8 procedure.
Continuing now with the method of strip insertion, the procedure includes the partial filing of slot 7 with a puffable material 1011 of a composition or nature that will expand under activation with a suitable catalyst and retain its shape after expansion. While various kinds of analogous substances may be employed to perform in the manner herein contemplated, several preferred materials have proven successful and effective to carry out the process under the concept of the present invention.
One such composition is readily obtainable on the market under the name polyisocyanate, a product prOcessed and sold by the Minnesota Mining & Manufacturing Co. An analogous composition for the use herein contemplated is sold under the name polyurethane. The ingredients for this material are made by the Allied Chemical Corporation. The compositions noted are considered synonymous in character.
-Both of these materials are normally dormant and resemble very viscous fluids which, with the addition of suitable catalyst supplied by the companies named, will become activated and begin to expand under normal room temperature conditions and will set and cure in expanded relation. They are, therefore, considered as cold process mediums that are directly suitable for the method used to orient and to retain the sealing strips in place Within the milled slots provided in the opposed face surfaces of the core box sections. It is understood that the curing cycle may be accelerated by the addition of heat that may be supplied by immersion of the joined core box sections in hot water.
Minnesota Mining & Manufacturing Company produces a Scotch foam Brand Expansible Compound, Type 1, that provides a foamed-in-place, self-curing, low density polyisocyanate foam compound having a toluene diisocyanate base. The catalyst including an organic amine for the Type 1 composition is identified as Scotch foam Catalyst 1-020 that is added in the proportion of 7.3 parts to parts of the Type 1 material.
Some of the other companies that manufacture these foaming or analogous compounds are Atlas Mineral Products Co., Mertztown, Pa.; Dayton Rubber Co., Dayton, Ohio; Emerson and Cumming, Inc., 869 Washington St., Canton, Mass; Mobay Chemical Co., 1700 S. Second St., St. Louis 4, Mo.; and Nopco Chemical Co., First and Essex Streets, Harrison, N.J.; and D & R Pilot Plants, Inc., Hazardville, Conn.
These materials also possess a further capability that is considered quite significant to the resultant sealing means of the core box parts. The compositions expand to a considerable degree, if freely permitted, and then they assume a rigid dense and stable condition in which state they cure or compact so as to set into the allotted expansion area that was provided for such expansion. Then they so remain without further change inshape or consistency to completely fill the alloted space or cavity holding such materials.
One other very inherent advantage was discovered in using materials of the class described. Such benefit lies in the latitude of use of the puifable substance and in the variation of the amounts that may be employed in the slot or grooved considered. The amount of substance used will be gauged by the amount required to fill the allowable expansion space that is provided and a suggested normal average amount may be better contemplated from the following descriptive matter.
While the cold expansible compositions are very efiiciently applicable in practicing the method of this invention, certain other substances having the characteristic phenomenon of expansibility activated by catalytic action or through other mediums may be employed to addi tionally react under conditions including low heat application should that be desirable. For example, some of these substances are compressed soft wood rendered expansible by water and compressed foamed epoxy resins rendered expansible through heat.
Continuing now with the detailed description of the invention, the method further contemplates the placing of a resilient seal strip 9 of extruded rubber or rubber-like material into the slot 7 into a position located beneath the mouth or entrance area of the slot and in the direct physical contact with the puffable material in a manner as best shown in FIG. 5. It has been contemplated and experienced that the maximum amount of viscous fluid puffable substance to introduce into the slot can be well gauged through the placement of the strip. The strip should be placed to a depressed level in the slot to provide a reasonably adequate clearance space above the strip to permit the desired planned swelling action of the puifable material to take place.
With this predetermined clearance space established over or above the strip seated in the slot as explained, the necessary planned action can be readily carried out to orieat the strip into a retained position and in a location to function in the operative sealing capacity contemplated.
The strip 9 is preferably extruded high acrylonitrile Buna N rubber which is made in a shape that is designed to conform to a definite cross sectional area to accomplish a number of well considered functions directly contributing to the provision of the effective seal herein contemplated. As shown in FIG. 7, strip 9 has a body or sealing head that is generally rectangular in cross section bordered by upper coplanar surfaces or facs 11 and 12, a bottom face 14 and side edges 11a and 12a. The upper surface includes the semicircular groove 13 separating faces 11 and 12, while the bottom of the strip 9 is provided with one or more projecting anchoring devices in the form of depending legs or beads 15 and 16 extending downwardly from the bottom face or surface 14 of strip 9. The beads readily penetrate the initially provided puffable substance a that is suitably introduced and held within slot 7. Such material 10a has been already explained as being highly viscous and such substance may be packaged in flexible tube with a suitable discharge spout and orifice whereby to permit easy application of this substance to a desired depth along the bottom of groove 7 also filling the undercut portions 8.
Actually, the core box sections may Well include irregular face to face parting lines that are not necessarily level. But, due to the viscous nature of the puifable substance, this material will not run from the higher elevations to the lower and no problem of application is therefore presented under the conditions noted.
Another important consideration accompanying the strip attachment and orientation in the core box section groove is to produce the strip in a width so that the side edges He and 12e are snuggly in contact with the opposite walls oversize of strip width is contemplated substantially on the order of 0.010 inch per inch of strip width to cause dual sealing contacts between the adjacent strip sides and groove side wall surfaces as cooperatively paired by the reference numerals 11e--11w and 12e12w indicating the related wall sealing portions. The object is to seal in the puifable material into the slot beneath the strip per se and to thus hold this composition in a scheduled and confined space considered inaccessible from the entrance mouth of the slot or groove 7.
The reason for this arrangement is to prevent deterioration or possible damage to the puflfable material that may be adapted for the purposes indicated. While the polyisocyanate and polyurethane substances are not normally susceptible to attack or deterioration by the usual fluids or liquids used about a foundry or core shop to treat, clean or otherwise carry out the various phases that accompany core making on a commercial basis, there are other pulfable materials that can be used which do not have the resistance or chemical character to withstand all such foundry fluids. Thus, with this added insurance of trapping or isolating by the wall to wall edge contact described, an additional advantage results that permits the wider use of analogous materials having the nature described, such as compressed wood for example.
With the above thoughts in mind and now with reference to FIG. 5, the core box section has now been provided with the chemical 10a in the groove bottom followed by the insertion of strip 9, and the other core box section 2 is placed in registry upon section 1 to form the closure wall portion for the groove 7 month or entrance way. This then provides a relationship of the parts that permits theexpansion of the material 10a to move the strip 9 upwardly in slot 7 until the coplanar top faces 11 and 12 engage the surface 6 of core box section 2 to be halted in this relation with the material 10a then completely filling the developed cavity space under the strip 9. The substance 10a fills out the entire available groove or slot 7, the undercut areas and the hollow T-shaped areas between and to either side of the respective strip beads 15 and 16.
After the activated cycle condition subsides, the original material 10a then solidifies and cures into a noncompressible mass and to a stable rigid substance 10b. Removal of section 2 from its'contact with section 1 as in FIG. 5 will now leave section 1 equipped with the strip 9 lodged in the secured relation best illustrated in FIG. 6. This arrangement forms the one part structure of the dual sealing means herein devised to carry out the present method and to provide one preferred means for sealing any one of the various instrumentalities noted.
The method for providing a second coacting sealing means is carried out much the same as above described in detail. 'For purposes of further explanation, the one omitted step in the process previously mentioned includes the marking of the second core box section 2 for purposes of duplicating the location of the groove or slot means 7 in section 1. Obviously this is necessary to locate both sealing assemblies in proper alignment in the two core box parts for direct operative juxtaposition.
This orientation step is accomplished and better understood by referring back to FIGS. 3 and 4. With the groove 7 milled or otherwise cut into section 1, either as a slot 7 like in FIG. 3, or as the undercut slot portions 8 and 8a in FIG. 4, a band Bof stable nonporous but relatively flexible material is placed in the milled slot 7 of section 1 to protrude as shown. Then the sections 1 and 2 are oriented by their pin and hole means 511 for true matching alignment with the band B resting upon face 6 of section 2. If desirable, suitable clamp means C may be used to prevent separation of the sections during the 11w and 12w of the groove or slot 7. In fact, a slight 76 completion of the marking step.
With the two sections in position and held under separation by the band B, a brush applicator A may then be used to spread any suitable kind of dye material or layout blue upon that portion of the surface 6 of section 2 that lies radially outwardly of the abutted band B location. Separation of the core box parts will now provide section 2 with a colored or painted area P as shown in FIG. 9. The use of the cutter or milling tool M can now be guided along the edge of the marked area to provide a groove or slot 17 duplicating slot 7 and following the exact path of slot 7 thus providing matching slots in sections 1 and 2 to receive the coacting sealing means respectively.
The second sealing means is then placed into slot 17 in the form of the pulfable viscous material 100 as in FIG. 10 followed by the extruded strip 18 of rubber or rubber-like material. The strip 18 is designed for direct sealing coaction with the strip 9 by providing such a strip 18 with a special cross sectional design. This design includes coplanar top surfaces 19 and 20 that are arranged for direct coplanar alignment with the parting surface 6 of section 2. However, under the orientation and securing process with respect to strip 18, the latter is first placed with the faces 19 and 20 located beneath the face surface 6 of section 2 as shown in FIG. 10 subject to the pulfable expansion of the material 10c. Such expansion with the final orientation of strip 18 is governed by the use of the finished assembly of section 1 and its strip 9 which is placed over section 2 in FIG. 10 to predetermine the limits of action or movement of strip 18 within slot 17 during the expansion of material 100.
The final relationship of the respective strip means is best illustrated in FIG. 12 and this is the general sealing cooperation that prevails between the dual seal units at any time during subsequent use whenever sections 1 and 2 are operatively seated with the parting line surfaces and 6 in contact.
The second described seal strip 18 is best shown in FIG. 11 and comprises a generally rectangular body defined by the top coplanar faces 19 and 20, the bottom face or surface 23, and the side edges 19:: and 20e. A ridge or seal protuberance 21 projects above the surface planes of the top faces 19 and 20 to provide a pressure contact seal structure for reception by the groove 13 in seal strip 9. The exterior of ridge 21 is shaped in the outline of a gothic arch form to provide a high point for initial contact with the bottom of groove 13 and to provide the added facility of being compressible or flattenable under additional seal strip union to cause the gothic arch ridge to flatten out into the groove 13 into a shape such as generally shown in FIG. 12.
To aid in the distortional sealing qualities of the gothic arch seal protuberance 21, strip 18 is made with a continuous aperture or opening 22 following the length of the strip. This opening 22 is located at such a point as to establish thin walls 26 and 27 near to the top faces 19 and 20 of the body of the strip and to promote greater lateral flexibility of the entire gothic ridge structure 21 to carry out its intended sealing function.
As further seen in FIG. 11, the strip 18 has one or more legs or anchor members such as the depending beads 24 and 25 that extend along the underside of the strip body. As in the first described strip 9, the opposite outward sides 19c and 20e of strip 18 are located to provide contact seal means with the corresponding walls 19w and 20w of slot 17.
In applying a strip such as 9 to a core box section, the strip is made to follow the contour of the box groove. Preferably, one joint will be necessary although more than one joint is also feasible in strip installation. However, the two strip ends are square cut and slightly long on the order of .002 to .003 of an inch per inch of total length. The excess length insures good longitudinal abutting contact of the strip ends to eliminate the possibility of having a space between the adjacent strip ends. Perfect alignment of the ends within the slot results by the use of material a that orients and secures strip 9 in place 8 in the slot provided in the corresponding core box section.
In the case of the strip 18, which is subjected to greater movement and sealing activity, a flexible tubular member T is employed to connect the adjacent end parts of the strip. The strip length is cut to abut the ends as in the case of strip 9, but the tubular member T can then be inserted in one strip end to receive the second strip end. With the depression of both strip ends into the allotted receiving groove, the ends will come into contacting engagement while including the inserted tubular member. Member T will not interfere with the sealing action of the gothic ridge by reason of its flexible tubular form.
Under operative conditions, any slight lateral displacement between core box sections will be taken up or adjusted for by the gothic ridge within the groove of the mating strip as shown in FIG. 14. This action is primarily due to the provision of the thin walls 26 and 27 of the ridge 21.
Even under the most favorable conditions, it is possible for sand, dirt or other foreign material to collect or to pile up in certain areas of the parting surfaces of core box sections as illustrated in FIG. 15. When this occurs, the gothic ridge will still seal into the groove of the companion strip. However, while some added clearance may be developed between the sides of the ridge 21 and the groove 13, any fluid pressure exerted against the ridge from the box cavity location will tend to flex the ridge bodily against the opposite groove side to greatly extend the sealing contact area between the described parts.
The sealing means of the present design are also inherently advantageous when being installed into core box sections that are not entirely perfect in their parting line contact. This condition is shown in FIGS. 16 and 17. In such instances, the installation of the first seal strip 9 by the method used will cause the strip to move out of the groove 7 into surface contact with the mating core box section by the amounts 28 and 29 to span the gap 30 that prevails between surfaces 5a and 6a of the core box sections 1a and 2a. Obviously, the installation of the second seal strip 18 will easily follow without any change in the method herein developed and described. This illustrates the latitude of installation and the selfadjusting capabilities of the coacting sealing means.
While there are certain variations possible in the described method and means of providing a sealing structure for the purposes intended, FIG. 18 illustrates a modified form wherein a strip 31 is extruded to include half anchor elements or legs 32 and 33 to position flat walls 34 and 35 against the walls 36 and 37 of the groove or slot 38 in a core box section 39. With this arrangement, the pulfable material 40 introduces and develops a lateral pressure against the respective lateral inner surface areas of the elements 32 and 33 to not only additionally hold the strip 31 in place in slot 33, but to also increase the frictional sealing contact of elements 32 and 33 against Walls 36 and 37 of the seal holding slot 38.
In FIG. 18, no undercut slot means are illustrated and the frictional feature discussed will provide sufficient holding power to keep the seal means in its normal seated relation within the slot. Under operative conditions, there will practically be no occasion when any force can act to withdraw a sealing strip from its holding slot. All pressure will be directed upon the strip and in a direction to hold the strip in its corresponding slot.
With this in mind, the holding slots may be cut as in FIGS. 3 and 18 or as in FIG. 4 to include the undercut feature. The undercut slot provides an arrangement to positively retain the puifable holding substances to supplement the frictional holding action of such substances against the slot walls. Other combinations of undercut slots and strip assemblies securable into such slots will be hereinafter described.
With further reference to FIG. 18, it should be observed that the extruded seal strip 31 is provided with hollow portions or apertures 41 and 42 that flank the recessed part 43. With this arrangement additional sealing distortion of strip 31 is also possible under the cooperative action of a projection such as 21, or of other raised means that may be carried by a coacting seal strip under the operative conditions generally described in defining the functions of the two seal strips of this invention.
Attention is further directed to the ease with which a damaged section or portion of one of the seal strips may be replaced. The damaged part can readily be cut out including the removal of the expanded holding material. Then by supplying the slot with some puifable material, introducing a new length of cut to size strip for the gap created, and by closing the core box sections, a quick reinstallation repair job is completed.
The above described forms are of the character wherein the putfable material is separately applied to the groove and the strip is installed over the material.
FIGS. 19 to 23 illustrate other forms and variations of the means that may be used for carrying out the method of seal strip insertion and orientation. The means in these Views are shown to demonstrate articles of manufacture comprising the use of a composite strip of seal material and puffable material. Such an assembled structure is beneficial for quick and efficient installation.
FIGS. 19 and 20 show companion strips 44 and 45, with strip 44 occupying a position in groove or slot 46 of a core box part 47 and with strip 45 appearing in its unattached and useable condition. Both strips 44 and 45 are evolved from the form in FIG. 18, minus the intermediate anchors, but with special flexible leg forms that fulfill dual purposes.
The strip 44 of FIG. 19 comprises a sealing head 48 having a V-shaped slot 49, and having anchoring means in the form of legs'50 and 51 that are angularly carried by the head for contact at 52 to form an enclosure or chamber 53. Each of the legs has an outwardly directed foot 54 and 55 which feet are adapted for entry into undercut recesses or notches 56 and 57 of slot 46, as shown in broken lines in FIG. 19.
Chamber 53 provides the reservoir or retention means to carry an expansible substance which will have the facility to swell or puff out of the chamber 53 into the slot space and to force legs 50 and 51 outwardly against the opposite slot walls with the feet 54 and 55 disposed in the undercut recesses 56 and 57. The puifable material may be, as in the previously described form, a polyisocyanate or. polyurethane substance 58 which, upon expansion under activation, will force strip 44 upwardly against an overlying reference plane or surface 59 acting as a slot cover or control part 60. A compressed epoxy or a ground or granular puffable material may be used in chamber 53 if such is preferred.
To permit complete and uninterrupted elevation of strip 44 in slot 46, the strip side lengths from the top of the strip head 48 to the top of the feet 54 and 55 must be equal to or greater than the slot wall depth from the upper outer surface of the core box part to the top levels of the undercut recesses or notches 56 and 57.
The companion sealing strip 45 in FIG. 20 comprises a sealing head 61 having an upstanding steeple ridge 62 which is hollow due to an aperture 63 that produces two upwardly directed thin side walls 64 and 65. The bottom of the aperture 63 is brought below the sealing level surface 66 of the strip to allow a given amount of partial displacement of adjacent portions of either thin side wall into the sealing head apertured portion of the strip under lateral thrust or side pressure on ridge 62.
Strip 45 is also provided 'With depending legs 67 and 68 having feet 69 and 70 inwardly abutted at 71, to form a cavity or chamber 72 in the strip. Any tubular dispensing means can be used to fill chamber 72 or chamber 53 with an expansible substance by insertion through the contact area 71 or 52 and by drawing the dispensing means along the strip. The legs and feet will automatically close, thus retaining the puffable material within the strip. The strip can then be pushed into its allotted slot with ease. When the material is on the order of polyisocyanate, which is heavy and highly viscous, it does not flow out of the strip ends and is well retained within the strip cavity. If a fluid material of greater flowability is selected, the strip can be closed at either or both ends by suitable plug means to trap the material Within the strip prior to strip application into a strip slot.
FIGS. 21 and 22 illustrate a seal strip 73 having the same extruded cross sectional shape as strip 44, but carrying a putfable material in the form of a wooden strip or liner 74. The wooden strip or liner 74 is preferably made from soft woods such as sugar pine, cork pine, white pine, basswood, balsa and the like. Liner 74 is in the general shape of a trapezium and comprises a hydraulically compressed wooden strip or liner. This developed compressed strip or liner may be formed out of an originally rectangular wooden piece such as shown in broken lines in FIG. 22, and alternate opposite side edge slits 74a and 74b may be provided for flexibility of the strip either laterally 'or vertically.
Liner 74 is slightly oversized to either hold or to spread legs 75 and 76 apart upon insertion to provide an entrance way 77 into the chamber 77a of strip 73 carrying liner 74. With the strip 73 assembled into slot 78 of a core box part 79, suitable access drill holes 80 are used as ports to allow the introduction of a fluid such as water into slot 78 for contact and wetting of the compressed Wooden liner 73. It has been found that water including suitable Wetting agents may be used to speed up the process. The liner will expand under wetted conditions to urge legs 75 and 76 outwardly in-to slot wall contact with their respective feet 75a and 76a disposed with in slot undercuts or recesses 81 and 82. Strip 73 will also be raised and may be oriented as in the previously described forms of the invention.
FIG. 23 illustrates a compressed rectangular block form of liner or insert 83 cemented or otherwise attached in place at 84 to the undersurface 85 of the sealing head 86 of a seal strip 87. In other respects, this arrangement functions like the other analogous forms under the application of water.
In the FIG. 24 illustration, the putfable insert material 88 is made out of a compressed liner of foamed epoxy resin. While the cross sectional shape may be made to assume various designed outlines and body shapes, FIG. 24 illustrates a resin insert 88 that is cemented at 89 to the under surface 90 of a seal strip 91 having the constructional characteristics of the other sealing strips shown in FIGS. 19, 21 and 23.
It has been ascertained that the foamed epoxy resin material can be hydraulically compressed, for example, to one-sixth of its original volume. The resin will retain this compressed shape until the application of heat which will cause the resin to expand again to substantially percent of its original shape and size. The temperature to bring about this reconversion need only be slightly above that of boiling water or in the vicinity of 220 F. and need not exceed temperature of boiling water. Actually a temperature up to 350 F. is not harmful to the use of a compressed epoxy resin.
The 220 F. temperature is considered well below the heat range that Will prevent warping or distortion of the core box material. It is known that both aluminum and magnesium are used for core box metals. Both of these metals are quite sensitive to temperatures exceeding 300* But with the application of low heat for the expansion of a compressed foamed epoxy resin material, no objectionable conditions are created.
In' this same category, installation or replacement of worn ordamaged strips with new strips having the resin 1 1 material expander will also be feasible for any type of core boxes including repaired boxes that contain low melting point solder alloy metals. The low heat required for the resin strip installation will be readily feasible and will not be detrimental to the core boxes that are normally employed in foundry practice.
In order to better understand some of the physical properties of the foamed epoxy resins and their application to the present method of strip installation and strip securement to a piece of foundry equipment, certain general characteristics will now be described. While other manufacturers produce analogous resin materials to that here employed, one particular kind that has been found to be quite suitable is known as DuRafoam made by the D & R Pilot Plants, Inc., of Hazardville, Conn. The material is obtainable in various densities and the one used is a 101-? density for a block of the epoxy resin material equivalent to a cubic foot in quantity.
This resin material can be cut and compressed from a selected oversized piece down to the dimensional shape required for slot insertion. While the foamed epoxy resin has been successfully worked under compression at room temperature, it is recommended that the resin may be heated to 300 F. before compression for consistent thermal conditions. Then also, when the resin is later again activated under a selected heat value in a slot with the seal strip, the expansion puffs the resin into the allotted open space in the slot. It has also been found that the resin material is rendered more consistent if it is allowed to cool to about 100 F. under the dimensional restrain of the slot and slot cover parts before removal of the latter part from its restraining position.
The DuRafoam is not affected by the usual normal climatic changes in temperature, humidity or moisture. It is free from warp. It is dimensionally stable. And it has no grain. The substance is unaffected by solvents.
In general, the DuRafoam epoxy resin provides an ideal puffable material that can readily be handled and prepared dimensionally for combined use with a rubber or synthetic rubber sealing strip to orient such a strip in a groove or slot in a work piece and to provide the anchoring instrumentality to lock the strip in a given relation within such groove or slot.
While a number of forms of the invention have been disclosed, embodying various puffable materials and in different combinations of use between the strips and the associated expansible materials, one other arrangement is illustrated in FIGS. 25 and 28 which has to do with a locked in or confined strip of puffable material carried in the seal strip.
The sealing strips shown in FIGS. 26 and 29 provide articles of manufacture that may be extruded and supplied with putfable compositions. Such strips, much like the other strips shown in FIGS. 19, 20, 21, 23 and 24, readily serve as ready made seal strips of various lengths which can be adapted to grooved units and secured therein according to their physical capabilities and through the methods of the present invention.
The arrangement shown in FIG. 26 is a composite seal strip 95 having a cavity 96 filled with a puffable material 97 which may be in solid stick form, or powdered or granular. The strip provides coplanar top faces 98 and 99 flanking the recess or concave slot that runs the length of the strip.
The core box part or section 101 in FIG. 25 is provided with a milled slot 102 having semi-circular undercut base cavities 103 and 104. The slot 102 provides parallel spaced orientation walls 105 and 106 which are adapted to snugly receive the strip 95 in an initially seated position as shown in FIG. 27.
The pulfable material 97 is preferably a compressed foamed epoxy resin subject to activation by the application of heat. Thus, with a suitable slot cover 107 which may be a matching core part, heat is applied by a torch or other means to heat the strip material causing the expansion of the material 97 into a developed shape or form 97a as in FIG. 28. The action is to raise the strip to engage the secured slot cover 167 while simultaneously expanding the epoxy carrier portion of the strip laterally into the aligned base cavities 103 and 104 as expanded or ballooned portions containing the puffed epoxy material.
After cooling, the epoxy portions 108 and 109 and strip parts 110 and 111 provide locking ledges or ridges that hold or anchor the strip 95 in oriented position within slot 102. A matching slot is then milled into the mating section to receive a companion seal strip 112 of the character illustrated in FIG. 29. Strip 112 has the raised gothic arch shaped ridge 113 and a cavity 114 follows the ridge and top part of strip 112. A compressed epoxy resin insent 115 is carried in a cavity 116 in the lower part of the strip 112. In general, both cooperative strip forms are provided with cavities that confine the epoxy resin more or less in line with the undercut slot portions. This provides strip expansion in controlled areas or planes to produce the locking instru' mentalities and the upward actuation of the strip toward the mouth level of the slot containing the strip.
FIG. 30 shows a strip 117 having a cavity 118 having a compressed wooden stick 119. The thinner wall portions of the strip contain perforation 120 and 121 to permit liquid access to the wooden stick for expansion purposes in the manner hereinbefore described.
FIG. 31 is added to demonstrate one way in which one core box section may be held at a low temperature to prevent reactivation of a processed strip while installing the companion strip. The core box unit is placed in a pan 122 having a cooling solution 123 to counteract excessive heat transfer from section 1 to section 2. A torch 124 is here shown as supplying heat to section 2 for activating the pufiable material in an installed strip in that section.
The foregoing description of the method and means herein disclosed has been more or less specific to the apparatus shown in the drawings. Certain modifications are considered possible and are contemplated in the practice of the invention disclosed. The extent of such modifications shall, however, be governed by the breadth and scope of the language of the hereinafter appended claimed subject matter directed to the method and means for providing sealing structures for cavitated assemblies.
What I claim is 1. The method of providing a seal strip in a surface of one of two separable coacting meeting surface areas of a pair of parts as a sealing means between the meeting surfaces of said parts to counteract fluid flow between such parts under differential pressure conditions existing on opposite sides of said parts comprising forming a recess in the meeting surface of said one part, applying a quantity of activated puffable material in the recess, placing an independent seal element in said recess in contact with said material to one side of the meeting surfaces of said parts, uniting the two coacting parts along their meeting surfaces to confine said pufiable material and said seal element between the meeting surfaces of said parts and the inner confines of the recess in said one part, and maintaining said parts in such united surface to surface position until the permissible expansion of said material ceases.
2. The method of claim 1 using a putfable material comprising a substance selected from a group characterized by polyisocyanate and polyurethane as the expansible medium to fill the available slot space and to set and cure within the confines of that space.
3. The method of claim 1 wherein the seal element comprises a resilient substance constructed from materials selected from a group characterized by rubber and rubber-like compositions.
* 4; The method of claim 1 wherein the seal element is constructed from a non-compressible synthetic rubber comprising high acrylonitrile Buna N rubber.
5. The method of introducing a seal structure into a surface of one of two coacting parting surfaces of a pair of engaging separable parts to establish sealing means therebetween to counteract fluid passage between opposite sides of said engaging parts which comprises removing a portion of the material below the surface of one of said parts, applying a quantity of a chemical composition into the formed cavity to be rendered expansible through activation by an added catalyst, placing a non-compressible seal strip into the cavity in contact with the chemical composition, and closing off said formed cavity by disposing said two parts into their coacting engaging position, said chemical composition functioning to force said seal strip into sealing contact under pressure with the other of said parts and providing means to anchor said seal strip within said cavity.
6. The method of claim 5 wherein said chemical composition comprises a chemical selected from a group of materials characterized by polyisocyanate and urethane. 7. The method of anchoring a seal strip into a surface of one of two coacting touching elements to seal the area between opposed contacted surfaces thereof to counteract fluid flow between said elements through said area of the contacted surfaces which comprises forming a recess in said one element, applying a quantity of a viscous chemical composition into said recess including a catalyst to render said composition expansible, inserting a seal strip into said cavity to a level below the surface lying adjacent said recess, providing said strip with irregular dependent elementsto penetrate said viscous composition during insertion to cause said composition to flow about said dependent elements, closing said recess through operative contacting engagement between said coacting elements, and permitting said composition to swell within the area of the recess below the seal strip to force the latter into sealing contact with said second coacting element while simultaneously causing forceful gripping and retainment of said strip through pressurized contact of said composition about and between said irregular depending strip elements and through the forceful engagement of the composition in the direction of the marginal confines of said recess.
8. In cavitated assemblies subjected to internal pressurized conditions, the method of providing sealing means along marginal parting line surfaces of adjacent separable coacting par-ts of such assemblies to prevent leakage which comprises providing opposing recesses in the surfaces of said parts, applying activated puffable compositions to said recesses, inserting flexible rubber-like seal material into said recesses upon the pulfable compositions therein, controlling the amount of swelling of each portion of said puffable composition respectively for moving the associated rubber-like seal materials into predetermined final positions with respect to their adjacent recesses to form coacting but separable sealing means.
' 9. The method of claim 8 wherein said .pufiable compositions comprise substances selected from a group characterized by polyisocyanate and urethane. p
10. The method of establishing a seal between mating and abutting surfaces that form. a parting joint between 'two coacting members of a cavitated assembly comprising providing a groove in the surface of at least one member, applying an activated puffable composition in said groove, introducing a sealing element into said groove, and en closing the open end of said groove to limit the extent of the displacement of said sealing element in relation to said 'groove and to positively govern the permissible amount of expansion of the puifable composition within said groove.
1l.' A sealing structure operative between two coinc'ident and physically abutting surfaces of a pair of coacting members comprising a first seal strip for one of said members having a rounded recess along the length thereof extending inwardly away from the abutting surface of said one member, and a second seal strip for the other of said members having a projection thereon extending therealong and disposed outwardly with respect to the abutting surface of said other member for disposition within said recess of said first seal strip, said recess of the firstseal strip being lesser in depth than the height of the projection on said second seal strip, and wherein the mouth of the recess is wider than the width of the projection.
12. A sealing structure connected with a surface area of an element comprising a slot formed into the surface of said element, a sealing strip in said slot, and retaining means for said slot to hold said strip in a predetermined relation with respect to said slot comprising a incompressible material compacted within said slot, said strip being provided with anchoring means, and said compacted material encompassing said anchoring means of said strip.
13. A sealing structure as in claim 12 wherein said incompressible material comprises a cured composition selected from a group of substances characterized as polyisocyanate and urethane.
14. The method of providing a seal strip along at least one surface of one of two coacting parts as a sealing means therebetween comprising forming a slot in the surface of said one part, providing a seal strip for the slot having a sealing head and displaceable leg units having portions thereof meeting to form a chamber adjacent the head, placing a putfable material within said seal strip chamber, inserting said seal strip wholly into the slot with said head toward the open slot, and then covering said slot to control the amount of expansion of said puffable material and the amount of movement of said respective seal strip parts within said slot to orient said strip and to secure said strip within said slot by means of said displaceable leg portions.
15. The method of claim 14 wherein said pufiable material comprises a substance selected from a group of materials characterized by polyisocyanate and polyurethane subject to activation by a catalyst.
16. The method of claim 14 wherein said puifable material comprises a soft compressed wood selected from a group of materials characterized by sugar pine, white pine, basswood, cork pine and balsa, subject to activation by water.
17. The method of claim 14- wherein said pulfable material comprises a compressed foamed epoxy resin subject to activation by the application of heat.
18. A sealing structure for at least one surface area of the parting line surfaces of companion coacting cavitated members comprising a groove having undercut edges, and a seal strip for said groove having a sealing head and depending legs, said legs being arranged for direct contact with the groove walls and including feet for insertion into said undercut edges of the slot,' said legs being initially disposed in abutting contact beneath said head to form a chamber with said head and having a puifable substance carried in said strip chamber to provide means to secure said strip into said slot under the expansion of said puffable substance.
19. A sealing structure as in claim 18 wherein said pufiable substance comprises compressed soft wood, and access port means are provided into said slot and into said strip chamber to permit the introduction of water to said compressed soft wood. a 20. A sealing structure as in claim 18 wherein said puffable substance is compressed foamed epoxy resin material subject to expansion upon the application of heat.
21. A sealing structure as in claim 18 wherein said seal strip chamber is generally of trapezium shape in cross sectional area, and wherein said puffable substance comt prises a flexible compressed wooden liner of generally trapezium shape in cross sectional area.
22. An article of manufacture comprising a sealing means adapted for confinement in a slot in the surface area of a member of a cavitated assembly comprising a deformable strip providing a sealing body having coacting leg portions depending angularly therefrom to meet in abutting contact with each other beneath the sealing body to establish a cavity beneath said body, together with a material having expansible properties disposed within said leg formed cavity of said deformable strip, said expansible material being selected from a group of substances characterized by polyisocyanate and polyurethane.
23. An article of manufacture comprising a resilient strip having a head providing an exposed sealing surface thereon and thin walled portions formed coextensive with said head to establish an aperture beneath and across the head in a position oppositely related to the exposed sealing surface thereof, said head having an expansible material confined within said aperture, said expansible material comprising a compressed foamed epoxy resin subject to expansion under the application of heat.
24. An article of manufacture comprising a resilient strip having a head providing an exposed sealing surface thereon and thin walled portions for-med coextensive with said head to establish an aperture beneath and across the head in a position oppositely related to the exposed sealing surface thereof, said head having an expansible material confined within said aperture, said expansible material comprising a compressed wood member subject to expansion under the addition of moisture, and wherein said thin walled portions of said strip include perforations for moisture access to the strip aperture and to the confined wood member therein.
25. A seal structure for a surface area comprising, in combination, a walled slot in said surface, said slot having recessed areas along the side walls thereof, and a resilient seal strip confined within said slot comprising a sealing section and an expansible section, said expansible section providing deformable walls surrounding an aperture containing an expansible material, said strip and slot being proportioned to generally align said expansible section of the strip with the recessed areas of said slot.
26. A seal structure as in claim wherein said expansible material is a heat sensitive substance comprising a compressed foamed epoxy resin.
27. A seal structure as in claim 25 wherein said slot recesses are located at the slot bottom, and said expansible section is at the strip bottom to dispose said expansible material generally in line with the recesses in said slot walls and adjacent the bottom of the slot.
28. A seal structure as in claim 25 wherein said slot depth is greater than the vertical height of said strip prior to the expansion of said expansible material.
29. The method of providing a surface area of an article with a sealing element bearing a given fixed relation with respect to a surface area of said article, which comprises removing a portion of said article to create a recess in said surface area having walls intercepting said surface area, introducing an activated puifable composition into the lower portion of said recess, superimposing a sealing element within said recess and over said puffable composition in fitted contacting engagement with the walls of the recess, permitting limited expansion of said puifable composition and arresting the expansion with said sealing element when said element assumes a predetermined relation in said recess with respect to said surface area of said article, and thereafter permitting said puifable substance to become deactivated to orient said sealing element in said recess in a given relation with respect to the surface area of the article.
30. The method of claim 29 wherein the removing of the portion of the article to create the recess for the sealing element includes the formation of spaced parallel walls to define said recess, with said sealing element including complementary spaced surfaces thereon to coact with the recess walls to trap the puffable composition wholly within the confines of the recess for expansive reaction in the direction of said sealing element only.
31. The method of claim 29 wherein said putfable composition comprises a substance selected from a group of materials characterized by polyisocyanate and polyurethane which are subject to activation by a catalyst.
32. The method of providing a surface area of an article with a prelocated seal element occupying a given fixed position with respect to a surface portion of said article, which comprises removing a selected portion of the article to form a recess lying below the surface portion of the article, introducing an expansible medium into the remote depth of the recess, inserting a seal element into the recess and over the expansible medium, causing expansion of said medium within said recess to react against said seal element to move the latter in the direction of the recess mouth, and selectively arresting the motion of said seal element to contain further expansion of said medium to orient said seal element in a predetermined position in said recess and with respect to the surface portion of the article carrying the seal element.
33. The method of claim 32 wherein said seal element is incompressible.
'34. The method of claim 32 wherein said expansible medium comprises a substance selected from a group of materials characterized by polyisocyanate and polyurethane which are subject to activation by a catalyst.
35. The method of claim 32 wherein said expansible medium comprises a foamed epoxy resin subject to activation by the application of heat.
36. The method of claim 32 wherein said expansible medium comprises soft wood selected from a group of materials characterized by sugar pine, white pine, basswood, cork pine and balsa, subject to activation by fluid.
37. An article of manufacture comprising core box sealing means for a parting line surface of separable mating core box sections and carried in a slot provided in the parting line surface in one of said sections, said sealing means comprising an elongated preformed resilient seal strip having an elongated sealing head thereon to fit the slot in said one section, displaceable head anchoring elements connected with and depending from said head at spaced locations thereon extending along the length of the head and confined within the slot of said one section, and a mass of heat responsive pufr'able material carried by said seal strip, said pulfable material being retained by said strip in the longitudinal area defined by the head and the spaced anchoring elements on the head, said head being secured into the slot of said one section by the forced displacement of said anchoring elements under activation of said puifable material with the application of heat.
38. An article of manufacture comprising a seal means for a slot in the parting line surface area of a mating core box part and comprising a deformable strip providing an elongated sealing body to fit the slot in said part and constructed with coacting leg portions extending iangularly away from said body and therealong within the slot, said angular leg portions meeting in abutting contact with each other outwardly and away from said body to form an elongated cavity between said body and the leg portions, and a physically enlargeable means in the form of a heat responsive expandible substance assembled with said deformable strip, said body and the angularly extending leg portions comprising retaining means to orient said expandible substance within the elongated cavity established by said body and the angular leg portions thereof, said sealing body being tightly secured in the slot of said part with the extending leg portions under activation of the expandible substance by application of heat.
39. An article of manufacture comprising a seal means for a slot in the parting line surface area of a core box part, and comprising an elongated seal strip constructed with a sealing head portion to fit into the slot of said part and having an apertured section extending through the cross sectional area of said head portion, said apertured section of said head portion being fully enclosed and including thin wall external portions capable of expansion beyond the adjacent exterior limits of the head portion, and a selectively pufiable means disposed within said apertured section of said head portion to affect the expansion of said thin wall external portions within the slot of said part, expansion of said pufiable means providing the means to secure said sealing head Within the slot in the core box part.
40. An article of manufacture comprising a sealing unit for one of a pair of mating engaging surface members and for securernent into a slot provided in the surlt'ace of said one member to engage the other of said members, said sealing unit comprising a resilient seal strip having a head to fit the slot of said one member and provided with an exposed sealing area thereon and including continuous thin walled portions formed coextensive with said head to establish an enclosed cavity beneath and across the underside of the head in a position 18 oppositely related with respect to the exposed sealing area of said head and within said slot, said continuous thin walled portions being expandible relatively to the head toward the walls of said slot in said member, and an expansible material disposed within the confines of said enclosed cavity beneath said head to affect expansion of said thin walled portions to secure said head into the slot of said one member.
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