US 3664799 A
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United States Patent 3,664,799 POWDER COMPACTING PRESS Claude Rollin Wallick, Jr., William Edward Blodgett, and Donald Keith Lazor, Louisville, Ky., assignors to American Standard Inc., New York, N.Y.
Filed Nov. 4, 1969, Ser. No. 873,890 Int. Cl. 1328b 3/02 US. Cl. 425389 2 Claims ABSTRACT OF THE DISCLOSURE An isostatic powder press for compressing ceramic powders together to form a toilet bowl section, said press including one or more deformable membranes subjectable to fluid pressure to uniformly compress the powders to a substantially constant density throughout.
DRAWINGS FIG. 1 is an exploded sectional view of a toilet bowl having one of its major parts formed by a press of this invention.
FIG. 2 is a sectional view of a mechanism for loading powder into the invention press.
FIG. 3 is a cross sectional view of a press of the present invention adapted to form one of the toilet bowl sections shown in FIG. 1.
FIG. 4 is a sectional view of a press constituting another embodiment of the invention.
Drawings in greater detail--FIG. 1
FIG. 1 is an exploded view showing a toilet bowl 8 formed of six separate but connectable sections numbered 10 through 15. Each section may be formed from ceramic powders or pellets, as for example mixtures of ball clay, china clay and alumina. The powders for each section are loaded into a press and compacted to form a green uncured port of the desired shape. Thereafter the joinable edges of the various parts are moistened, and the parts assembled together in a conventional stick-up operation. The assembly is then dried, glazed and fired, as under conventional practice.
As shown in FIG. 1, the element identified by numeral 13 appears to be formed as part of bowl section 10. Actually element 13 (known as panplate) is formed separately from bowl section 10, and is later stuck onto section 10 by causing its lateral edges to seat against shoulder 22 pre-formed in the bowl section. The panplate is suitably curved, and the shoulders 22 are so configured that the joining edge or crack 23 is obliterated or eliminated in the finished article.
Bowl section 10 is the major section or part of the toilet bowl and is the most difficult to form under conventional practice. Under the present invention the green and uncured bowl section 10 can be press-formed from powders by means of the press shown in FIG. 3 or 4. Powder may be initially loaded into the press by the mechanism shown in FIG. 2.
As shown in FIG. 3, the press comprises two separate die mechanisms 25 and 27. Mechanism 25 forms the upper interior surfaces of the bowl section, and mechanism 27 forms the lower undersurfaces of the bowl section. Each die mechanism includes a supporting steel plate or shell, a rigid core, and a deformable elastomeric membrane. Relative vertical movement of the two die mechanisms allows them to separate at parting line 26 for removal of the formed article and insertion of the next powder charge. Such vertical movement can be accomplished by manual or mechanical means (not shown).
Patented May 23, 1972 Actual formation of the part is accomplished by introduction of pressure fluid into channels located behind the respective elastomeric membranes; the membranes act as transmitters of the fluid pressure to the powder charge.
Die mechanism 25 comprises a flat steel plate 32 having a rigid core member 34 secured to its upper face. Overlying core 34 is a deformable elastomeric bag or membrane 36 having its peripheral edge area 38 lying flat against steel plate 32. An annular steel plate 40 is suitably bolted to plate 30 to clamp the peripheral edge of the membrane 36 in place.
At selected points on its upper surface the core 34 is provided with channels or grooves 42, said grooves communicating with one or more passages 44 leading through the steel plate 32. Introduction of pressure fluid to passage 44 from a pressure source (not shown) causes the membrane 36 to be deformed away from the back-up surface of core 34, thus compressing the powders previously admitted to the powder space 46.
Die mechanism 27 comprises a steel shell 48 which encircles and fixedly contains a rigid die cavity member 50. This die mechanism further comprises a plunger assembly 52 which includes a steel plate 54 and a rigid core member 56 adhered to plate 54 by any suitable means (not shown). Overlying the exposed surface of core 56 is a second deformable elastomeric membrane 58 having its peripheral edge 60 clamped in place by means of an annular plate 66. Plate 66 is provided with an endless peripheral skirt or rib 72, as well as internal ribs 68 and 70, said ribs serving to anchor and confine the adjacent sections of the elastomeric membrane 58 so that said sections are incapable of movement relative to the plunger assembly 52. The plunger assembly (members 54, 56, 58 and 66) is capable of vertical slidable movement through an opening 73 formed in member 50. Normally the plunger assembly is maintained in the illustrated elevated position by compression springs 75; however when it is necessary to eject a formed part the plunger assembly is moved down by application of a downward force on plunger surface 77. Annular retaining ring 49, which is bolted to steel shell 48, restrains plunger assembly 52 in the elevated position.
As shown in FIG. 3, the lower face of core 56 is provided with one or more channels 74 which connect with passages 76 leading through plate 54. With the parts in their FIG. 3 positions pressure fluids can be simultaneously introduced into passages 76 and 44, thus causing the channels 74 and 42 to fill with fluid and produce movements of the membranes 58 and 36 away from the respective core 56 and 34 surfaces. The simultaneous movements of the two membranes 58 and 36 causes the mass of powder in cavity 46 to be compressed to the general configuration and thickness denoted by dotted line 78. In general, the movement of each membrane 36 or 58 is in a direction normal to the backup surface of the respective core. The membranes thus have difierent portions thereof moving in different directions as determined by the contour of the core sections, so that the membranes function somewhat in the manner of complex motion dies, but without the mechanical complications or difficulties. The use of multiple membranes as shown in FIG. 3 is therefore advantageous for pressing powders into complex shapes which may have hidden crevices or undercuts therein. Since the membranes move at right angles to the adjacent core surfaces they have direct compressive action on the powder granules without any substantial traverse sliding contact between the adjacent powder particles or between the powder particles and the membrane surfaces. The general configuration of the article is therefore well preserved, and there is little tendency for the wall sections to be excessively 3 thinned out in any particular area. Compaction using multiple deformable membranes provides minimum average particle movement for a given degree of compaction and therefore provides uniform density in the final product, thus contributing to maximum strength without requirement for excessive wall thickness.
Ejection of the compacted article from the die cavity is accomplished after the die mechanisms 25 and 27 have been separated from one another at parting line 26. Mechanism 27 can be drawn up from mechanism 25 and/or mechanism 25 can be drawn down from mechanism 27 by suitable means, not shown. With the two die mechanisms thus separated from one another a downward force can be applied to plunger surface 77 to move the plunger downward through opening 73, thereby ejecting the compacted article 78 from the press cavity.
It will be noted from FIG. 3 that the end edges 82 and 84 of the toilet bowl section are formed by machined surfaces on members 40, 68, 70 and 72. These edges 82 and 84 are the upper and lower edges of the FIG. 1 bowl section which are to be joined to the bowl sections 12 and 14, respectively; they should therefore be fairly flat, without ridges or depressions, if they are to correctly mate. By forming edges 82 and 84 on machined surfaces the edges are not likely to be wavy, hilly, etc. due to any variations in fluid supply pressure, elastomer durometer, elastomer thickness, etc.
It is of some importance that the planar outline of the compacted article be maintained Within fairly close dimensional tolerances, especially the peripheral outline of the article immediately adjacent the bowl section lower edge 84. Thus is because the surface area of sections 10 and 14 must be continued uninterrupted to eliminate objectionable cracks or joints in the finished article. The FIG. 3 compacting apparatus is designed so that wall surface areas at and adjacent to edge 84 are formed by rigid cavity surfaces which are dimensionally stable and which are the same irrespective of any minor variations in deformation of member 74 during the application of fluid pressure through passages 76 and 44.
FIG. 2powder loading FIG. 2 schematically illustrates one mechanism for loading powder onto membrane 36. The loading operation is performed with the upper die section removed from the lower die section 25, so that the upper face of membrane 36 is exposed to receive powder thereon. The powder is initially delivered from a hopper 90 which seats on a powder box 92. Box 92 has a lower surface 94 configured to the same shape as the face of membrane 58 when said membrane is in its normal unstressed state as shown in FIG. 3. Box 92 is preferably provided with one or more passages 96 which communicate between a manifold space 98 and respective porous metal filters 100 disposed at selected points on surface 94.
Application of a vacuum to manifold 98, coupled with the sudden application of a substantial volume of gas from gaseous pressure pump 99 to space 102, causes the powder in hopper 90 to be fluidized, and to discharge rapidly into the space 104 to produce a lightly compacted powder layer on the surface of membrane 36. After removal of box 92 from die mechanism 25 it is intended that the lightly compacted powder layer adhere to the elastomeric membrane 36 rather than to box surface 94. If necessary the powder layer can be prevented from adhereing to the box surface 94 by previous application of powdered mold release agents to surface 94; also a positive gas pressure can be produced in manifold 98,
to act through passages 96 to thus eject the powder preform away from surface 94.
FIG. 4 press FIG. 4 shows a press generally similar to the FIG. 3 press except that the upper deformable membrane 58 has been omitted. Instead the lower face of plunger 52 acts as a fixed die surface.
The principal feature of the present invention is the construction of the die mechanisms shown in FIGS. 3 and 4, whereby the single or multiple deformable members 36 and 58 are utilized to heavily compact the powder material in a manner to produce a green ware article having closely toleranced dimensions and uniform density.
1. An isostatic powder press for compressing a toilet bowl section which is to be later joined with other bowl sections at its upper and lower peripheral end edges: said press comprising first and second die mechanisms advanceable toward each other to define a powder cavity, and retractable from each other to permit discharge of the formed toilet bowl section; said first die mechanism comprising a rigid cavity member contoured to form the external undersurface 0f the bowl section, a first central rigid core section, and a first deformable membrane shaped to form the interior undersurfaces of the bowl section; said first membrane lying against said first rigid core section and having its peripheral edge sealed thereto; said first core section having fluid passages therein for admitting pressure fluid to the dead space between the membrane and the core section; said second die mechanism comprising a second convex core section locatable within the space circumscribed by the first die mechanism, and a second deformable membrane shaped to form the interior upper surfaces of the bowl section; said second membrane lying against the second core section and having its peripheral edge sealed thereto, and said second core section having fluid passages therein for admitting pressure fluid to the dead space between the second membrane and second core section, whereby when both dead spaces are pressurized the membranes are deformed toward one another to compress the powder.
2. The powder press of claim 1 wherein the first die mechanism comprises two relatively movable parts, one of said parts being the aforementioned rigid cavity member, and the other part being a plunger element slidably received in a central opening of the rigid cavity member for ejection of a pressed powder bowl section from the cavity; said plunger element including the aforementioned first rigid core section and the aforementioned first deformable membrane.
References Cited UNITED STATES PATENTS 3,041,685 7/1962 Taccone 164170 X 3,238,576 3/1966 Taccone 164-170 X 3,156,958 11/1964 Miller et a1 164170 3,172,153 3/1965 Lodmis et al. 1,177,240 3/1916 Gates.
.I. SPENCER OVERHOLSER, Primary Examiner B. D. TOBOR, Assistant Examiner U.S. Cl. X.R.