US 2533742 A
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Dec. 12, 1950 E. J. POLTORAK RING PACKING AND METHOD OF MAKING THE SAME Filed March 11, 1947 Patented Dec. 12, 1950 UNlTED STATES PATENT. OFFICE RING PACKING AND METHOD OF MAKING THE SAME Emil J. Poltorak, Somerville, N. J., assignor to Johns-Manville Corporation, New York, N. Y., a corporation of New York Application March 11, 1947,- Serial No. 733,875
6 Claims. (Cl. 28818) for sealing engagement with the moving part.
They are made of a fabric base, such as a cotton or asbestos cloth impregnated with a heat-curable, yieldable material, usually a rubber compound.
In the manufacture of the conventional packings, a strip of the cloth carrying the rubber compound as an impregnant, or partial impregnant, is formed into a multi-ply ring by wrapping a plurality, say, 2 or 3 convolutions of the strip on a mandrel, or the like. Alternatively the multi-ply construction may be obtained by forming but a single convolution and then folding the ring approximately on the center line to form a double ply, or by inwardly folding the margins toward the center to similarly form a double ply.
Also, it has been proposed to make the multiply thickness rings by laminating a plurality of thicknesses of the rubberized fabric and die-cutting the rings. The rings made in any of the ways described above are preferably pre-folded to an approximately V cross-section and are then placed in molds of the finished shape of the rings particularly where they have irregularities of surface or dimensional variations. Due to the manner in whiel'iv the fabric rings have been made in the prior practice described above, the relatively unstretchable, multi-layer fabric extends as a continuous ring into, and forms the basic element of, the lips whereby they are relatively stiff and unyieldable. The instant invention overcomes this disadvantage and imparts stretcha 2 like material whereby distortion of the lips, which may be necessary to conform the packing to irregularities of surface or dimensional changes of the part against which it seals, requires only that the rubber between the pleats be stretched or distorted.
A further object of the invention is the provision of a method of making a packing as described above.
The invention will be more fully understood and further objects and advantages will become apparent when reference is made to the following more detailed description of a preferred embodiment of the invention and to the accompanying drawings in which: 1
Fig. 1 is a perspective view of a ring packing in accordance with the invention with a portion broken away for clearance of illustration;
Fig. 2 is a sectional view on an enlarged scale, taken on the line 2-4 of Fig. 1 and illustrating one typical ring cross-section;
Fig. 3 is a view similar to Fig. 2 illustrating a second typical ring cross-section;
Fi 4 is a plan view of a fabric strip as em' ployed in the instant invention;
Fig. 5 is a perspective view illustrating a step in the manufacture of the packing;
Fig. 6 is a perspective view illustrating a further step in the manufacture of the packing;
Fig. 7 is a sectional, detail view of the packing at a further stage in its manufacture; and,
Fig. 8 is a fragmentary, sectional view illustrating the final molding operation.
Referring now to the drawings, the invention is illustrated as embodied in a typical ring packing ill of any conventional cross-section, such as the V-shape shown in Figs. 1, 2 and 8, or the U-shape shown in Fig. 3, the packing having projecting lips I! and I, either or both of which are adapted to seal against a moving part. It will be understood that the particular packing shape is immaterial, the concept of the instant invention being embodied in ring packings of any of the known styles but having sealing lips with a flexibility and yieldability not heretofore known.
Referring now particularly to Figs. 4-8, inclusive, the structure of the packing will be described in conjunction with the description of its method of manufacture. In Fig. 4 there is shown a strip of fabric 20 which is suitably a woven fabric of cotton, asbestos or other conventional material, the fabric being impregnated with a resilient, yieldable, stretchable compound which is curable by heat. In lieu of complete impregnation, the fabric may carry the compound as a coating which only partially impregnates the fabric. The compound conventionally used is a rubber compound, although resins or other compounds may be employed in conformity with the known prac-, tice of the art. The proportion of the compound employed may, of course, vary, depending upon the particular properties desired. but for purposes of illustration, where asbestos fabric is used, 40-50% of rubber by weight of the fabric may be employed. On the other hand, where a cotton fabric is used, the proportion is usually higher,
' to the desired thickness. The ends of the pleated strip are joined, suitably by cementing them together as indicated at 24 in Fig. 6, whereby the strip defines a ring having a continuous succession of transverse folds or pleats. At this point a single thickness of an unpleated cloth may be applied to the ring to provide a covering if desired without materially affecting the desirable characteristics of the finished packing. The ring is then preferably folded circumferentially at substantially its mid-point (see Fig. 7) to an approximately V cross-section, and the preformed ring is then inserted in a mold having male and female members 26 and 28, respectively, as illustrated in Fig. 8, of a configuration to mold the ring to the desired finished shape. As will be appreciated, in inserting the preform in the mold, it is necessary to distort it sufficiently to rotate the V from a substantially horizontal to a vertical position. This same condition is present in the manufacture of the conventional rings but in the instant case the distortion of the ring is greatly facilitated by its pleated character, inasmuch as the inner surface of the ring may contract and the outer surface expand sufficiently to readily, permit the inclusion of the ring within the mold. The ring is subjected in the mold to heat and pressure in a conventional manner to cause the rubber-like material to first flow sothat the fabric is substantially embedded in the rubber-like material, and to then become vulcanized or cured. When the packing is removed from the mold a construction, as shown in Fig. ,1, is obtained.
In the use of the ring, the lip l2 or I4, as the case may be, in contact with the relatively moving part, may readily yield, i. e., contract or expand, to accommodate itself to changes in contour of the relatively moving part with which it is in contact. In practice a decided increase in the flexibility of the lips has been found, greatly increasing the efficiency of the sealing action.
Having thus described my invention in rather full detail, it will be understood that these details need not be strictly adhered to but that various changes and modifications may suggest themselves to one skilled in the art, all falling within the scope of the invention as defined by the sub- Joined claims.
What I claim is:
1. A ring packing including a projecting lip built up to a multi-layer thickness by a succession of overlapping pleats with the fold lines thereof extending transversely of the ring and into said lip, the overlapping portions of the pleats being adhered together by the impregnant.
' 2. A molded ring packing including a projecting lip comprising a fabric base impregnated by and embedded in a rubber material, said base comprising a fabric strip built up to a plurality of thicknesses by a succession of overlapping, pleats with the fold lines thereof extending transversely of the ring and into said lip, the overlapping portions of the pleats being adhered together by the rubber material.
3. A molded ring packing'including projecting lips and a connecting portion comprising a fabric base molded to define said lips and connecting portion, said base being impregnated by and embedded in a rubber material, said base comprising a fabric strip built up to a plurality of thicknesses by a succession of overlapping, pleats with the fold lines thereof extending transversely of the ring and into said lips, the overlapping portions of the pleats being adhered together by th rubber material.
4. The process of making a ring packing comprising folding a strip of cloth carrying a heat curing, yieldable material to form a succession of overlapping, transverse pleatsconnecting the ends of the strip to form a ring, distorting the material of the ring to cause the fold lines of the pleats to lie in planes extending substantially radially of the ring, and molding the ring under heat and pressure to define a projecting lip, and simulta-- neously curing the yieldable material.
5. The process of making a ring packing comprising folding a strip of cloth carrying a rubber material to form a succession of transverse, overlapping pleats, connecting the ends of the strip to form a ring, distorting the material of the ring to cause the fold lines of the pleats to lie in planes extending substantially radially of the ring and molding the ring under heat and pressure to de-' fine projecting lips and a connecting portion and to vulcanize the rubber material.
6. The process of making a ring packing comprisingfolding a strip of rubberized cloth to form a succession of transverse, overlapping pleats, connecting the ends of the strip to form a ring, folding the ring centrally to have an approximately horizontal V cross-section, distorting the ring to rotate the V to an approximately vertical position, and molding the ring under heat and pressure to form the ring to the desired finished shape and to vulcanize the rubber.
' EMIL J. POLTORAK.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 414,882 Guibal Nov. 12, 1889 1,128,247 Headson Feb. 9, 19 5 1,162,384 Nichols Nov. 30, 1915 1,771,890 Hubbard et a1. July 29, 1930 1,981,782 DAubigne Nov. 20, 1934 2,251,211 Armstrong July 29, 1941 FOREIGN PATENTS Number Country Date Great Britain Dec. 16, 1903 Certificate of Correction Patent No. 2,533,742 December 12, 1950 EMIL J. POLTORAK It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: 1
Column 2, line 18, for the word clearance read cleamess; column 3, line 9, for 40-50% read 40-45%; column 4, lines 10 and 21, respectively, after overlapping strike out the comma;
and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oflice.
Signed and sealed this 20th day of February, A. D. 1951.
THOMAS F. MURPHY,
Assistant Oommissioner of Patents.