US1583107A - Metallic rod packing - Google Patents

Description

Patented May 4, 1926.

UNITED STATES PATENT OFFICE.

JOHN BADEKER, OF CHICAGO, ILLINOIS, A SSIGNOR TO CHICAGO STANDARD METALLIC PACKING COMPANY, OF OMAHA, NEBRASKA, A CORPORATION OF NEBRASKA.

METALLIC ROD PACKING.

Application filed July 9,

used for maintaining fluid-tight joints about reciprocating rods, such as the piston-rods and valve-stems of stem engines. It is the object of my invention to provide ametallic packing especially suited for use on rods of which the portions which pass through the packing are not of uniform diameter. F or example, in locomotives the valve-stems have a variable travel according to the positionof the link-motion by which said stems are actuated and controlled, and in consequence of their variable travel the wear of the stems is not uniform, the stems wearing hollow, or becoming of smaller diameter at the center of the portions which pass through the packing. strokes there will be a leakage of steam through the packing at each'stroke, unless the packing is able to slightly contract as the worn or hollow portion of the stem passes through it, and to expand at the ends of the strokes to accommodate the larger portions of the stem. "Piston-rods, having a uniform travel, do not wear hollow, but become slightly'tapering, due to the pres sure of the steam upon the packing at the beginning of the strokes being greater than at the end when the steam has. expanded substantially to exhaust-pressure, the greater pressure upon the packing at the beginning of the strokes resulting in greater wear of the portions of the rod engaged by the packing at that time. lVith worn piston-rods, therefore, it is also necessary for the packr ing to expand slightly and again contract during successive strokes of the rod, in order to conform with the ditferentdiaineters of the opposite-ends of the rod.

My invention relates to metallic packing I high temperatures.

lVhen such worn stems make full.

1924. Serial No. 725,016.

A further object of' my invention is to provide a rod-packing in which the closingpressure exerted upon the packing is to re sisted as to reduce wear of the packing and rod to the minimumconsistent with maintenance of a fluid-tight joint between the parts. A further object of my invention is v "to prov de a cone-type rod-packing in which the segments are of a form which enables all of the surfaces to be machinefinished, whereby to enable the use of metals or alloys which cannot be successfully cast with surfaces sufficiently smooth and uniform' to be used without machining. Metals or alloys of this character must be used in packing which is exposed to high-pressure and super-heated steam, as the metals or alloys suited for die-casting are too soft to withstand the A further object of my invention is to provide means for maintaining a fluid-tight joint between the packing and gland in cases where the rod is at times tilted to positions at an angle to its normal axis.

In the accompanying drawings Fig. 1 is a longitudinal sectional view of a valvestem packing embodying my invention, Fig. 2 is a front view of the packing-ring, Fig. 3 is a detail section on the line 3--3 of Fig.

-2, Fig. 4 is a view showing the inner side.

of one of the outer segments of the packingring, Fig. 5 is a similar view of one of the inner segments, and Fig. 6 is a similar view of a slightly modified form of the inner segments.

In the drawings there is illustrated a valvestein 10 which extends through a stuffing-box-ll in the steam-chest 12, and adjoining the stuflfing box are stud-bolts 13 provided with nuts 14 by which a gland 15 is removably secured over the outeror open end of the box. At the inner, end'of the stufling-box a neck-ring 16 is disposed about the stem 10,1said ringpreferably having a bushing l'Tof bearing-metal. Said ring 16 carries the inner end of the follower-spring 18 and holds said spring in spaced relation to the stem, the other end of the spring being similarly supported by an annular flange 19 at the inner end of the follower 20. The main body of the follower is disposed within the gland-chamber, of which the diameter is greater than that of the smiling-box, and the follower is normally so positioned that there is a slight clearance between it and the shoulder formed at the inner end of the gland. At the outer end of the gland-chainbe r is disposed the guard-ring 21, of which the bore is larger than the stem 10, or ap proximately the same as the opening through the face of the gland, the outer end-face of said ring 21 being plane-surfaced and fitting slidably against the inner a aceol' ithe gland and forming a fluid-tight joint therewith. The inner end of the guard ring issphericah ly concave and-into said spherical concavity is fitted the spero-seginental face of the ball-ring-22, said spherical surfaces forming a fiuid-tight joint between the rings. The core or said ring 22 is substantially the same as the diameter of the stem, and the inner end-face of the ring is a plane-surface perpendicular to the axis of the stem; The packing-ring is disposed around the stem between the ball-ring 22 and the follower, and forms a fluid-tight joint with the stem and the engaged face of the ball-ring.

The packing-ring provided by my invention comprises the outer segments 2-l, the inner segments 25, and the filler-blocks 26, there being, in the structure shown, three each of said pa1'ts; and to: use on stems and rods which are worn hollow orta )erinp' this is the minimum number of segments whicl may be satisfactorily employed. In general form the packing-ring is a 'lrustuin of a right circular cone, having a cylindrical bore or opening concentric with the cone-axis, the r or base-end ol' the frustruin fitting Inst the plane end-lace of the ring 22, and the conical lateral surface fitting into the conical bore of the follower. The outer segments may be regarded as formed from an integral annular member by wide radial liQlfS, whereby to provide the clearancespaces between the parallel end-surfaces Zetl oi said segments. Adjoining the basc-ei'ids L- l; are short cylindrical lateral surfaces 243,

formed thc'groore 244 for reannular retaining-spring 27.

in. which is ceiving the The n rrow en s 1' l t I u- .4, are pcipencicu ai o the axis, and ad oin in" said ends are the C llIKlllCttlly bored suiiaces 1, 26 wh ch. ongage'the rod or stem. i-id accnt to the ends :2 '2 are shortcylindri bored surfaces 2%,

ion are (reticen to with tholateral sur- 1) 'PjK I, 0 1" 1, j A

o. i it s laces At! ineige as l 2 -swith the con c 2 18,01 which the clei 1 9 elemen f th,

"' tfQl-l Q T -sthe wide or base-ends the surfaces 252 lie in a common plane with the surfaces or. the outer segments. Lateral conical surliaces250 and lateral cylindrical surfaces 253 ht, respectively, against the surfaces 248 and 2-3 of the outer segments, and at the narrow ends are conical surfaces 255 which lit against the sin-laces 249 at the lips The tiller-blocks 26 are fixedly attached to the outer segments 21-, and normally till the spaces between the end-surfaces 251 of the inner segments. The outer segments have rec-tan iar grooves 29 at the centers of the surfaces 247 and 2&8, and the tillerbioclis have portions which fit into said grooves. in the segments 2% there are also formed openings which extend from the grooves 29 to the lateral conical surfaces 24-0, said openings being flared or countersunk-at their outer ends, and being filled by rivet-like pins 30 which extend from the outer edges oi the filler-blocks and are integral therewith. The ends 262 of the fillerblUChS are i a common plane with the ends 2&2 and 252 of the outer and inner segments, and the inner surfaces 236 are continuations ot the cylindrical surfaces 2% and 256 oi the segments. The narrow ends 265 of the tiller-blocks lit against the adjacent portions oi the surfaces 24-9 at the undercut lip 28. in the assembled parninga'ing the inner d outer segments are interspaccd circumrcntially, the ends of each lapping upon the adjacent ends or two segments of the other series. Before the mcltiiig is applied to the rod or stem on which it is used, the i'ln-Qill-li; are held together by the annular s p .ng 2?, and said spring is also useful in holding the segments together while the ring q placed upon or removed from the stem. heiore the conical end oi the ring has been inserted in the follower, or after the ring has been with-drawn therefrom. Said spring 2? also exerts a "ll part of the pr ssure which is Q'l'lGCillfO in rii upon the stem or rod to c. wear the frictionally contacti al force c :se, that result" 1,

follow 11in, the Y and cthe fl .t he filler-blocks.

steam from the gland, since the faces-242,

252 and 262 of the segments and filler-blocks are held in fluid-tight engagement with the inner face of the ring 22, the spherical face cf the latter forming a similar joint with the ring 21, and the latter similarly fitting against the inner face of the gland. About the stem itself a fluid-tight joint is completed by the segments 24: and 25, the inner segments 25 stopping off the clearance-spaces between the ends 241 of the outer segments. It is necessary, however, that the fluid-tight joints be maintained should the rod or stem be worn hollow or tapering, and that the packing-ring be able to contract progressively to compensate wear of the surfaces which contact with reciprocatingrodor stem. To enable closing or contraction of the ring, the filler-blocks are made of a relatively soft metal, such as to be e xtrusibly plastic under the pressure sustained thereby and at the temperature to which the packing is subject when in use. For moderate steam-pressures, lead is a satisfactory material for use in the filler-blocks, but for high-pressure and superheated steam it is necessary to employ a somewhat harder material, such as lead alloyed with a small proportion of copper, the percentage of copper being greater or less according to the pressure and temperature to which the packing is subject. The soft filler-blocks, being confined'at all sides and being pressed upon by the segments, gradually become thinner to enable the end-surfaces 251 to approach each other, and the excess material in the blocks is displaced toward the rod or stem, said excess material being worn and carried away by the rod as the displacement proceeds. The main or outer segments 2% may be of a metal such as copper'lead alloy containing a high proportion of copper, which is completely rigid or non-deformable under the pressures and at the temperatures to which the, packing is subjcct, and no change of shape of said segments necessarily occurs except that resulting from wear of the rod upon the cylindrically bored surfaces 246. The inner segments 25 should be of material sufficiently soft to be capable of being slightly bent at the central portions thereof, whereby their lateral conical surfaces 250 may remain in fluid-tight contact with the inner conical surfaces 248 of the outer segments when the latter have moved radially inward, but said inner segment-s should not have the extrusible plasticity of It will. thus be seen that thepacking-ring is enabled tocontract or close upon the stem or rod as the frictionally contacting surfaces are worn away, although the closing of the ring will be constantly resisted by the pressure necessary to upset or extrude the excess material from the filler-bocks, and wear of the packing thus reduced to a minimum.

Referring now to the operation of the packing-ring upon rods or stems which are not of uniform diameter, it will be seen that the contraction of the ring must occur to conform with the minimum diameter of any portion of the rod which passes through it, and that after such contraction has occurred the ring must expand as the larger portions of the rod are passing through it. hen the ring is expanded, the end-surfaces 251 of the inner segments will separate slightly from the adjacent sides of the filler-blocks at one or more of said surfaces, but the slight openings so formed will not permit leakage of steam, as the outer segments will still stop off all points at which steam from the gland-chamber might enter the opened joints, whereby to flow through the same to the bore of the ring 22 and thence escape.

As the taper or hollowness of the rods and stems on which the packing is used seldom exceeds thirty or forty thousandths of an inch, and as each segment of the packingring is in contact with less than one-third of the circumference of the rod-surface, the difference in the curvature of the rod-surfaces at the points of maximum diameter, and the corresponding arcs formed by vthe inner surface of any segment, (assuming that the latter has worn to conformity with the rod at a point of minimum diameter), are so slight that no appreciable leakage of steam will result by reason of such difference of curvature. In theory, of course, when the segments have Worn to conformity with the rod at its smallest diameter and then pass into contact with a portion of larger diameter, the rod will engage-only the endportions of the arcuate inner surface of any segment, while the intermediate portion of said arcuate surface will be held out of contact with the rod. In practice, however, the inner surfaces of the segments wear to a curvature having a radius intermediate that of the largest and smallest portions of the rod, and by reason thereof the difference of curvature of the rod-surfaces and segment surfaces becomes so small that no perceptible leakage occurs withinthe usual range of variation of diameter of the rods and stems.

The entire packing assembly is freely movable laterally within the gland, the guard-ring sliding against the inner face of the gland, to accomodate lateral movements of the stem from its normal position. In certain types of locomotives, the actuating means for the .valvestems in such "that said stems are attilnes, tilted to positions at an angle with their normal axes, and when such tilting occurs it is accommodated by rolling of the spherical face of the ring 22 within the recessed or concave face of the ring 21, the latter ring remaining perpendicular to the normal axis of the stem,'while the ring 22, the packing-ring, and the follower remain normal to the axis of the stem in its inclined position.

F or packing which is used for low pressures or at low temperatures, or both, it may sometimes occur that the resistance offered by the filler-blocks to the upsetting or deformation of their entire longitudinal area will not permit the closing of the ring necessary to compensate wear. Under such conditions, inner segments of the modified form shown in Fig. (i /nay be employed. In said modified form of the inner segments, the end-surfaces 251 which bear against the filler-blocks are reduced in area by shouldering or offsetting the same, the offset portions 251 being thus spaced from the filler-blocks, and the pressure available for upsetting the material thereby concentrated upon a smaller area, so that the pressure per unit of area is greater.

It will be noted that the segments of the packing-ring are of such geometrical form that the surfaces thereof may be readily finished or machined, principally by simple lathe operations, so that inexpensive manufacture thereof is possible. The undercut lips 28 on the main segments serve to limit the depth to which the inner segments may be pressed into the conical bore of the outer segments, and prevent the inner segments from falling inwardly when the packingring is chucked for boring the same to fit the rod on which it is to be used.

As the filler-blocks are fixedly secured to the outer segments and extend between the ends of the inner segments, said filler-blocks serve to retain the segments in their proper circumferential relations, besides resisting the closing of the ring and thereby reducing the frictional pressure upon and wear of the slidably contacting surfaces of the packing and rod.

Now, having described my invention, what I claim and desire to secure by Letters Patent is:

1. In a metallic rod-packing, a frustoconical packing-ring comprising an outer annular series of segments having concentric conical external and internal surfaces, said segments spaced to provide circumferential clearancespaces between the .ends thereof, an inner annular series of conical segments each extending across the clearance-space at adjacent ends of a pair of the outer segments and fitting against the internal conical surfaces of said outer segments, said inner series of segments being spaeed apart" at their" endsadjacent to the central vportions of the respective outer segments, and filler-blocks disposed between said spaced ends ofthe inner segments; said 'p'acki-ngring being bored to fit upon the rod, and each element of the ring extending to the cylindrical bore and to the base-end thereof; a. ring disposed about the rod and having a plane-surface engaged by the baseend of the packing-ring to form a fluid-tight joint therewith, and a conically bored follower pressed toward said ring and engaging the external conical surfaces of the outer segments to press the ring-elements toward the rod.

2. A structure as set forth in claim 1, in which the filler-blocks are afliXed to the outer segments of the packing-ring.

8. A structure as set forth in claim 1, in which the filler-blocks are of material extrusibly plastic under the pressures and temperatures to which the packing is sub ject when in use.

l. A structure as set forth in claim 1, in which, under the temperatures and pressures to which the packing is subject when in use, the inner segments are of material sufficiently soft to enable transverse bending thereof adjoining the clearance-spaces of the outer segments, and the tiller-blocks are of material extrusibly plastic.

5. A structure as set forth in claim 1, in which the filler-blocks are afiixed to the outer segments and are formed of material which is eXt-rusibly plastic under the temperatures and pressures to which the pack-- ing is subject when in use.

6. A structure as set forth in claim 1, in which the inner and outer segments each engage less than one-third of the circumferential surface of the rod.

7. A structure as set forth in claim 1, in which the internal conical surfaces of the outer segments are longitudinally grooved intermediate their ends, and the fillerblocks have portions entering and secured in said grooves.

8. A structure as set forth in claim 1, in wnich the outer segments have undercut lips adjoining the bore at the ends of the internal conical surfaces thereof, said lips extending within the adjacent portions of the inner segments to prevent inward displacement of the latter relative to the outer segments.

9. A structure as set forth in claim 1, in which the ends of the inner segments are partially cut away to reduce thearea of contact between the same and the filler-blocks.

10. In a metallic rodjoacking, a packingring of frusto-conical form having a cylindrical bore to receive the rod and comprising an outer annular series of segments spaced apart circumferentially and conically bored at the baseendthereof, an inaer" annular series of segments fitting about the rod and Within the comically bored ends of the outer segments, said 1nner segments having spaced apart ends circumterentially intermediate the ends of the outer segments and extrusiloly plastic members attached to the outer seginentsand extending between the ends of the inner segments, the inner and outer segments each contacting with the rod upon less than one-third of the circumference thereof; a conically bored follower the base-end of the packing-ring against which the latter is pressed by the follower and with Which it forms a fluid-tight joint.

JOHN BADEKER.

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