Seal packing fluid seals for extrusion machines

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Drawing sheet — no readable text.

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United States Patent Office 3,364,523 Patented Jan. 23, 1968

3,364,523 the seal rings which seal off opposite ends of the sealing SEAL PACKING FLUID SEALS FOR liquid chamber have enough axial contact pressure to EXTRUSION MACHINES Secure a substantially liquid-tight seal against both the Heinz Schippers, Reinscheid-Lennep, Germany, assignor to Barmer Maschinenfabrik drive shaft coupling the seal housing. Some adjustments, pertal-Oberbarmen, Germany Aktiengeselischaft, Wup necessary from time to time, of the axial pressure of the Filed May 18, 1966, Ser. No. 551,127 Outer ends of the adapter sleeves against both sealing Claims priority, application Germany, May 28, 1965, ring packs take place simultaneously in both axial direc

nut.

through simple rotation of the common adjusting

O Many of the media used as sealing liquid, upon their actual contact with the synthetic thermoplastics being

ABSTRACT OF THE DISCLCSURE extruded in the extrusion machine, are reactive with or Extrusion machines for extruding thermoplastics with ing detrimental to the synthetic thermoplastics. Hence, a seal vacuum drawn on feed section of screw housing and 15 liquid which is neutral with respect to the thermo including rotating screw in cylindrical passage of screw aplastics is preferred. It is, therefore, recommended that mineral oil be utilized as the sealing liquid. Regardless housing; transmission drive; socket type cylindrical of the good sealing effect provided by the invention, coupling connecting screw and drive; stationary seal traces of sealing liquid seep between the seal ring packing housing about coupling with annular sealing liquid cham and the driving shaft coupling rotating relative thereto. ber surrounding socket of coupling; coaxial, closely spaced 20 The passage even of small quantities of the sealing liquid cylindrical sleeves in chamber about socket with screw into the screw housing of the extrusion machine may be threads of opposite hand on contiguous ends of sleeves; prevented by means of a collector ring disposed in the nut with screw thread portions of opposite hand threaded Sealing ring pack which is closer to the screw housing. An on threads of sleeves; set of packing rings at opposite outlet bore is provided in the seal housing for the carrying ends of chamber, said sleeves pressing against respective off of the sealing liquid collected in the collector ring. sets of packing rings; collector ring in one set of packing A preferred embodiment of the invention is illustrated rings closest to screw housing; short screw segment on in the drawing, wherein:

head end of screw outside socket and inside sealing ring FIGURE 1 is a side elevation of a fragment of a rotary for urging forwardly any thermoplastic leaked past seal drive transmission housing, and diametric sections of a ing ring; and collector passage for collecting and removing 30 liquid seal member and the feed end of a screw extruder; leaked thermoplastic thrust forwardly by screw segment. and

FIGURE

adapter 2 is an exploded view of the adapter nut and sleeves.

This invention, in general, relates to fluid seals about Referring to the drawing, the screw extruder 10 com a rotary drive of a worm or screw of an extrusion machine. 35 prises a screw housing it having a cylindrical passage 12 The invention is particularly useful in such extrusion in which rotates the screw or worm 3. The head end 14 machines for extruding thermoplastics wherein a vacuum of the screw shaft extends into a socket 15 of the drive is drawn on the feed section of the screw housing. shaft 6 of the rotary drive transmission (not shown) in The packings heretofore commonly used with extrusion 40 transmission housing 7. The spline 19 of socket 15 locks machines, such as gasket rings and sealing ring packings, transmission drive shaft 16 to the head end 24 of screw are alone not sufficient to insure the production and main drive shaft i8 and thereby provides a rotary drive coupling tenance of a vacuum in the feed section of the extrusion between said drive shafts.

machine, i.e., on the feed end of the screw housing and/or Theroplastic is fed into the feed end of screw housing its feed tube. In many fields, where particularly high 45 is through feed tube 20. By a conventional vacuum device demands are made on seal tightness, seals with sealing (not shown), a vacuum, indicated on the drawing by liquid are utilized. The latter seals require a construction arrow 2A, is drawn on the feed section of the screw adapted to the requirements of the special purposes of housing 11.

use. The primary object of this invention is to furnish a The screw 13 has a rear, annular flange 22 which sealing liquid packing adapted to the present special re 50 rotates against an edge of ring bushing 23 in the rear quirements of an extrusion machine. portion 24 of passage 2. The edge of bushing 23 and In accordance with the invention, a sealing fluid pack flange 22 are urged into rotary seal contact by a pack ing is provided between filler section of the screw housing of conical disc springs 25, one side of which pack bears and transmission housing for rotatably driving the screw. against annular shoulder 26 of a bushing sleeve 27 and The sealing fluid packing is disposed in a seal housing the other end of which bears against an annular shoulder surrounding the coupling between the transmission drive 55 28 on the seal housing 29. The bushing sleeve 27 urges, shaft and the screw shaft. This sealing fluid packing com under the resilient pressure of springs 25, the edge of prises a seal housing providing an annular chamber about ring bushing 23 into sealing engagement with flange the coupling. The annular chamber houses two nearly 22 to seal against flow of thermoplastic therebetween. abutting, coaxial adapter sleeves or rings surrounding the Should, however, some thermoplastic leak through the drive coupling in a manner to permit axial movement 60 rotary seal, the shaft 8 of the screw 3 has a short while preventing rotation. The nearly abutting end of screw segment 30 with flights in close proximity to the one sleeve or ring has an outer screw thread of left hand inner side of ring bushing 23. The screw segment 30 urges and the nearly abutting end of the other sleeve or ring any leaked thermoplastic forwardly toward an outlet hole has an outer screw thread of opposite, (right) hand. The 65 3 in the bottom of bushing 23. The outlet hole 31 sleeves or rings are slidable axially in opposite directions communicates with a downwardly-extending passage 32 in by rotating an adjusting nut spanning contiguous ends of screw housing 11. The lower end of passage 32 com the sleeves or rings and having screw threads of opposite municates with a tapped hole 33, which is normally closed hand threaded on the sleeve threads. The outer ends of off by the threaded plug 34. Plug 34 is withdrawn from the sleeves respectively press against packing rings in the 70 time to time to discharge accumulated thermoplastic. seal housing. This particular construction of the sealing liquid packing with an extrusion machine assures that areThe screw housing 11 and the transmission housing 17 rigidly joined by an intermediate housing 35 by

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means of a plurality of bolts 36 coupling rear annular liquid and for the control of the level of the liquid. Tube flange 37 of screwing housing 11 to front flange 38 of 68 and chamber 48 are closed by means of the screw cap housing 35 and coupling rear annular flange 39 of housing 69.

35 to front wall 40 of the transmission housing 17. The It is thought that the invention and its numerous front flange 41 of seal housing 29 is coupled by a plurality attendant advantages will be fully understood from the of bolts 42 to the radically inner portion of front annular foregoing description, and it is obvious that numerous flange 38 with a ring gasket 43 inserted. Cylindrical end changes may be made in the form, construction and 44' of seal housing 29 matingly fits into the inner cylin arrangement of the several parts without departing from drical wall 45 of the flange 38. the spirit or scope of the invention, or sacrificing any of The rear end of seal housing 29 has a ring shaped O its attendant advantages, the form herein disclosed being a closure cap 44 bolted thereto. Its ring flange 45 extends preferred embodiment for the purpose of illustrating the into the rear opening of seal housing 29. The forward end invention.

of seal housing 29 has a ring lip 46 forming an annular The invention is hereby claimed as follows: shoulder against which bears the forward pack of pack 1. In a machine for extrusion of thermoplastics by a ing rings 47. The larger diameter rear portion of seal 5 rotating screw in a cylindrical passage of a screw housing, housing 29 has, when closure cap 44 is mounted therein, said machine having vacuum means for drawing a an annular chamber 48, the latter adapted to contain the vacuum on the feed section thereof into which thermo sealing liquid. A rear pack of sealing rings 49 are mounted plastic is fed, and a transmission drive, and rotatable, in the space between the transmission shaft 6 and the cylindrical coupling means operatively connecting said rear portion of closure cap 44 and bear against the 20 stationaryscrew and said drive, the improvement comprising a annular rear lip 50 of closure cap 44. The sealing rings seal housing about said coupling means, means 47 and 49 may be made of the usual materials, e.g., felt, in said housing defining an annular sealing liquid chamber asbestos, or spun or interwoven polytetrafluoroethylene. facing said coupling means, a pair of closely spaced, Two adapter sleeves or rings 51 and 52 are non 'coaxial, cylindrical sleeves surrounding said coupling rotatably and axially slidably mounted in seal housing 25 means in said chamber, means limiting movement of Said 29 and its closure cap 44. This mounting is provided by sleeves to movement in the axial directions relative to said bolts 53 and 54, which extend through the seal housing housing, screw threads of opposite hand on respective, and closure cap, respectively. The ends of the shanks of contiguous ends of said sleeves, a nut having screw said bolts having small pins fitted into narrow axial slots thread portions of opposite hand respectively threaded 56 in the respective adapter sleeves. The pins and slots 30 on said screw threads of said sleeves, a set of packing prevent rotation of said sleeves but permit axial move rings in respective opposite axial ends of said chamber, ments thereof. and respective opposite ends of said sleeves pressing The nearly abutting, contiguous ends of sleeves 51 and against respective sets of packing rings to compress said 52 have outer screw threads 57 and 58 of respective packing rings and form Substantially fluid tight contact opposite hands. An adjusting nut 59 is internally threaded 35 between said rings and said coupling means. from the center outwardly with mating screw threads 2. In a machine as claimed in claim , a collector ring 60 and 61 of respective opposite hands. The nut 59 con interposed in said packing rings closest to said screw tains a plurality of radial bores 62 adapted to receive a housing, and passage means in said seal housing for drain pin of a tool (not shown) used to rotate the nut. Thus, 40 ing3.sealing liquid collected in said collector ring. A machine as claimed in claim 1 wherein said rotation of adapter nut 59 spreads apart or draws together the sleeves 51 and 52, thereby increasing or decreasing the coupling means comprises a drive shaft with a cylindrical pressure of the opposite ends of the sleeves on the respec socket, said chamber surrounding said socket and said tive packs of sealing rings 47 and 49. packing rings being in substantially fluid tight contact The pressure exerted in this manner on the sealing with the cylindrical wall of said socket, a head end of packings may at any time be adjusted easily and rapidly 45 said rotating screw splined in Said socket, Seal ring means according to the particular requirements or adapted there sealing said head end of said screw at said feed section, to, respectively. An ordinary security member, not shown, a short screw segment on said head end outside said may be used to prevent further twisting or rotating of the socket and inside said ring means for urging toward said adjusting nut. It may consist of a releasable spring-tongue 50 feed section any thermoplastic material leaked past said fixed on the sealing housing 29, which engages in cor ring means, and means for collecting and removing the responding notches or grooves on the adjusting nut 59. leaked thermoplastic from said ring means. When desired, the sealing liquid in the chamber 48 may References Cited be drained through the tapped outlet opening 63 upon removal of the threaded plug 70. UNITED STATES PATENTS Between the sealing rings 47 of the front seal packing 55 1,337,227 4/1920 Hoffman ------------ 285-32 is disposed a collector ring 64 for the collecting of the 2,217,686 10/1940 Kreher ---------- 277-108 X sealing liquid which has leaked along the drive shaft 2,436,514 2/1948 Jennings ----------- 277-64 X coupling. Several radial bore-holes are distributed on the periphery of the collector ring 64 and permit the passage 60 2,929,646 8/1951

of the leaking fluid through the collector ring. The fluid flows by gravity through the outlet passage 65 and the 3,067,462. 12/1962 Kullgren.

evacuation opening 66. The evacuation opening 66 is 3,101,199 8/1963 Hartnagel -------- 227-69 X closed with a threaded plug 67, which may be provided 3, 110,060 1 1/1963 Rengert.

with a peephole or sighting tube, in order to be able to 65 3,164,388 11/1965 Ellis ---------------- 227-18 observe the quantity of the leaking fluid. In case the 3,204,294 9/1965 Brochetti --------- 18-12 X quantity of sealing liquid trickling through is found too FOREIGN PATENTS large, the sealing packings may thereupon be compressed further by turning the adjusting nut 59. 882,294 11/1961 Great Britain. The tube 68 is threaded into the seal housing 29 and 70 WILLIAM J. STEPHENSON, Primary Examiner. is provided for filling the liquid chamber with sealing

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UNITED STATES PATENT OFFICE

CERTIFICATE OF CORRECTION

Patent No. 3,364,523 January 25, 1968 Heinz Schippers

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 64, 'll/1965" should read - - 1/1965 - - ; line

Signed and sealed this 25th day of November 1969.

(SEAL)

Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents