US 929027 A
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G. SGHUHMANN. SCREW COUPLING. AfPPLIiOATION FILED MAR.15, 1909.
929,027. Patented July 27, 1909.
`GEORGE SCHUHMANN, or READING, PENNSYLVANIA.
To alt 'whom zt 'may concern:
Be 1t known that I, GEORGE SCHUHMANN, a
Specification bf Letters Patent. Application led March 15, 1.90.9. Serial 4No. 483,448.
citizen of the United States, and a resident of l the city of Reading, in the countyv of Berks and State of Pennsylvania, have invented certain new and useful Improvements in Screw-Couplings, of whichthe followingis' a specification.
My invention relates to 'screwcouplings generally, but more particularly to those em'- ployed in connecting oil well tubingand the ke, in which the couplings are subjected to. l special strains due to the heavy weight de-.
. pending from them and lsimultaneous vibratory or jarring action,` the effects -of both of which strains are ordinarily concentrated at the end of the threads as the weakest points in the connected tubing.
'Ihe object of my invention is to provide in a simple and effective way for eliminating these points of weakness,.for supporting the screw threaded portion of the tubing so as to prevent. injurious vibrating action, and for maintaining these conditions and a uniform strain upon the couplingr sleeve notwithstanding frequent screwing and unscrewing ofthe parts.
y Couplings have heretofore been made in which the male and female members have each been provided with a vanishing thread cut to a gradually-reducing depth on a conical surface so that the bottoms of successive j convolutions lie in one tapering line while the tops of the threads lie in-a line of'different taper. 1 This construction not only involves the cutting of a s ecial form of thread upon both the male an female memberarequiring more than ordinary labor and skill to provide i a uniform contact of the threads throughout when the parts are in normal engagement, but owing to such differing tapers the repeated rescrewing together of the parts pro-- i d'uces unequally distributed strains in the coupling.
My invention consists in forming an ordinary tapering thread in the female member of the coupling, and a corresponding ordinary thread upon theconical portion of the male member gradually vanishing upon the adjoining cylindrical ortion ofthe latter` with the bottom of the t readthroughout lyingl on a straight line'parallel with the line joining the tops of the full threads; a uniform taper -of the threads upon both members belng maintained asusual, and the connecting fermented my 27, 1909.
male member being extended beyond the conical portion-of the male member so that the to s of its threads engage the vanishing .threa upon the cylindrical body of the tube, thereby reinforcingthe latter up to the uncut portion of the tube, as hereafter fully described and specifically pointed out.
The drawing is a diagrammatic cross-sectional view of a screwthreaded pipe. coupling .embodying my invention, the uniform taper of the threads being somewhat exaggerated.
. 'I he sleeve or female member a of the coupling, is provided interiorly, as /usualf with a full conical thread b, extending its full length as shown though obviously the Yunthreaded body of the sleeve may be projected beyond the threaded portion, if desired, to guard the-end of the thread as is commonly done.
T he tube end or male member c `of the coupling, is also provided as usual with a full conical thread d corresponding in form and taper with theinterior thread b of the female member; but said thread, instead of ending more orlessabruptly with the bottom of its end convolution below the c lind'rical surface .e of the body of the tube, 1s continued asa vanishing thread formed upon the cylindrical 'body of the tube until the vanishing bottom f of the thread, lying always on the straight line g parallel with the line h joining the tops of the full thread, is blended into the cylindrical surface e of the tube.
r[he threaded female member a, when screwed upon the malemember c, is adapted to effect a perfect thread-contact when. the end of the member a, is projected beyond the conical portion of the member c so as to in-v close the adjoining cylindrical portion of the tube with the to portions ofthe end convolutions of its t read engaging the vanishing thread on the cylindrical tube'body; so that the latter is rigidly supported by the female member fully up to the uncut portion thereof whereby any vibratory action upon the weakenedv thread portion is prevented; while "at the same time the full tensile strength of the unthraded'tube is retained to withstand longitudinal strains. v A single uniform taper being employed as usual upon both engaging-members, not only is a perfect engagement of` the threads strains ter how frequently the joint may be unscrewed and rescrewed; any Wear of the .threads being uniformly taken up by the l thread upon the male member, the length of thc female member is made sufficiently greater than is ordinarily required to permit of `its fully covering said vanishing thread. But my improvement involves no change in the usual size or structure of the pipe member end such as enlarging the same; or any objectionable departure from the ordinary thread-cutting operation or the thread-cutting tools commonly employed; yet it effectively secures the desired objects of maintaining the tensile strength of the pipe scction and eliminating the usual vibra'tory strains at the terminus of the thread, while insuring a uniform t of the threads how? ever frequently the connections may be screwed and unscrewed.
What I claim is:-
1. In a screw coupling a male member having a full screw thread on a conical surface vanishing on an. adjoining cylindrical surface, the'bottoms of the thread convolutions vthroughout being on a straight line parallel With the tops of the full threads.
p 2. A screw coupling comprising a male member having a full screw thread 0n a conical surface vanishing on an adjoining cylindrical surface, the bottoms of the thread convolutions throughout being on a straight 1 line parallel with the tops of the full threads, and a female member having a screw thread on a conical surface, the top portion only of which thread enga es the vanishing thread on the cylindrica surface of the male member.y
In testimony whereof, I affix my signature, in the presence of two witnesses.`
` GEORGE SCHUHMANN. Witnesses:
W. G. STEWART, D. M. STEWART.'