Apparatus for providing tubing with at least one internal spinal fin

Multi-stage ball bearing assembly mounted internally of a floating plug or the forward end of a mandrel and including a plurality of axially aligned ball bearings for enabling rotation of a spinner for forming at least two internal spiral grooves in the inner portion of tubing upon relative motion therebetween to produce at least one spiral fin internally of the tubing. The ball bearings include inner and outer ball tracks and a plurality of spherical balls which roll between the tracks. Predetermined ones of the outer ball tracks are displaced axially with respect to the inner ball tracks in the same direction as the relative movement between the tubing and the spinner to provide relief space in the direction of relative movement which, upon rotation being imparted to the spinner which in turn imparts rotation load to the multi-stage ball bearing assembly in the same direction of such relative movement, causes the rotation load to be distributed substantially equally between the ball bearings.

BACKGROUND OF THE INVENTION 
This invention relates generally to new and improved apparatus for 
providing the internal portion of tubing with at least one internal spiral 
fin and more particularly is an improvement of the invention disclosed in 
U.S. Pat. No. 4,702,096 issued Oct. 27, 1987 to Francis J. Fuchs, Jr., 
entitled APATUS AND PROCESS FOR PROVIDING TUBING WITH AT LEAST ONE 
INTERNAL SPIRAL GROOVE OR FIN; this patent is hereby incorporated herein 
by reference as if fully set forth herein and will be referred to 
hereinafter as the "Fuchs '096 Patent." Accordingly, it will be understood 
that the apparatus of this invention is for the same purpose as the 
apparatus disclosed in the Fuchs '096 Patent and for overcoming the same 
prior art problems taught in the BACKGROUND OF THE INVENTION of the Fuchs 
'096 Patent. 
As will be better understood from the detailed description of the present 
invention set forth below, the apparatus of the present invention is 
shorter and more compact than the apparatus of the Fuchs '096 Patent, 
particularly that shown in FIGS. 7 and 8, and unlike the apparatus of the 
Fuchs '096 Patent the multi-stage ball bearing assembly of the present 
invention extends inwardly of, instead of outwardly from, the floating 
plug or forward portion of the mandrel to which the assembly is mounted 
thereby making the assembly less subject to damage and axial misalignment. 
Also, it has been found that mounting the multi-stage ball bearing 
assembly inwardly of the floating plug or forward portion of the mandrel 
makes the removal and replacement of the spinner easier, less time 
consuming and therefore more efficient to maintain. 
SUMMARY OF THE INVENTION 
Multi-stage ball bearing assembly mounted internally of a floating plug or 
the forward end of a mandrel and including a plurality of axially aligned 
ball bearings for enabling rotation of a spinner for forming at least two 
internal spiral grooves in the inner portion of tubing upon relative 
motion therebetween to produce at least one spiral fin internally of the 
tubing. The ball bearings include inner and outer ball tracks and a 
plurality of spherical balls which roll between the tracks. Predetermined 
ones of the outer ball tracks are displaced axially with respect to the 
inner ball tracks in the same direction as the relative movement between 
the tubing and the spinner to provide relief space in the direction of 
relative movement which, upon rotation being imparted to the spinner which 
in turn imparts rotation load to the multi-stage ball bearing assembly in 
the same direction of such relative movement, causes the rotation load to 
be distributed substantially equally between the ball bearings.

DESCRIPTION OF THE DRAWING 
FIG. 1 is a side elevational view of a multi-stage ball bearing assembly 
embodying the present invention; the view is a horizonally split view with 
the upper portion being shown generally in cross-section and with the 
lower portion being shown in solid outline. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
As noted above, the present invention is an improvement of apparatus 
disclosed in Fuchs '096 Patent and more particularly it will be understood 
that the apparatus shown in FIG. 1 is an improvement of the apparatus 
shown in FIGS. 7 and 8 of the Fuchs '096 Patent. It will be further 
understood that the apparatus shown in FIG. 1 may be mounted on the end of 
a floating plug such as floating plug 38 shown in FIG. 4 of the Fuchs '096 
Patent for utilization with the draw die 32 and draw blocks 42 also 
illustrated in FIG. 4 of the Fuchs '096 Patent to produce tubing provided 
with at least one internal spiral fin. Still further, it will be 
understood that the apparatus shown in FIG. 1 may be mounted on the 
forward portion of a mandrel embodied in a continuous extrusion apparatus 
for continuously producing tubing provided with at least one internal 
spiral fin and may be, for example, mounted in a recess provided in the 
forward portion of the mandrel 149 for utilization with the continuous 
extrusion apparatus 140 both shown in FIG. 10 of the Fuchs '096 Patent. 
Accordingly, for convenience of reference and comparative understanding of 
the differences between the present invention and the structure disclosed 
in FIGS. 4, 7 and 8 of the Fuchs '096 Patent, structure shown in FIG. 1 
corresponding to structure shown in FIGS. 4, 7 and 8 of the Fuchs '096 
Patent will be given corresponding numerical designations incremented by 
200 except for the spinner 34 which will be given the same numerical 
designation. 
Referring then to FIG. 1, apparatus embodying the present improvement 
invention may include a floating plug indicated by general numerical 
designation 238, spinner 34 mounted on shaft 266 for rotation therewith 
and a multi-stage ball bearing assembly indicated by general numerical 
designation 260 mounted internally of the floating plug 238 and including 
a plurality of axially aligned ball bearings indicated, respectively, by 
general numerical designations 261-267. The assembly 260 further includes 
a a plurality of axially displaced, radially inwardly extending spherical 
grooves 291-297. The assembly 260 further includes a plurality of axially 
aligned, generally annular, cup-shaped members 271-277 provided, 
respectively, with inwardly extending recesses 281-287 extending axially 
in the forward direction indicated by the arrow 290 shown at the top of 
FIG. 1. [As in the Fuchs '096 Patent, the expression "forward direction" 
as used herein refers to the direction of the relative movement of the 
tubing (e.g. tubing 10A shown in FIG. 4 of the Fuchs '096 Patent moving in 
the "forward direction" as indicated by the arrow 44 of such FIG. 4) with 
respect to the spinner during groove, grooves, or fin forming in the 
tubing internal portion, and the expression "rearward direction" refers to 
the direction opposite to the "forward direction"; it will be understood 
that the spinner may be stationary and the tubing moved, or the tubing may 
be stationary and the spinner moved, or each may be moved, but the 
significant consideration is the "relevant" direction of movement of the 
tubing with respect to the spinner.] The recesses 281-287 formed in the 
cups 271-277 provide outer ball tracks and the grooves 291-297 formed in 
the shaft 266 provide inner ball tracks between which roll spherical balls 
201-207. 
In accordance with the further teachings of the present improvement 
invention, and referring still to FIG. 1, it will be noted that the outer 
ball tracks comprised of the recesses 281-287 formed in cups 271-277 are 
displaced axially in the forward direction with respect to the inner ball 
tracks comprised of the grooves 291-297. This axial displacement provides 
relief space between the spherical balls and the outer tracks in the 
forward direction with such relief space being indicated by way of example 
by the arrows 208 and 209 shown in the upward portion of FIG. 1 indicating 
the axial relief space between the spherical ball 207 and the recess 287 
in the forward direction. In accordance with the still further particular 
aspects of the present improvement invention, it will be further 
understood as noted from FIG. 1 that successive ones of the outer ball 
tracks are displaced axially with respect to the inner ball tracks 
increasingly greater distances in the forward direction (direction 
indicated by arrow 290) to provide increasingly greater relief space in 
the forward direction between the outer ball tracks and the spherical 
balls which roll therein to cause the plurality of bearings 261-267 to 
assume a rotation load, indicated by the enlarged arrow 299, imparted to 
the multi-stage ball bearing assembly 260 by the spinner 34 during fin 
forming, sequentially and successively in the forward direction whereby 
the rotation load is assumed equally, or substantially equally, by each 
ball bearing; this rotation load distribution is taught in detail in the 
Fuchs '096 Patent beginning at Column 4, line 27 and being illustrated in 
FIGS. 7 and 8 of the Fuchs '096 Patent although it will be expressly 
understood that the assumption of the rotation load by the ball bearings 
261-267 of the present invention is assumed sequentially and successively 
from the forward direction and opposite to the assumption of the 
sequential and successive load assumption by the ball bearings 61-65 shown 
in FIGS. 7 and 8 of the Fuchs '096 Patent which assume the rotation load 
in the rearward direction (right to left as viewed in FIGS. 7 and 8 of the 
Fuchs '096 Patent). Accordingly, it will be further understood that upon 
rotation load being imparted to the multi-stage ball bearing assembly 260 
by the rotating spinner 34, the ball bearings 261-267 of the assembly 260 
will assume the rotation load sequentially and successively in the forward 
direction due to the displacement of the outer ball tracks axially in the 
forward direction with respect to the inner ball tracks in increasingly 
greater axial amounts as illustrated in FIG. 1. 
The multi-stage ball bearing assembly 260 may be provided with a second 
plurality of axially aligned ball bearings indicated, respectively, by 
general numerical designations 321-323. This second plurality of ball 
bearings accommodates a rotation load imparted to the multi-stage ball 
bearing assembly 260 acting in the rearward direction or in the direction 
opposite to the rotation load indicated by the arrow 299 and referred to 
above. Such rearwardly acting rotation load could occur, for example, upon 
a stoppage or jam in the groove forming by the spinner 34 into the 
internal portion of the tubing caused, for example, by the spinner 
striking an unusually hard portion of the tubing. To clear the stoppage or 
jammed condition, it could be necessary to produce relative movement 
between the spinner 34 and the tubing in the rearward direction by 
imparting rearwardly acting force to the tubing and/or spinner which 
rearwardly acting force could impart rotation to the spinner and hence 
impart the rotation load acting in the rearward direction or in the 
direction opposite to the direction indicated by the arrow 299. The 
plurality of axially aligned ball bearings 321-323 may be comprised of a 
second plurality of axially displaced, radially inwardly extending 
spherical grooves 314-316 formed in the rearward portion of the shaft 266 
as shown in FIG. 1, a second plurality of axially aligned generally 
annular cup-shaped members 325-327 provided, respectively, with inwardly 
extending recesses 331-333 extending axially in the rearward direction. 
The recesses 331-333 formed in the cups 325-327 provide outer ball tracks, 
and the grooves 314-316 formed in the shaft 266 provide inner ball tracks 
between which roll spherical balls 336-338. In the preferred embodiment of 
the present invention, the recesses 331-333 are aligned axially with, and 
not axially displaced from, the inwardly extending grooves 314-316; 
however, if it is desired for the bearings 321-323 to sequentially assume 
the rotation load acting in the rearward direction the outer ball tracks 
provided by the recesses 331-333 may be displaced axially with respect to 
the inner ball tracks provided by the spherical grooves 314-316 
increasingly greater distances in the forward direction (direction of the 
arrow 290) to cause the bearings 321-323 to assume the rearward acting 
rotation load sequentially and successively in the forward direction 
(direction of arrow 290). 
As to the detailed structure of the floating plug indicated by general 
numerical designation 238 as shown in the embodiment of FIG. 1, it will be 
understood that the floating plug 238 may include a generally cylindrical, 
hollow outer member 300, a forward generally annular member 302, a forward 
generally annular seating member 304 provided with a central aperture 306 
for surrounding the forward portion of the shaft 266 and provided with 
external threads for threadedly engaging internal threads provided on the 
forward portion of the cylindrical member 300 to seat and mount the 
forward annular member 302 to the cylindrical member 300, and a rearward 
seating generally annular seating member 308 for seating and mounting the 
pluralities of generally cup-shaped annular members 261-267 and 321-323 to 
the cylindrical member 300 and thereby through the pluralities of 
spherical balls 201-207 and 336-338, the shaft 266 rotatably internally of 
the cylindrical member 300, the annular seating member 308 is provided 
with external threads for threadedly engaging internal threads provided 
internally of the rearward portion of the cylindrical member 300 as shown 
in FIG. 1; alternatively the seating member 308 could be a solid 
cylindrical plug-like member for also closing the rearward portion of the 
floating plug 238. It will be further understood that in assembly the 
pluralities of spherical balls 201-207 and 336-338 and the pluralities of 
generally annular cup-shaped members 271-277 and 325-327 are assembled to 
the shaft 266 and thereafter inserted into the cylidnrical member 300 from 
the rear after which the annular seating member 308 is threadedly engaged 
into the rearward portion of the cylindrical member 300; the spinner 34 is 
then inserted over the reduced diameter forward portion of the shaft 266 
and mounted for rotation with the shaft by a nut 310 and intermediate 
washer or spacer 312; the forward external portion of the shaft 266 is 
threaded as shown for threaded engagement by the internal threads provided 
on the nut 310. It has been discovered that by making the outer 
cylindrical member 300 and the annular member 302 in two pieces an economy 
and efficiency can be achieved; namely, since the outer cylindrical member 
300 experiences less wear than the forward annular member 302 upon the 
tubing (e.g. tubing 14A shown in FIG. 4 of the Fuchs '096 Patent) passing 
thereover during groove and fin forming by the spinner 34, the larger 
outer cylindrical member 300 may be made of less expensive tool steel and 
the smaller forward annular member 302 may be made of the more expensive 
and more wear resistant tungsten carbide. 
It will be understood by those skilled in the art that many variations and 
modifications may be made in the present invention without departing from 
the spirit and the scope thereof.