Ball nut and means for attaching a mounting flange thereto

A ball nut having a ball return tube is formed with an externally threaded stud for supporting a mounting flange which is adapted to be screwed onto the stud. Angularly spaced segments of resiliently compressible wire are seated in an annular groove in one face of the flange. When the flange is screwed onto the stud, the segments engage a shoulder on the nut and compress to enable the flange to be tightened to a position in which the flange is in a predetermined angular orientation relative to the ball return tube.

BACKGROUND OF THE INVENTION 
This invention relates generally to a nut and more specifically to a ball 
nut of the type which is adapted to be coupled to a ball screw by a train 
of recirculating anti-friction balls. When the nut and the screw are 
turned relative to one another, the nut advances along the screw with low 
friction by virtue of the balls circulating between the threads of the nut 
and the screw. One or more return tubes located on the outer side of the 
nut permit the balls to continuously recirculate in a closed path. 
In most instances, the screw is rotated and the nut is held in a 
rotationally stationary position. To prevent rotation of the nut, a 
mounting collar or flange is threadably coupled to the nut and is formed 
with holes for receiving fasteners which secure the nut to a machine 
element or the like adapted to be advanced by rotation of the screw. 
It is desirable to establish a predetermined angular relationship between 
the nut and the mounting flange. For example, it may be desired to locate 
the holes in the mounting flange in predetermined angular position 
relative to the ball return tubes. With conventional ball nuts, this can 
be achieved only through the use of shims of selective thickness between 
the nut and the flange or by trial-and-error assembly, disassembly, 
machining and reassembly of the nut and the flange. 
SUMMARY OF THE INVENTION 
The general aim of the present invention is to provide a new and improved 
nut in which a predetermined angular relationship between the nut and the 
mounting flange may be established faster and easier than has been 
possible heretofore. 
A more detailed object of the invention is to achieve the foregoing through 
the provision of resiliently compressible inserts between the nut and the 
mounting flange. When the flange is tightened on the nut, the inserts 
compress to permit such tightening while enabling the flange to be turned 
into a desired angular orientation relative to the nut. 
Still another object of the invention is to use the compressible inserts to 
keep the mounting flange square on the nut. 
These and other objects and advantages of the invention will become more 
apparent from the following detailed description when taken in conjunction 
with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
For purposes of illustration, the invention has been shown in the drawings 
in connection with a nut and specifically a ball nut 10 which is adapted 
to be advanced along a ball screw 11 when the latter is rotated. The ball 
nut includes a sleeve 12 whose bore is formed with a helical groove 13 
which is of the same lead as a helical groove 14 formed in the screw 11. 
In this particular instance, two trains of spherical balls 15 circulate 
within the grooves 13 and 14 when the screw 11 is rotated to advance the 
nut linearly along the screw. A return tube 16 is associated with each 
train of balls and serves to recirculate the balls from one end of the 
groove 13 in the nut 10 to the other end of the groove. It should be 
appreciated that the nut could utilize only a single train of balls and a 
single return tube. 
Each return tube 16 is located on the outer side of the sleeve 12 and its 
end portions are telescoped into holes 17 (FIG. 2) formed in the sleeve. A 
clamping strap 18 (FIG. 1) extends across the return tubes and is secured 
to the sleeve 12 by means of screws 19 extending through the strap and 
threaded into tapped holes 20 (FIG. 2) in the sleeve. The end portions of 
the strap are received in a longitudinally extending groove 21 formed in 
the outer side of the sleeve. 
The nut 10 is adapted to be secured to a member such as a machine tool 
carriage 20 which is adapted to be advanced when the screw 11 is rotated. 
For this purpose, the nut includes a mounting collar or flange 25 adapted 
to be secured to the sleeve 12 and fastened to the carriage 20. To couple 
the sleeve and the flange, a stud 26 with external threads 27 is formed 
integrally with and projects axially from the sleeve. The sleeve is formed 
with a central bore having internal threads 28 adapted to be screwed onto 
the threads of the stud. The outer diameter of the stud 26 is less than 
the outer diameter of the sleeve 12 and thus an axially facing and 
radially outwardly extending shoulder 30 (FIG. 2) is defined at the 
junction of the sleeve and the stud. When the mounting flange 25 is 
screwed onto the stud 26, one end of the flange is located closely 
adjacent the shoulder 30. 
Herein, the mounting flange 25 is square in shape and its corners are 
formed with holes 31. Fasteners in the form of screws 32 (FIG. 1) extend 
through the holes and are threaded into tapped holes 33 in the carriage 20 
in order to secure the flange to the carriage. 
In certain cases, it is necessary that the holes 31 or other element on the 
square mounting flange 25 be located in a predetermined angular 
orientation with respect to an element on the sleeve 12 when the flange is 
tightened fully on the stud 26. By way of example, structure surrounding 
the ball screw 11 may dictate that the nut 10 be installed on the screw 
with the return tubes 16 located in a specific angular position. To 
achieve such an installation, it is necessary that the mounting flange 25 
be located on the stud 26 in a predetermined angular orientation when the 
flange is fully tight. 
According to the present invention, resiliently compressible means 35 are 
provided between the sleeve 12 and the flange 25 to enable the flange to 
be screwed tightly onto the stud 26 and still be located in an exact 
predetermined angular orientation relative to the sleeve. As a result, the 
need for trial-and-error machining and the use of shims of selective 
thickness may be completely avoided. 
More specifically, the resiliently compressible means 35 are ring-like in 
nature and preferably are formed by three angularly spaced arcuate inserts 
or segments (see FIG. 3). Herein, each segment is formed from a piece of 
round wire which may be steel, copper, aluminum, plastic or other material 
capable of being resiliently compressed. 
As shown most clearly in FIGS. 3 and 4, the three wire segments 35 are 
located in and are spaced around an annular groove 36 of generally 
V-shaped cross-section. Herein, the groove is formed in that end of the 
flange 25 disposed in face-to-face relation with the shoulder 30. The 
depth and shape of the groove are such that a portion of each wire segment 
projects axially beyond the end of the flange (see FIG. 4). 
The wire segments 35 are captivated in the groove 36 so as to be held in 
assembled relation with the flange 25 until such time as the flange is 
screwed onto the stud 26. In the preferred embodiment, the segments are 
staked in place in the groove by striking the center of each segment at 37 
with a round punch having a diameter equal approximately to that of the 
wire. Such punching causes a portion of each segment 35 to flow and be 
pressed tightly against the walls of the groove 37 so as to captivate the 
segment in the groove. 
With the foregoing arrangement, the flange 25 is screwed onto the stud 26 
until the segments 35 contact the shoulder 30. At this point, the flange 
starts to tighten on the stud. If the flange is not then in proper angular 
orientation with the sleeve 12, the flange may be turned further. During 
such turning, the segments 35 compress to prevent the flange from locking 
up on the stud. By virtue thereof, the flange may be turned through the 
angular distance necessary to establish the proper orientation. After the 
flange has been properly oriented, it may be pinned in place by driving a 
pin (not shown) through a hole 40 (FIG. 3) in the flange. 
The segments 35 not only enable continued turning of the flange 25 after 
tightening but also help hold the flange in a square condition on the stud 
26. By virtue of their resiliency, the compressed segments 35 urge the 
flange away from the shoulder 30. As a result, the right flanks of the 
thread 28 in the flange are loaded in continuous contact with the left 
flanks of the thread 27 on the stud 26. This provides alinement of the 
flange to the threads to permit close control of the flange squareness 
relative to the axis of the nut 10 without need of additional machining 
operations. In addition, such engagement of the threads helps keep the 
flange square to the nut during service use.