Split frame portable machining lathe

The present invention is a lathe 10 having a stationary member 11 and a rotating gear member 15. A circular race member 23 is connected to the gear member 15 and held in position by means of bearings 17 and 19. Preferably, the bearings 17 and 19 have longitudinal axes perpendicular to the top surface of the stationary member 11. Further, mounting brackets 35 are utilized to quickly and easily mount a motor 70 onto the stationary member 11. A two part tool module 38 is also disclosed.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to a machining lathe, and more 
specifically to a split frame clamshell type portable machining lathe. 
2. Description of the Prior Art 
The general concept of a split frame clamshell type portable machining 
lathe is known in the art. However, the prior art machining lathes have 
several disadvantages associated with them. The prior art machining lathes 
to date have had a race member that is an integral part of the gear 
member. It is a common occurrence for a bearing to fail. When the bearing 
fails and the race member is an integral part of the gear member, 
substantial damage is done to the entire lathe and it is a very expensive 
procedure to replace the damaged parts. 
In addition, in prior art lathes, the race member is guided in its circular 
path by two sets of bearings that have their longitudinal axis generally 
perpendicular to each other. 
The portable machining lathes are often used in an environment, such as in 
a nuclear reactor plant, where it is of the utmost importance to minimize 
the amount of time that the operator is on the job site. By minimizing the 
amount of time, the amount of radiation that the operator receives is 
reduced. The tool block which contains the cutting tool is often secured 
to the gear member by a plurality of screws. When the tool bit itself 
breaks or some other portion of the tool block malfunctions, it is 
necessary to replace the entire tool module, which takes a substantial 
amount of time. In addition, to date the drive means for the machining 
lathes have also been mounted directly to the stationary member of the 
machining lathe. Therefore, when attaching or taking off the drive means, 
it is necessary to either completely insert or completely take out a 
plurality of screws. This too is a relatively time-consuming process. 
The present invention addresses the problems associated with the prior art 
devices and provides for a new and improved split frame portable machining 
lathe. The present invention provides for a replaceable race member, a 
unique bearing arrangement as well as time saving replaceable tool block 
modules and drive mean mounts. 
SUMMARY OF THE INVENTION 
The present invention is a split-frame portable machining lathe for 
machining a workpiece. The lathe includes a stationary member having first 
and second generally semi-circular sections cooperatively connected. The 
stationary member has a top surface, inner sidewall and outer sidewall. 
Also provided is a means for securing the stationary member to the 
workpiece. A gear member has first and second generally semi-circular 
sections cooperatively connected. A first set of bearings cooperatively 
connected to the top surface of the stationary member proximate the inner 
sidewall is provided. A second set of bearings cooperatively connected to 
the top surface of this stationary member proximate the outer sidewall is 
also provided, whereby a circular path is defined between the first and 
second sets of bearings. A circular race member having first and second 
semi-circular race sections is cooperatively connected to the gear member, 
whereby the race member rotates in the circular path. In one embodiment, 
the race sections are removably connected to the first and second gear 
sections respectively. Another feature of the present invention is that 
the first set of bearings have longitudinal axes which are generally 
perpendicular to the top surface of the stationary member and the second 
set of bearings have longitudinal axes which are generally perpendicular 
to the top surface of the stationary member. 
Another feature of the present invention is that the outer edge of the 
stationary member defines a slot having a first edge and a second edge for 
receiving a motor mounting bracket. First and second mounting holes are 
defined adjacent both the first edge and the second edge. The mounting 
bracket has a base member sized to be accommodated in the slot and the 
mounting bracket has first and second flange sections. There are also 
first and second mounting strips, wherein the first strip overlies both 
the first mounting hole and the first flange and the second strip overlies 
both the second mounting hole and the second flange. Means for releasably 
cooperatively connecting the mounting strips to the mounting holes are 
provided. Still another feature of the present invention includes a tool 
module having a tool block cooperatively connected to the gear member, the 
tool block defining a slot. A tool block slide is adapted to be slid into 
the slot. The tool block slide has an opening for receiving a tool bit. 
Means for effecting movement of the tool block slide and also means for 
cooperatively connecting the tool block slide to the tool block are 
provided. The cooperatively connecting means comprises a mounting bar 
connected to the tool block slide and the mounting bar being secured to 
the tool block by means of a screw, or other fastening means, through the 
mounting bar into a bore in the tool block.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to the Figures, wherein like numerals represent like parts 
throughout the several views, there is generally illustrated at 10 a split 
frame portable machining lathe. The lathe 10 includes a stationary member 
11 having a first generally semi-circular section 11a and a second 
generally semi-circular section 11b cooperatively connected to form the 
stationary member 11. The first stationary section 11a has a top surface 
11c, inner sidewall 11d and an outer sidewall 11e. The second stationary 
section 11b has a top surface 11f, inner sidewall 11g and outer sidewall 
11h. When cooperatively connected, the top surfaces 11c and 11f form the 
top surface of the stationary member, the inner sidewalls 11d and 11g form 
the inner sidewall of the stationary member and the outer sidewalls 11e 
and 11h form the outer sidewall of the stationary member. The first and 
second sections 11a and 11b may be cooperatively connected by means well 
known in the art. Generally illustrated in FIG. 1 is a swingable bolt 12 
which is swingably mounted to the second stationary section 11b. When the 
two sections 11a and 11b are brought together, the bolt is swung into the 
opening 13 of the first stationary section 11a and the nut 14 is tightened 
against the edges 11k to cooperatively connect the two sections 11a and 
11b. Typically, two such swingable bolts 12 and nuts 14 are utilized to 
cooperatively connect the two sections 11a and 11b the second being 
180.degree. from the first. 
A gear member 15 has a first generally semi-circular gear section 15a 
cooperatively connected to a second generally circular section 15b. The 
configuration of the second gear section 15b is most clearly shown in FIG. 
3, the configuration of the first gear section 15a being similar. The gear 
section 15b has a gear tooth portion 15c that extends around the outer 
periphery of the second gear section 15b. Similarly, the first gear 
section 15a has a gear tooth portions 15d around its outer periphery and, 
when assembled, the gear tooth portions 15d and 15c form a continuous gear 
tooth. The gear sections 15a and 15b have a top surface 15e and 15f, 
respectively. The upper surfaces 15g and 15h of the gear tooth portions 
15d and 15c, respectively, are spaced slightly below the top surfaces 15e 
and 15f, respectively. 
The second gear section 15b has an inner cavity 16. While not shown, the 
first gear section 15a has a similar inner cavity. A first set of roller 
bearings 17 are cooperatively connected to the top surface 11f of the 
stationary section 11a by means of bolts 18. The roller bearings 17 are 
cooperatively connected around the inner periphery of both the first 
stationary section 11a and second stationary section 11b in the 
configuration of a circle. The bearings 17 rotate along a longitudinal 
axis which coincides with the longitudinal axis of the bolts 18 and is 
generally perpendicular to the top surface 11f. A second set of bearings 
19 are cooperatively connected to the top surface 11f of the stationary 
section 11b proximate the outer sidewall 11h. The bearings 19 are 
cooperatively connected around the outer perimeter of the stationary 
sections 11b and 11a by any suitable means such as bolts 20. A shim 21, in 
the general shape of a washer, may be placed between the bearing 19 and 
the upper surface 11 f to adjust the clearance between the bearings 19 and 
the race member. The second set of bearings 19 are similarly positioned to 
form a circular path around the outer perimeters of both of the stationary 
sections 11a and 11b. A circular path is defined between the first set of 
bearings 17 and the second set of bearings 19. The bearings 19 rotate on a 
longitudinal axis which is overlies the longitudinal axis of the bolt 20 
and is generally perpendicular to the top surface 11f. Preferably, the 
bearing 19 has a V-shaped groove 22 which extends around the circumference 
of the bearing 19. The V-shaped groove 22 is formed by the surfaces 22a 
and 22b. Preferably, the outer surface of the bearing 19 also has a top 
inwardly slanted surface 22c and a bottom inwardly slanted surface 22d to 
give the overall outer appearance of a generally W-shaped surface. 
A circular race member 23 has a first semi-circular race section 23b 
section 23a and a second semi-circular race section 23b cooperatively 
connected to the gear sections 15a and 15b respectively. A race member 23b 
is releaseably and cooperatively connected to the second gear section 15b 
by means of a plurality of bolts 24 through a plurality of holes 23c in 
the race section 23b. The inner cavity 16 has a notch 16a having the same 
configuration as the top section of the race section 23a. This further 
stabilizes the race section 23a. The race section 23a is semi-circular. A 
similar race section 23a is cooperatively connected in the same manner to 
the first gear section 15a. A cross-section through the first stationary 
section 11a and first gear section 15a, at a point 180.degree. from 
section lines 2--2 would appear identical to the cross-section shown in 
FIG. 2. The inner cavity 16 also has a clearance opening 16b to provide 
clearance over the head of the bolt 20. A similar opening 16c is provided 
for clearance over the roller bearings 17. 
When looking at a cross-section, as in FIG. 3, the race sections have an 
inner sidewall 25 which is straight. The outer sidewall 26 has a surface 
configuration which mates with the V-shaped groove 22 of the bearing 19 
and preferably with the entire W-shaped configuration of the bearing 19. 
As the race sections rotate the inner sidewall 25 bears against the roller 
bearings 17 and the outer sidewall 26 bears against the bearings 19. 
Another feature of the present invention is a means for rapidly connecting 
a drive means, or motor, 70 to the lathe 10. The motor 70 may be one of 
any number of motors which are suitable for this purpose. Such motors 
would include air motors and hydraulic motors which are well-known in the 
art. The motors may also be straight back, reversible, or right angled 
motors as are also well-known in the art. The drive motor 70 has a gear 
70a which, when the motor is in place, engages the gear teeth of the gear 
member 15. Covers 27a and 27b are secured around the gear sections 15a and 
15b respectively by means of screws 28, or other suitable fastening means. 
The covers have a hood protrusion 27c which is sized to extend away from 
the gear teeth and cover the gear 70a of the motor 70. 
FIG. 5 shows the bracket 29 to which the motor 70 is mounted. The bracket 
29 has a base member 30 that has a planar bottom surface. At the top end 
of the base member 30, a cover 31 is cooperatively connected thereto. An 
opening 31c is provided in the cover 31 to allow for the gear 70a to be 
inserted into the opening 31c. A plurality of mounting holes 31d are 
provided in the cover 31. Screws, or other suitable fastening means, are 
inserted through the holes 31d and into the motor 70, thereby fastening 
the motor 70 to the bracket 29. The base member 30 has two bars 32 
extending the length of the base member 30, thereby defining a first 
flange area 32a and a second flange area 32b. The flange areas are 
parallel to the planar bottom of the base member 30. 
Areas for accepting the bracket 29 are located at various points around the 
stationary member 11. Preferably, four such areas are provided. As shown 
in FIG. 1, two areas are shown on the first stationary section 11a and, 
not shown, two similar areas may be provided on the second stationary 
section 11b. Along the outer sidewall 11e and 11h are slots 33 having a 
generally planar back 33a. The slot 33 has a first edge 33b and a second 
edge 33c. The edges 33b and 33c are parallel to each other. The depth of 
the slot, measured from the outer sidewall 11e to the back 33a is equal to 
the thickness of the base member 30 of the bracket 29. The width of the 
slot 33 is also equal to the width of the base member 30 and the height of 
the slot 33 is equal to the height of the base member 30. Accordingly, the 
base member 30 is sized to be accommodated in the slot 33. Adjacent the 
first edge 33b and second edge 33c on the outer sidewall 11e are a 
plurality of mounting holes 34. Mounting brackets 35, of a general 
rectangular shape, are utilized. The mounting brackets 35 have mounting 
holes 36 which are in alignment with the mounting holes 34. When the 
bracket 30 is slid into the slot 33, the mounting brackets 35 are placed 
over the mounting holes 34 and screws 37 are inserted through the holes 36 
and 34. The mounting brackets are aligned over the mounting holes 34 and 
also extends over the flange areas 32a and 32b to secure the bracket 29, 
and hence the motor 70, to the lathe 10. To replace a motor 70, it is only 
necessary to unloosen the screws 37 and the bracket 29 may be slid out of 
the slot 33 while the mounting brackets 35 are loosely held in place. A 
new motor, with mounting bracket 29, may then be slid into the slot 33 and 
the screws 37 tightened to securely fasten the motor 70 to the lathe 10. 
It is not necessary to completely remove the screws to replace the motor 
70. 
An exploded perspective view of a tool module, generally designated as 38, 
is shown in FIG. 4. The tool module 38 includes a tool block 39 having a 
base member 39a that has a planar bottom surface. The planar bottom 
surface rests on and is cooperatively connected to the top surface of the 
gear member 15. The tool block 39 also has a first sidewall member 39b 
cooperatively connected to the base member 39a and a second sidewall 
member 39c cooperatively connected to the base member 39a. Preferably, the 
base member 39a, first sidewall 39b and second sidewall 39c are a single 
integral piece. The first sidewall member 39b has a first groove 39d 
formed by the downwardly sloping surface 39e and the planar surface 39f. 
The planar surface 39f is generally parallel to the bottom surface of the 
base member 39a. The first sidewall 39b has a planar top surface 39g. A 
plurality of mounting holes 40 extend from the top surface 39g completely 
through the base member 39a. Similarly, mounting holes 41 are formed on 
the top surface 39f and extend through the base member 39a. The planar 
surface 39h extends inward from the second sidewall 39c and has a 
plurality of mounting holes 42 that extend through the base member 39a. 
Set screw holes 43 are formed in the second sidewall 39c and extend 
through the sidewall 39c. An adjustable gib member 44 is positioned 
between the inside of the second sidewall 39b and on top of the surface 
39h. The outer sidewall 44a of the gib member 44 extends the length of the 
second sidewall 39c and its bottom 44b lies on the top surface of the base 
member 39a. A plurality of mounting holes 45 are formed in the adjustable 
gib member 44 and extends through the gib member 44. Underneath the gib 
member 44 are additional mounting holes (not shown) that extend through 
the base member 39a and are underlying the mounting holes 45. The tool 
block 39 is fastened to the gear member 15 by means of screws 46 which 
extend through the mounting holes 40, 41 and 42 and into holes in the gear 
box 15 (not shown). The mounting holes in the gear member 15 are typically 
midway between the ends of the sections 15a and 15b. The adjustable gib 
member 44 is fastened to the base member 39a by means of screws 47 which 
extend through the mounting holes 45. The screws 47 also extend through 
the underlying holes in the base member 39a and extend to and are fastened 
in the mounting holes formed in the gear member 15. The gib member 44 has 
a downwardly and inwardly sloping inner sidewall 44c which, in conjunction 
with the surface 39h forms a second groove 48. The surfaces 39f and 39h, 
along with the surface 39e and inner sidewall 44c form a slot in the tool 
block 39. The adjustable gib member 44 allows for the overall size of the 
slot to be adjusted to accommodate for wear that may take place as the 
lathe 10 is being used. Set screws 49 may be inserted through the holes 43 
to move the gib member 44 in a direction toward the first sidewall 39b to 
allow for wear. 
A tool block slide 50 has a top portion 50a cooperatively connected to a 
bottom portion 50b. One suitable means of cooperatively connecting the top 
portion 50a to the bottom portion 50b is by means of screws 51 which 
extend through the top portion 50a into the bottom portion 50b. The holes 
52 through which the screws 51 extend are shown in FIG. 4 as not having 
screws. However, when completely assembled, these holes would also have 
screws to connect the top portion 50a to the bottom portion 50b. The 
bottom portion 50b has an opening 53 which is sized to accommodate a tool 
bit 54. The tool bit 54 is sized so it may be easily slid into the opening 
53 and secured into the opening 53 by means of screws 55 which extend 
through the top portion 50a and would engage the tool bit 54. The tool 
block slide bottom 50b has a dove tailed base member 50c which is 
configured and adapted to be slid into the slot of the tool block 39 
defined by the grooves 39d and 48. The base 50c has a recess 50d formed 
therein. 
A block 56 is cooperatively connected inside of the recess 50d, by means 
well-known in the art, such as insertion in a counter bored hole. The 
block 56 has a threaded bore through which a threaded shaft 57 is 
positioned. Attached to a first end of the shaft 57 is star gear 58. A 
mounting clip 59 has a central opening through which the shaft 57 is 
positioned. The central opening is sized sufficiently to allow the shaft 
to freely rotate. The mounting clip has two mounting holes 59a. The tool 
block slide 50 is slid in position in the tool block 39 and fastened to 
the tool block by means of two screws 60 which extend through the holes 
59a and fasten into the tool block 30 into the mounting holes 39k in the 
base member 39a of the tool block 39. 
The lathe 10 is cooperatively connected to the work piece or pipe that is 
to be worked on by means of a plurality of locater pads 60. The locater 
pads 60 have a planar, rectangular engaging surface that contacts the 
workpiece. The locater pads 60 are shown in FIG. 1 in their recessed 
position. The locater pads 60 are supported through the stationary member 
11 by means of a threaded shaft which is connected at the other end to an 
adjusting knob 61. The adjusting knob is rotated which causes the shaft to 
rotate and also therefore advances the locater pad 60 inward toward the 
workpiece. Typically, six locater pads 60 are utilized for a lathe 10. 
Three locater pads are on each half section of the lathe 10. Further, the 
locater pads on one section are opposite a locater pad on the other 
section. That is, if the opposing locater pads were connected by an 
imaginary line, it would be on a diameter of the lathe 10. 
In operation, the lathe 10 is brought to the job site and is in a 
disassembled configuration. In the disassembled configuration, the first 
gear section 15a is in position over the stationary section 11a and is 
held in position by means of the bearings 17 and 19. Initially, to 
assemble the gear section 15a to the stationary section 11a, one end of 
the race section 23a is inserted between the bearings 17 and 19 and the 
entire gear section 15a is fed between the pulleys 17 and 19 until the 
gear section 15a overlies the stationary section 11a. The second gear 
section 15b is similarly initially assembled over the second stationary 
member 11b. The two sections are then assembled around a workpiece and the 
two semi-circular sections are brought together and assembled by means of 
the swingable bolts 12 and nuts 14. Further, the gear sections 15a and 15b 
are cooperatively connected by means of two hooks 62 and pins 63. The hook 
62 is swingably mounted to the top of one gear section with the pin 63 
connected to the top surface of the other gear section. The hook is then 
simply swung around the pin 63 to secure the two gear sections in 
position. Once the lathe 10 is in place, it can be accurately aligned and 
held in position by advancing the locater pads 60 toward the workpiece. A 
dial indicator may be used to accurately measure the distance from the 
center line of the workpiece. Once the lathe 10 is in position, it may 
then be secured by further tightening all of the locater pads. 
Prior to the bringing of the lathe 10 into the work area, the mounting 
brackets 35 have been loosely connected to the stationary member 11 by 
means of the screws 37. Then, when it is desired to connect the motor 70 
to the lathe 10, it is only necessary that the bracket 29, with the motor 
attached thereto, be inserted into the slot 33 and the screws 37 
tightened. Upon activation of the motor 70, the gear 70a begins to rotate 
and meshes with the gear teeth of the gear member 15, thereby causing 
rotation of the gear member 15. If it becomes necessary to replace a motor 
during the machining of a workpiece, it is only necessary that the screws 
37 be unloosened and the bracket 29 is slipped out of the slot 33 with the 
mounting brackets 35 still loosely held in place. 
The rotation of the gear member 15 causes the rotation of the race member 
23 which is cooperatively connected to the gear member 15. The bearings 17 
and 19 guide the race member 23 around its circular path. The roller 
bearings 17 in conjunction with the V bearings, or guide wheels, 19 define 
the circular path in which the race member 23 rotates. The roller bearings 
17 provide additional support, minimizing elliptical surfaces caused by 
extreme cutting loads. The gear member 15 is therefore free to rotate 
around and on the stationary member 11. 
The tool module 38, has previously been assembled to the gear member 15 as 
previously described. The tool bit 54 had been secured in the opening 53 
and firmly secured in position by the screws 55. As the gear member 15 
rotates, the tool block 39 is carried with the gear member 15. Upon each 
complete revolution, the star gear 58 strikes a feed pin positioned in the 
housing 64. A handle 65 allows for the feed pin to be in an engaged or 
disengaged position. The operation and construction of the feed pin and 
housing is well known in the art. Upon striking of the gear pin, the star 
gear rotates, thereby causing rotation of the shaft 57 inside of the block 
56. Since a block 56 is secured to the tool block slide 50, the rotation 
of the shaft 57 causes an advancing movement of the tool block slide 50. 
The advancement of the tool block slide 50 of course carries with it the 
advancement of the tool bit 54. It is understood that by suitable gear 
arrangements, the tool bit 54 may be caused to move in an up and down 
direction, as well as the in and out direction that would be caused by the 
module 38 shown in the figures. If the tool bit 54, shaft 57 or star gear 
58 would be damaged, it is only necessary for the two screws 60 to be 
unloosened and the entire tool block slide 50 slid out from the tool block 
39. A new tool block slide 50 may then be reinserted quickly and easily 
into the tool block 39 without changing the alignment of the tool block 39 
on the gear member 15. It is therefore much quicker to change a tool bit 
due to the two part construction of the tool module 38 as the tool block 
39 is always attached to the gear member 15 and it is only necessary to 
replace the tool block slide 50. 
Other modifications of the invention will be apparent to those skilled in 
the art in light of the foregoing description. This description is 
intended to provide specific examples of individual embodiments which 
clearly disclose the present invention. Accordingly, the invention is not 
limited to these embodiments or to the use of elements having specific 
configurations and shapes and presented herein. All alternative 
modifications and variations of the present invention which follows in the 
spirit and broad scope of the appended claims are included.