Valve seat refitting apparatus

A valve seat refitting apparatus. A cylindrical main body portion has a longitudinal bore which receives a centering guide. Longitudinal slots around the outer periphery of the main body portion receive cutting blades rigidly attached to cutting blade support. Radial and longitudinal positioning screws serve to position the supports and cutting blades to refit a variety of valve seats. Set screws lock the blade supports in the desired position. A bushing removably attached to the centering guide also allows the centering guide to be adapted to fit different size valve seats.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention is generally related to valve seat refitting tools and in 
particular to an apparatus used primarily to cut safety valve seats for 
reuse is high pressure vessels. 
2. General Background 
In high pressure situations safety valves open and close frequently. This 
results in foreign materials being trapped between the valve and valve 
seat which chip or dent the valve seat, causing leakage and eventual 
erosion. To maintain proper sealing, the valve seat must be recut to fit 
tightly with the valve. Apparatus known for cutting or refinishing nozzles 
and valve seats include the following. 
U.S. Pat. No. 4,090,805 issued to E. E. Grimsley entitled "Cutting Tool For 
Removing Governor Chest Nozzles And Refinishing The Nozzle Seats" 
discloses a portable cutting tool that rotates and axially advances two 
(2) symetrically positioned cutting blades that cut away weld material in 
annular overlapping paths. A second cutting head is provided for 
refinishing the nozzles seats after the nozzles have been removed. 
U.S. Pat. No. 2,393,361 issued to E. G. A. Flodman entitled "Pin Drill And 
End Mill" discloses symetrically positioned cutting blades. 
U.S. Pat. No. 4,178,115 issued to J. L. Pool, U.S. Pat. No. 4,626,143 
issued to D. C. Rembold, U.S. Pat. No. 3,901,619 issued to V. A. 
Scritchfield, U.S. Pat. No. 611,254 issued to A. R. Jackson, U.S. Pat. No. 
3,088,202 issued to R. J. Murray, U.S. Pat. No. 2,428,099 issued to L. A. 
Smith and U.S. Pat. No. 4,147,462 issued to J. R. Appleby, et al. teach 
valve seat refinishing tools and are representative of the state of the 
technology in this field. 
Although the present state of the art provides a variety of cutting tools, 
what is needed is a tool which is adjustable to fit a variety of sizes and 
capable of cutting three (3) faces of the valve seat at the same time. 
SUMMARY OF THE PRESENT INVENTION 
The present inventions solves the aforementioned problem in a 
straightforward manner. What is provided is a cylindrical body portion 
having longitudinal slots cut into four (4) tangential extremities on the 
body. Provided in each slot is a blade support for supporting a cutting 
blade. The blade supports are mounted in the longitudinal slots by allen 
screws. A bore provided in the body portion accepts a guide which fits 
into the valve seat to be refit. Rotation of the guide causes rotation of 
the cutting blades which refit the valve seat.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, it is seen that the invention is generally 
referred to by the numeral 10. Valve seat refitting apparatus 10 is 
generally comprised of main body portion 12, centering guide 14, means 16 
for adjusting centering guide 14 to fit different size valve seats, 
cutting blades 18, cutting blades support 20, and means 22 for adjusting 
the position of cutting blades 20. 
As seen in FIGS. 1-3, main body portion 12 is cylindrical and provided with 
four (4) longitudinal slots 24 substantially equally spaced around the 
outer periphery of body portion 12. Slots 24 extend from the forward end 
of body portion 12 toward the rear end and terminate before extending 
through the rear end. Body portion 12 is also provided with longitudinal 
bore 26 which is circular in cross-section and extends through the center 
of body portion 12. 
As best seen in FIGS. 1 and 2, bore 26 is adapted to receive centering 
guide 14. Centering guide 14 is adapted to be rigidly attached to body 
portion 12 by any suitable means such as tack welding or keyed slots such 
that rotation of centering guide 14 causes corresponding rotation of body 
portion 12. To this end, centering guide 14 is provided with a rear radial 
lateral bore 28 suitable for receiving a handle (not shown) for rotating 
centering guide 14 and main body portion 12. In operation, there is also 
provided a guide (not shown) above centering guide 14 to stabilize lower 
adjusting means 16, discussed hereafter. Centering guide 14 is provided 
with enlarged forward end 30. Adjacent its forward end, centering guide 14 
is provided with forward radial bore 32, best seen in FIG. 2, which 
provides an attachment point for means 16 for adjusting centering guide 14 
to fit different size valve seats. 
Adjusting means 16 is comprised of bushing 34 removably attached to 
centering guide 14 and which is formed form two halves 34a, 34b (in an 
alternate embodiment, ball bearings may be employed). Halves 34a, 34b are 
provided with countersunk bores 36a, 36b, respectively, to receive allen 
screw 38 and a nut (not shown) or half 34b may be threaded to receive 
screw 38. In this manner, bushing 34 may be attached to the forward end of 
centering guide 14 as seen in FIG. 1. Bushing 34 is sized so that it 
provided a relatively close fit within the interior bore of valve seat 40. 
This allows rotation of valve seat refitting apparatus 10 without any 
wobble for accurate cutting of the valve seat faces. Various size bushings 
may be used to adapted centering guide 14 to fit different size valve 
seats without the necessity of changing centering guide 14. 
As seen in phantom view in FIG. 4, cutting blades 18 are shaped to cut the 
three (3) necessary and separate surfaces of valve seat 40 all at the same 
time as apparatus 10 is rotated. These three (3) surfaces are forty-five 
(45.degree.) degree inside shoulder 42, raised horizontal annular surface 
or seat 44, and outer horizontal shoulder or relief 46. Cutting blades 18 
are rigidly attached to, or integral with in the preferred embodiment, 
cutting blade supports 20. Cutting blade supports 20 provide for 
adjustable positioning of blades 18 relative to body portion 12. Supports 
20 are sized to be received in longitudinal slots 24 and provided with 
threaded bores 48 which form part of means 22 for adjusting the position 
of cutting blades 18. 
Adjusting means 22 allows for radial and longitudinal adjustment of the 
position of cutting blades 18 so that a large variety of sizes of valve 
seats 40 may be refit with use of only one (1) apparatus 10. Means 22 is 
comprised of radial positioning screws 50, longitudinal positioning screws 
52, and set screws 54. As best seen in FIG. 3, radial positioning screws 
50 are threadably received in bores 48 of cutting blade supports 20 and 
are used to place supports 20 and consequently blades 18 at the desired 
radial position to fit the valve seat being refit. Longitudinal 
positioning screws 52 are used to set blades 18 at the desired depth for 
the valve seat being refit. Screws 52 are threadably received by threaded 
bores 56 at the rear end of body portion 12 such that they extend into 
slot 24 to abut against the rear end of cutting blade supports 20. Set 
screws 54 are threadably received by threaded bores 58 so as to extend 
into slot 24 and bear against supports 20 to lock blades 18 in the desired 
cutting position. 
As clearly seen in FIG. 2, each pair or set of set screws 54 is parallel to 
two pairs or sets of opposing radial positioning screws 50 (for example, 
set screws 54a are parallel to opposing radial positioning screws 50a, 50b 
and set screws 54d are parallel to opposing radial positioning screws 50c, 
50d), each pair of set screws 54 being offset from the radial line on 
which each parallel pair of radial positioning screws 50 project (set 
screws 54a offset from radial positioning screws 50a, 50b). Further, each 
pair or set of set screws 54 is perpendicular to the remaining two pairs 
or sets of opposing radial positioning screws 50 (for example, set screws 
54a are perpendicular to opposing radial positioning screws 50c, 50d and 
set screws 54d are perpendicular to opposing radial positioning screws 
50a, 50b). 
In operation, a bushing 34 is chosen according to a size which is capable 
of being rotated within valve seat 40 with a minimum of wobble. Bushing 34 
(or bearing) is then attached to centering guide 14. Centering guide 14 
and bushing 34 are then inserted into valve seat 40 and cutting blades 18 
are adjusted to properly mate with the valve seat faces to be refit and 
locked in position by set screws 54. With valve seat 40 rigidly held in 
place, a handle (not shown) is used to cause rotation of centering guide 
14 and consequently main body portion 12 and cutting blades 18 to refit 
all three (3) valve seat faces at the same time. The apparatus provides 
for economical use and a minimum of parts required as it is adjustable to 
fit a variety of valve seats and individual blades are easily replaced 
when worn or broken during use. 
Because many varying and different embodiments may be made within the scope 
of the inventive concept herein taught, and because many modifications may 
be made in the embodiments herein detailed in accordance with the 
descriptive requirement of the law, it is to be understood that the 
details herein are to be interpreted as illustrative and not in a limiting 
sense.