Cutting by use of rotating axially moving tool – Tool or tool with support – With pitch-stabilizing ridge
Reexamination Certificate
1999-04-22
2001-03-27
Wellington, A. L. (Department: 3722)
Cutting by use of rotating axially moving tool
Tool or tool with support
With pitch-stabilizing ridge
C408S215000, C408S216000, C470S010000, C470S185000, C470S187000
Reexamination Certificate
active
06206620
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to a pivoting die for the cleaning, rethreading or chasing of threads on studs or bolts that have been damaged, rusted or inhibited with paint or other foreign matter build up.
2. Description of the Prior Art
A common method or technique currently in use for retreading or cleaning of studs, bolts is with the use of a hexagonal rethreading die. A common rethreading die has a defined entry leading into a central opening having threaded surfaces facing into the opening for thread forming or cutting. Strategically located around the opening are relief areas to permit cuttings or other foreign matter to fall away from the affected areas of the stud or bolt. A very common problem with this oft used rethreading die, is that of starting the die over damaged threads on the end of a stud or bolt. In most cases, damage to threads occurs at or near the unattached end of a stud making it difficult to engage a rethreading die with proper alignment to the thread pitch of the stud. This usually results in what is commonly called “cross threading”. On all-thread rods there are typically no open or free ends with which to attach a common rethreading die. In this situation a thread file is typically used. Depending on the amount of damaged or inhibited area this process could be very lengthy and laborious. Expensive or hard to find bolts create similar problems and are often just discarded. Hand reworking methods are often unsuccessful because of the critical nature of thread pitch and diameters. U.S. Pat. No. 4,572,032 issued to Kinzler Feb. 25, 1986 describes a conventional die modified to perform as a hinged rethreading die for primary use on in situ studs. However, this modification process is not simple nor is it effective. A conventional die is described as being sectioned into halves, with a machined slot at the top end to accept a multi-pin hinge device and an adjustment screw at the bottom end or closure point for fine adjustments. On few existing hexagonal rethreading dies, this process of modification can work in configuration only and seldom in function. Outer hexagonal wall thicknesses lessen with each increasing size in a conventional rethreading die set making it nearly impossible to accomplish this type of hinge modification. The overall manufacturing process associated with this die would be extremely costly making it relatively unaffordable. Also, with adjustments necessary for proper cutting of threads, using this type of a rethreading die in tight spaces becomes tedious. It is also noted that movement of the Kinzler die is in an outwardly fashion, which would necessitate reattaching or turning over of the die to make further passes over the damaged thread area.
U.S. Pat. No. 5,288,181 to Pinkston issued Feb. 22, 1994 describes a complicated and cumbersome tool for reconditioning and rethreading a stud made up of moveable jaws activated by a cam device. Provided this tool were to be effective, each partial rotation on a threaded stud would have to be accommodated by adjusting unspecified tension to a threaded collar above the moveable jaws creating imprecision and irregularity in the process.
U.S. Pat. No. 4,872,790 to Sibole issued Oct. 10, 1989 describes a rethreading die segmented into a plurality of sections held together by a tension spring. A segmented die is passed over a threaded member and re-engaged on the threads. An extremely difficult tool to use in tight areas requiring both hands to engage with risk of losing one or more segmented parts of the die with the dislodging of the tension spring. Proper meshing of the member threads and the die threads would be very difficult in areas of inhibited view.
U.S. Pat. No. 5,803,676 to Wienss issued Sep. 8, 1998 shows a single directional tapered and keyed device for drawing over damaged threads with the use of a driver. A complicated, inefficient method not allowing for bidirectional passage over inhibited threads or effective use in areas where clearance is of concern.
SUMMARY OF THE INVENTION
The present invention pertains to a pivoting split die for the cleaning, rethreading or chasing of threads on studs or bolts that have been damaged, rusted or inhibited with paint or other foreign matter build up. The present invention provides novel tooling for, and an improved method of rethreading, chasing and cleaning damaged or inhibited threads on studs or bolts and an improved method of manufacturing the rethreading die. The present invention is extremely simple to use. In situations where threads on a mounting stud or bolt have been damaged, cross-threaded, or inhibited with foreign matter, the present invention provides an easy alternative to standard rethreading or cutting dies. Apply an appropriate lubricant to the bolt or stud. Open up the pivoting die and locate around remaining good threads of bolt or stud. Secure the die with wrenching means and work back and forth over the inhibited threads until the die is completely free from the bolt or stud. The present invention has a nominal tolerance manufactured into the die so as to not require an adjustment in the closure gap of the die when applied to the stud or bolt. Since the present invention is not a new thread cutting device, typical cutting die or rethreading die adjustments are not necessary. The purpose of the present invention is to provide rejuvenation and cleaning of existing threads in order to accommodate a new nut or fastener to the stud or bolt or to aide in the removal of a nut or fastener by cleaning the threads. The present invention requires very little effort to operate effectively. Since no adjustment is necessary when using the present invention, very little time is needed to accomplish a rethreading or cleaning task. The present invention snaps closed around undamaged threads with fingertip pressure. Once closed and engaged with the threads of the stud or bolt any appropriate wrenching tool can be used effectively to perform the task. The present invention is bidirectional meaning there is no preferred position such as up or down.
The present invention is manufactured of simple methods. There is no requirement to modify existing conventional dies. This is costly and ineffective. The present invention requires only two opposing halves of identical configuration. When the two opposing halves are mated, a through hole is drilled for a pivot pin, a pivot pin is installed and thread surfaces and reliefs are formed with the two opposing halves closed. Forming the reliefs and thread surfaces with the two opposing halves in the closed position ensures the consistent placement and effectiveness of the rethreading surfaces once enmeshed with the threads of a stud or bolt. The thread surfaces and reliefs are formed of standard machining methods.
REFERENCES:
patent: Re. 23210 (1950-03-01), Johnson
patent: 888563 (1908-05-01), Wilkins
patent: 1465337 (1923-08-01), Binford
patent: 1488271 (1924-03-01), Miller
patent: 1803888 (1931-05-01), Basola et al.
patent: 2010913 (1935-08-01), Bruce et al.
patent: 2896495 (1959-07-01), Crawford
patent: 4572032 (1986-02-01), Kinzler
patent: 4872790 (1989-10-01), Sibole
patent: 5288181 (1994-02-01), Pinkston
patent: 5803676 (1998-09-01), Wienss
Carter Monica S.
Wellington A. L.
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