Gear cutting – milling – or planing – Milling – Thread or helix generating
Reexamination Certificate
1999-09-01
2001-09-25
Wellington, A. L. (Department: 3722)
Gear cutting, milling, or planing
Milling
Thread or helix generating
C409S074000, C408S222000, C470S198000
Reexamination Certificate
active
06293740
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a threading tool for milling internal threads upon cavity walls of a workpiece to be threadingly secured with a male tubular fitting.
BACKGROUND ART
With the ongoing use of threaded fittings in industrial applications, internal and external threads are continuously formed to threadingly secure fittings. A number of tools are available for forming threads. For tubular fittings, a tool, such as tool
10
as depicted in
FIG. 1
, forms internal threads within walls of a cavity. Tool
10
is an elongated member having threads
12
formed thereon to cut or mill internal threads upon the walls (not shown) of a cavity. Thus, the internal threads may be formed and may extend along the walls of the cavity.
However, in the prior art, the axial depth along which the internal threads may extend is dependent upon the dimensions of the tool and the obstructions it may encounter. As shown in
FIG. 1
, tool
10
is an elongated member having a closed end
14
which enters the cavity to form internal threads upon walls of the cavity. The internal threads may extend as far as tool
10
can be inserted through the cavity. In many situations regarding tubular fittings, for example, in an anti-lock brake valve, the cavity of a female fitting has a floor around an axially disposed protuberance having a top extending upwardly from the floor, which interferes with the closed end of conventional tools.
In use, a male tubular fitting, which threadily inserts into the female tubular fitting, typically has an open end that receives the protuberance and engages with the cavity floor. When manufacturing the female fitting, the protuberance obstructs the closed end
14
of tool
10
and, in turn, limits the depth down to which internal threads may be formed and extend along the cavity walls. As a result, no internal threads may be formed past the top of the protuberance to the surface adjacent the cavity floor. Thus, a male tubular fitting is prevented from threadily attaching past the top of the protuberance of the female fitting. This tends to affect sealing integrity and allow unwanted leakage.
Although the existing cutting and milling tools may suffice in securing tubular fittings, the obstruction as described above creates an undesirable limitation which calls for an improvement to the existing tools. The absence of threads formed past the top of the protuberance to the internal surface adjacent floor of the cavity sacrifices strength in the attachment of the tubular fittings. That is, having internal threads formed past the top of the protuberance increases the strength in holding the tubular fittings together during normal environmental use, for example, in an antilock brake valve, in which the tubes engage a flared cone fitting.
Therefore, what is needed is a threading tool which forms internal threads upon cavity walls having a floor around an axially disposed protuberance having a top, wherein the internal threads extend along the walls past the top of the protuberance to the surface adjacent the floor.
DISCLOSURE OF INVENTION
Accordingly, it is an object of the present invention to provide an improved threading tool which increases strength in the attachment of tubular fittings. It is another object of the present invention to provide a threading tool which mills threads upon walls of a cavity having a floor around an axially disposed protuberance having a top extending upwardly, whereby the internal threads extend past the top to the surface adjacent the floor.
The present invention provides a threading tool comprising an elongated member which includes a threading portion. The threading portion has milling threads disposed thereon and an axial opening extending inwardly which defines a recess and a recess bottom. The threads extend an axial distance beyond the recess bottom.
The present invention also provides a method for milling an internal thread within a cavity of a workpiece. The method involves providing an elongated member having milling threads disposed at least partially adjacent an engaging end thereof. The elongated member, having an axis of rotation (F), may be secured to a mechanical driver. The method further includes providing a workpiece having a generally cylindrical cavity within the walls of which the thread is to be milled. The cavity has a longitudinal axis (A) and a floor around an axially disposed protuberance which has a top extending upwardly from the floor.
Then, the method further involves inserting the elongated member downwardly within the cavity parallel to the axis (A), displacing the member laterally within the cavity such that the milling threads engage the wall of the cavity while spinning the member around the axis of rotation (F), and moving the axis (F) within the cavity of the workpiece such that the axis (F) describes a circular orbital path within the cavity. The method further includes stopping the orbital movement of the member and displacing the member inwardly within the cavity away from the walls thereof.
In use, the tool mills internal threads upon walls of a cavity of a female tubular fitting to be threadily secured to a male tubular fitting. As the threading tool downwardly inserts in the cavity, the recess receives the protuberance while avoiding contact therewith, thereby allowing the tool to mill internal threads upon the internal surface of the cavity adjacent the floor thereof. Thus, the tool mills internal threads upon the cavity walls past the top of the protuberance.
These and other objects, features and advantages will be readily apparent upon consideration of the following detailed description in conjunction with the accompanying drawings.
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patent: 21960 (1858-11-01), Hickok
patent: 83371 (1868-10-01), Foster
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patent: 1281683 (1918-10-01), Spinney
patent: 1875362 (1932-09-01), Wells
patent: 2240840 (1941-05-01), Fischer
patent: 2335741 (1943-11-01), Contaldi
patent: 3774501 (1973-11-01), Brown et al.
patent: 4316683 (1982-02-01), Schott
patent: 4943191 (1990-07-01), Schmitt
patent: 5733078 (1998-03-01), Matsushita et al.
patent: 5873684 (1999-02-01), Flolo
patent: 5902079 (1999-05-01), Moore
Machinery's Handbook, 25th ed., New York, 1996, pp. 1852-1854.
Brooks & Kushman P.C.
Ergenbright Erica D.
Northern Tool Sales and Service Company
Wellington A. L.
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