Bolt with extension to prevent thread misalignment

Details Bolt with extension to prevent thread misalignment Bolt with extension to prevent thread misalignment

2000-06-02

2001-10-02

Saether, Flemming (Department: 3627)

Expanded, threaded, driven, headed, tool-deformed, or locked-thr

Externally threaded fastener element, e.g., bolt, screw, etc.

Pilot end having means enhancing fastening or installation

C411S423000

Reexamination Certificate

active

06296432

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a bolt having a guide boss to prevent the oblique screwing in a female screw, more particularly, a bolt having an axle with thread and a guide boss formed at the end of said axle wherein said guide boss has a little smaller external diameter than an internal diameter of the female screw in which said bolt is screwed and a spiral guide groove is formed on said guide boss, said spiral guide groove connects to the root of said thread of said axle and has the same pitch as a pitch of said thread of said axle.
DESCRIPTION OF THE PRIOR ART
Hithereto, it has been known that the encroaching, the seizure, or the racing between a bolt and a nut is caused by an oblique screwing of the bolt in the nut. To prevent said oblique screwing, a bolt (
201
) having a guide boss as shown in
FIG. 3
has been provided. Said bolt (
201
) consists of a head (
202
), an axle (
203
) with a thread (
203
A) and a guide boss (
204
) formed at the end of said axle (
203
) and an external diameter Db of said guide boss (
204
) is set to be a little smaller than an internal diameter Dn of the nut (
205
) in which said bolt (
201
) is screwed.
When said bolt (
201
) is screwed in said nut (
205
), since said guide boss (
204
) having a little smaller external diameter Db than the internal diameter Dn of said nut (
205
) is first inserted in a female screw (
205
A) of said nut (
205
), the oblique screwing of said bolt (
201
) may be substantially amended.
Nevertheless, since a little play exists between said guide boss (
204
) of said bolt (
201
) and the inside (
205
C) of said nut (
205
), it is impossible to dissolve the oblique screwing completely and the problems of the encroaching, the seizure or the racing still remain.
OBJECT OF THE INVENTION
Accordingly, the object of the present invention is to provide a bolt having a guide boss which effectively prevents the encroaching, the seizure, or the racing by means of the oblique screwing.
SUMMARY OF THE INVENTION
Said object may be attained by a bolt having an axle with a thread and a guide boss formed at the end of said axle wherein said guide boss has a little smaller external diameter than a internal diameter of a female screw in which said bolt is screwed and a spiral guide groove is formed on said guide boss, and said spiral guide groove connects to a root of said thread of said axle, has the same pitch as a pitch of said thread of said axle and is deeper than said thread of said axle excepting both end parts of said spiral guide groove.
In said bolt (
101
) it is preferable that said thread has an incomplete thread from the front most end S to a fixed thread position, said incomplete thread the height of which is gradually increasing from O to the height of said complete thread has a range of an angle on the circumference of said axle between 50° and 100°.
Further it is preferable that said spiral guide groove is set to be deeper than said thread of said axle excepting both end parts of said spiral guide groove and at the rear most end connecting to a root of said thread of said axle, said spiral guide groove is set to be gradually shallower toward said axle so that the root of said spiral guide groove is situated at the same level as the root of said thread of said axle.
And further, it is preferable that the depth of said spiral guide groove excepting both end parts of said spiral guide groove is set to be between 10 and 70% of the depth of the thread of the female screw.
When said bolt (
101
) is screwed in the female screw (
105
A) of a nut (
105
), even if said bolt (
101
) is obliquely screwed in said female screw (
105
A) of said nut (
105
), since said spiral guide groove (
104
A) is formed on the circumference of said guide boss (
104
) of said bolt (
101
), during screwing said bolt (
101
) in said female screw (
105
A) of said nut (
105
), the thread of said nut (
105
) engaging with the spiral guide groove (
104
A) of said guide boss (
104
) progresses toward the thread of said bolt (
101
) guided by said spiral guide groove (
104
A).
When the front most end of the thread (
105
B) of said nut (
105
) reaches the rear most end E of the spiral guide groove (
104
A) of said boss (
104
) and the thread (
105
B) of said nut (
105
) is then engaging with the thread (
103
A) of said axle (
103
) of said bolt (
101
) to amend the oblique screwing of said bolt (
101
). Thus the oblique screwing of said bolt (
101
) is amended and said bolt (
101
)is further screwed in said nut (
105
) and the thread (
105
B) of said nut (
105
) is introduced in the thread (
103
A) of said bolt (
101
) by rotating propulsion of said bolt (
101
) from the spiral guide groove (
104
A) of said guide boss (
104
) to engage together.
As above described, the oblique screwing of said bolt (
101
) to the female screw (
105
A) of said nut (
105
) is amended to prevent effectively the encroaching, the seizure, or the racing between said bolt (
101
) and said nut (
105
).


REFERENCES:
patent: 2021704 (1935-11-01), Thatcher
patent: 2113600 (1938-08-01), Olson
patent: 3527136 (1970-09-01), Wilson
patent: 3878759 (1975-04-01), Carlson
patent: 5234301 (1993-08-01), Grossberndt
patent: 6089806 (2000-07-01), Reynolds

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