CA2194164A1

CA2194164A1 - Self-locking threaded connecting device

Info

Publication number: CA2194164A1
Application number: CA 2194164
Authority: CA
Inventors: Richard W. Vanderdrift
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-07-01
Filing date: 1995-05-05
Publication date: 1996-01-18
Also published as: TW268081B; EP0769108A4; AU2546295A; EP0769108A1; BR9508203A; AU689897B2; JPH10502435A; WO1996001379A1

Abstract

A self-locking threaded connecting device comprising a male component (11) with a recess locking thread type (31) and a female component (12) with a flexible thread segment (21). Tension from the alignment of the internal flexible thread segment urges projections (22) of the flexible thread segment into the recesses (32) of the recess locking thread and thereby prevent the threaded fastener from loosening and coming apart in response to axial pressure optionally combined with vibration, expansion, contraction or other movement. The projections (22) and recesses (32) are shaped so that the faces glide by each other and unlock with the application of adequate torque. The two threads are designed to work together. The female component (12) when used with a standard male component (11) without recesses (32) provides resistance to inadvertent loosing.

Description

~ W09610~379 r~".a~ -: 2~94164 Self-Lockin~ Threaded Connectin~ l)e.vicc F~An~rnnn~1 of thf~ TnvP.nti~n I . Field of the Invention The present invention relates to self-locking threads and threaded c~."..- ~;. ..~, and more particularly to seTf-locking threaded connection devices that may be discrete fasteners intended to secure two or more work pieces together and comprised of a comhinAtir n of a threaded bolt, cylinder, stud, shank or screw mated with a conlpl;.~ y threaded nut or hole, or that also may be an integral part of some other deviGe, such as the threads on the end of the arrn that screws into the threaded ...:... ,I,lin, ,1 A- y hole in the torso of a toy soldier.

~V0 96/01379 I _ 11 U., e. ~ --i2~ 94 ~ 64 2. I)~cnription of r h~ !lt~l Art Locking threaded fasteners and tbreaded çonnecting devices of a wide variety of types are available which reduce the tendency of male, generally cylindrical, threaded c. .."~ n. .a~ from altering their position in relation to their ~VII~IJVI~dillg female threaded ~omron~.nf, thereby reducing the tendency of such threaded fasteners and threaded connecting devices to loosen and come apart in response to vibration, expansion, contraction amd other movement. Many such fasteners function in this regard by increasing friction between the otherwise mated threads of the male and female çr.mr~ nte or between the fastener and the parts joined by the fastener. Examples include: loçk washers, tooth washers, blind thread bores filled with resilient inserts such as disclose.d in U.S. Pat.
No. 5,078,562 issued to DeMaitre on January 7, 1992, and screw thread profiles that jam or deform when tightened such as disclosed in U.S. Pat. No. 5,242,252 issued to Harle on September 7, 1993. Other such fasteners and cv ~ c function by increasing the friction between the engaging surfaces of the head of the male component and worl:. pieçe, or beh~een the female component and work piece such as disclosed in U.S. Pat. No.
4,290,4~9 issued to Nakae on September 22, 1981. In all such al~ , the increased friction makes rotation more difficult between the male and female ~,vll.lJon~ , thereb preventing inadvertent releare or loosening of the male and female r~f~mpnnente A
drawback of all these approaches is that the male and female ~ n. ~ can loosen at aoy axial pressure or tension less than that required to strip the male component out of the ~ WO96101379 r~ U.~ o20 9'4164 female component. Since the threads in each case fall away in the direction of a~ial pressure or tension, a portion of such pressure or tension is translated into a rotational force tending to loosen the r~ Also, fasteners using these approaches generally require high or increased torque to install, or mar the joint surface, or are not reusable, or require greater loads to be effective than is desirable to apply to some joints. Self-locking a~ such as cotter pins, lock wires, and nut assemblies comprising a first working nut and a second locking nut part as disclosed in U.S. Pat. No. ~,154,~60 issued to Copito on October 13, 1992, have the drawback of requiring additional installation effort.
Therefore, there is a need for threads, threaded fasteners, and threaded devices: (i) that will not come loose under loads equal or less than the fastener supports, (ii) that can be easily installed using cv~ iull~l tools, (iii) that employ torque values appreciably closer to those torque values only necessary to clamp together the wu~k,~ (as opposed to requiring higher torque values to provide increased resistance against loosening), and (iv) that can be installed as easily as standard fasteners. The present invention addresses these drawbacks in known prior threaded fasteners and threaded devices and meets these needs with a novel thread design which can be forged, rolled, stamped, or otherwise applied to threaded fasteners and threaded devices using c~ ..io.lol techniques. Improved threaded fasteners and threaded devices may therefore be lu~ uL~,lul~d at close to the cost of traditional locking threaded fasteners and devices.

Wo96/01379 r~l"J~, r-- ~

Brief D~c~ri,ption of the Drawin~e Figure lA is a side view of the invention in an assembled state.
Figure lB is a bottom view of the invention in an assembled state showing the flexible thread projections of the female component interacting with the thread recesses of the male ~
Figure 2A is a side view of adjacent thread rotations of the invention in an assembled state and showing one fiexible thread projection in an un ocked state as applied to maie and female fastening c.~
Figure 2B is a side view of adjacent rotations of the invention irL an assembled state increased in size to show detaiis of one flexible thread projection of the female component meshed with a recess of the ma'e component.
Figure 3A is a top view of the female fastening ~,UlLl~ 'Li flexible thread according to a preferred ~ ,l ,o~i; . ,1 of the present invention.
Figure 3B is a side view of the female fastening ~ JV..~ flexible thread according to a preferred . . . ,1"~ ,. . s of the present invention.
Figure 3 C is a bottom view of the femaie fastening component with its flexible thread according to a preferred ~ "l,o~ of the present invention.

~ W0 96101379 r~ r'~ -1 7 ~ 1 6~

Figuse 3D is a half cut away side view of tile female fastening component with its flexible thread according to a preferred -- S,o~l S of the present invention~
Figure 4A is a side view of adjacent rotations of an altemative r~ oll 11 of the invention in an assembled and unlocked state, where the recesses are located at the root of the recess locking thread, and extending into the core of the male fastening component between adjacent thread rotations of the male comrl-n~.nt and the projections ara located on the crest of the internal flexible thread segment.
Figure 4B is a side view of adjacent rotations of an alternative ~Illbod;..~ t of the present invention in an assembled and urlocked state as applied to male and female fastening .":.. "1 ,.,.... ,1 ~ where the projections of the flexible thread segment press axially against the recesses of the male thread. .
Reference ~ rnl~riqlc jn thP l::)rawin~pc 11-- male component 12 -- female component 21-- fernale ~U~ UII~ flexible thread segment 22 -- projections of the flexible thread segment 25 -- voids in flexible thread segment 26 -- poshioning tabs of the flexible thread segment 31 -- recess locking thread 32 -- recesses of the recess locking thread wo 96/0~379 "J4 1 l~4 Drt~ Description of the Preferred E."l~od;,...,.,l Figure I A shows a side view of a setf-locking threaded conn~rt;nn~ in an assembled state, comprising a male component (I l) having a first novelly formed thread (31) ~hereafter referred to as the "recess locking thread") and a female component (12) having applied to it a second novelly formed thread (31) (hereafter referred to as the "projection locking thread," more fuliy shown in Figure 2A). The projection locking thread is aligned on the female component so that its flexible projections (22) press up against the thread of the male component. The projection locking thread is either attached to the female component in a manner tbat enables its projections to rdex axially or radially, or the projections are formed in a manner that enables them to flex axially or radially. The female component is typically a threaded nut, bore, or hole. The male component is typically a threaded bolt, cylinder, stud, shank or screw. The projection locking thread and the recess locking thread are designed to work together so that, as the male component is being screwed into or out of the female component, the two threads engage each other in a slovel ma~mer (hereafter referred to as "meshing") and thereby lock~ In the drswings, dashed lines indicate that a feature appears only 1~ u~t~ ly from the given perspective.
Figllre lB shows an end view of the self-locking threaded connection of Figure lA
in a meshed state. Meshing occurs when any of the projections (22) of the fiexible thread segment (21) aiign with any of the recesses (32~ of the recess locking thread (31). When such alignment occurs, the tension pressing the female's internal flexible thread se~ment's ~ WO 96/0137~
5 ~ 1 6 ~

projections up against the male's thread (21) forces the aligned projection into the ~ UI ~ Ulldi;llg a.igned recess thereby meshing the threads. Once meshed, sufficient additiona'. higher torque in either the loosenhlg or tightening direction unmeshes the threads. The sides of the projections and recesses have a gentle enough slope so that torque can urge the projections to slide up and out of the recesses, and thereby unmesh the threads ~hen the torque is suf.~icient to overcome the friction between the faces of the engaged proiections and recesses and to overcome the tension pressing the fema.e's interna. flexible thread segment up against the recess loc.;ing thread (in addition to overcoming friction between the female's standard thread and the ma.e's thread as with standard thread cu..fl,~... dtiO.Is~, the threads unmesh and the fastener is in an un.ocked state until a pro~ection and a recess again a'.ign and mesh In Figures IA and IB, the flexible thread segment (21~ flexes p~,. ,U~ I;..uk.. ly to the axis of the fastener Figures 2A is a side view of one projection of the flexible thread segment in an un.ocked state In Figure 2B, the projection appearing in l igure 2A is shown in greater detail and is meshed with a recess of ~he recess locking th.ead. In the drawings, dashed lines indicate that a feature appears only intermittently from a given perspective.
Traditional threaded fasteners subjected to dynamic loads, stress reversals or vibration are susceptible to loosening Tightening such fasteners develops axial tensile stress that creates frictiona. resistance to loosening between mated threads and i~etween bolt and nut surfaces bearing against the joined materials This same tensile stress in the bolt also encourages the mating threads to slip due to the "downward" slope of their helix angle In W0 ~610i3 ,'9 4 1 ~1 4 the current invention, for the mating threads to slip even as vibration reduces resistance, the axial tensile stress must also lift or force the fle cible thread segment's projections out of the male thread's recesses and to overcome any remaining friction. To push or lift a projection out of a recers, the loosening torque resulting from tensile stress must be great enough to overcome the naturai spring retum action pushing the flexible thread seginent's projections into the male thread's projections. To ensure that the loosening torque is less than these resistive forces, the combination of the flexible thread segment's projection tension, the slope of the sides of the recesses, and the shape of the projections are in C~
engineered to create sufricient resistance to prevent inadvertently ioosening of the fastener.
In aiternative ~ . a ~, the faces of the recesses and projections can be formed so that the projections dig into the recesses when torque is spplied in either the tightening or loosering directions. In such ~ bod~ , the fasteners cannot be either further tightened or loosened once meshing occurs without damaging the projection or the recess.
When the female component is used with a traditional bolt or other male component without recesses, the fiexible thread segment presses up against the maies t'hread creating additional resistance to loosening. When the 'dexible thread is engineered to press with sufficient force against the thread of the male, the additional resistance prevents inadvertent loosening in the same manner as prevailing toroue nuts such as those with nylon inserts.
Figure 3A is a bottom view and Figure 3B is a side view of the female cu~ o~ .L'~
flexible thread segment (21 of Figure IB). In the preferred r~ lo.l;.~ .1, the female's flexible thread segment is not solid from its root to its crest for its full length A selies of voids in ~ WO96101379 ~ l q1~ r~

the filexible thread segment (2=t), formed extending from the thread crest toward the thread root, facilitate each projection (22) ;"~ ly meshing fuliy with any recess ~32 in Figure IB) when they aiign irrespective of the meshing state and position of the other projections and recesses. In the preferred rll.l,o.l;.,...a the individual projections align radialiy with the recesses, but the projections as a whole do not need to be arranged ~y~ liy with the recesses. In the preferred embodiment there are a prime number of recesses on e.ach thread rotation, seventeen, and six projections on the flexible thread segment. The fexible thread segment can be attached to the female component (12) in any manner so long as the flexible thread segment aiways rotates with the female component and cannot rotate ;".lrl,r.,fi.. ~l ly of the femaie comr~-n~nt In the preferred, r~ o~ ....t positioning tabs (26 of Figure 3A and 3C) prevent the flexible thread segment from rotating in relation to the rest ofthe femaie component (12) and position the flexible thread segment so that it's projections continue in the helix path formed by the standard thread of the thread of the female cnmr-~n~n~
Figure 4A is a side view of adjacent rotations of an aitemative ~ bo ihll~.lL of the invention in an assembled and unlocked state. The recesses (32) are located at the root and extend into the male CUIll~Joll~..lt ~ ~11) core between adjacent thread rotations of the recess locking thread (31).
Figure 4B is a side view of adjacent rotations of an aitemative t mho~iml~nt of the present invention in an assennbled and unlocked state where the projections of the internal wos6~ûl37s ,; ~:! r~ JJ..~ o2U
.~"1~

flexible thread segment press axially against the recesses of the male thread. In the ~.~,.l.o ~ shown, the }ecesses (32) and the project;ons are on the following flanks. In alternative ~IlLodi ~ they can be on the leading flanks.
While the present invention has been described with reference to certain preferred lbodil~ 4 those skilled in the art will recogniae that various l..odirl~L;~ may be provided. For example, there are many other embodiments ha~ing a variety of c~,lrl~ ~ dLi("ls for the shape, angle and si~e of the projections and recesses. The recesses can be located in the center of the thread flank instead of at or near the root. Instead of recesses on the e:~ternal thread, projections on the external thread can be used to mesh with the projections of the flexibls thread segment. The flexible thread segment can be more or less than one full rotation. These and other variations upon, and mr~tl;fi~ti~ns to, the preferred ~ "" .n are provided for by the present invention ~hich is only limited by the following claims..

Claims

Claims I Claim:

1. A threaded fastening device comprising:
a. a generally cylindrical first body having a longitudinal axis and an external helical thread having a root, b. a second body having an internal helical thread, a segment of the internal thread defined by at least one projection carried by a resilient arm mounted in the second body with the projection extending radially toward the axis of the first body when assembled such that when the first body and the second body are screwed together, the projection is urged radially toward the external thread, c. the external thread having a continuous root and a series of at least one means for meshing with the projection when the means for meshing and the projection axially and radially align, said at least one means for meshing each being confined between axially adjacent thread rotations of the external thread and contoured to permit the projection to move therepast in either direction of rotation without damage to either the at least one means for meshing or the projection.

2. The threaded fastening device of claim 1 wherein the means for meshing is a series of at least one projection between thread rotations.

3. A threaded fastening device as set forth in claim 1 wherein the at least one means for meshing comprises individual recesses formed in the root of the external thread, each individual recess being confined to a location between axially adjacent thread rotations without opening axially through an individual thread location.

4. A threaded fastener device as set forth in claim 1 wherein the said at least one projection is urged both radially and axially relative to the external thread.

5. A threaded fastening device as set forth in claim 1 wherein each said resilient arm extends in a direction generally parallel to the external thread.

6. A threaded fastening device as set forth in claim 5 wherein there are a plurality of said resilient arms each carrying a separate one of said at least one projection.

7. A threaded fastening device as set forth in claim 6 wherein said resilient arms all extend in the same direction.

8. A threaded fastening device as set forth in claim 6 wherein each said projection is located at an outer end of a resilient arm.

9. A threaded fastening device comprising:
a. a generally cylindrical first body having an external thread, b. a second body having an internal thread, a segment of the internal thread having at least one projection with spring return action and extending toward the axis of the first body when assembled such that when the first body and second body are screwed together, the projections are urged both radially toward the external thread's root and axially toward the external thread's flank by the spring return action, c. the external thread having a series of at least one means for meshing with the internal thread's projections when the means and projections axially and radially align and wherein the means for meshing are on the flank and root of the external thread.

10. A threaded fastening device as set forth in claim 9 wherein the at least one means for meshing comprises individual recesses formed in the root of the external thread, each individual recess being confined to a location between axially adjacent thread rotations without opening axially through an individual thread rotation.

11. A threaded fastening device as set forth in claim 9 wherein the projections are carried on resilient arms extending in a direction generally parallel to the external thread.

12. A threaded fastening device as set forth in claim 11 wherein each of said resilient arms carries a separate one of said at least one projection.

13. A threaded fastening device as set forth in claim 12 wherein said resilient arms all extend in the same direction.

14. A threaded fastening device as set forth in claim 9 wherein the means for meshing include recesses formed between adjacent thread rotations with each recess having a portion in the root and flank of the thread.