FIELD OF THE INVENTION

This invention relates to self locking and tamper-resistance or tamper-proof fasteners, and to release tools operable to release unlockable embodiments thereof.

BACKGROUND OF THE INVENTION

It is known in the prior art to use a self-locking nut to cooperate with a mating bolt to create a tamper-proof or tamper-resistant fastener by preventing or resisting relative rotation between the nut and bolt in a direction that would otherwise unthread the nut from the shaft of the bolt.

U.S. Patent No. 2,306,806 discloses the use of a spring helix and pitch mismatch between a nut and mating bolt to create an axial thread pressure that imposes a frictional resistance to the said nut equivalent when both winding or unwinding the nut in respect to the mating bolt - thus diminishing the possibility of loosening of the nut by vibration or shock.

U.S. Patent No. 2,391 ,513 teaches a lock nut having a spring helix of opposite hand to the thread and diameter mismatch between the nut and a mating bolt to create a perimeter thread pressure that imposes a helical lock when attempting to unwind the nut from the bolt.

Other examples of self-locking nuts are disclosed in U.S. Patent Numbers 3,272,250 and 3,417,801 ,

Applicant has developed self-locking threaded fastener components presenting features and advantages not seen in the prior art.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a self-locking threaded fastener component for mating with a second threaded fastener component in a locking manner, the self-locking fastener component comprising: a body having first and second opposing ends spaced apart along a longitudinal axis and comprising an open helical portion coiling around and along said longitudinal axis between the ends of the body; and threading formed on the body about the longitudinal axis over a length spanning therealong and including at least part of the helical portion of the body; wherein the body is configured at the first end for compatibility with a tool of predetermined size and shape, and configured at the second end for incompatibility with the same tool of predetermined size and shape; and wherein the threading include threads at the helical portion of the body that are mismatched in pitch or diameter relative to the second threaded fastener component to provide a frictionally tightening action of the helical portion of the body when mated with the second threaded fastener component.

The body may have a first cross-sectional size and shape compatible with the tool at the first end and a second cross-sectional size and shape incompatible with the tool at the second end.

The second cross-sectional size and shape may differ from the first cross- sectional size and shape in one or both of size and shape.

Preferably the first cross-sectional size and shape is hexagonal. The second cross-sectional size and shape may be non-hexagonal, may be free of any flat sides, may comprise only curved sides, and may be round.

In another embodiment the second cross-sectional size and shape may comprise at least one pair of opposing flat sides, may comprise only flat sides, and may be configured for compatibility with a second tool of different predetermined size and shape. The second cross-sectional size and shape may differ from the first cross-sectional size and shape only in size, for example with the cross-sectional size and shape at each end of the body being hexagonal.

The threading may be internally formed on the body to define a female self- locking fastener component, in which case the threads at the helical portion preferably have a smaller diameter than found at other portions of the threading between the helical portion and the first end of the body.

Alternatively, the threading is externally formed on the body to define a male self-locking fastener component, in which case the threads at the helical portion preferably have a larger diameter than found at other portions of the threading between the helical portion and the first end of the body.

In the male fastener component, the second end of the body may comprise a hollow portion at which an interior of the body is engagabie by a second tool of different predetermined size and shape. In this instance, the hollow portion of the second of the body may be hexagonal in cross-section.

The threads and the helical portion may extend in opposite hand directions around and along the longitudinal axis.

According to a second aspect of the invention, there is provided a release tool for disengagement of a self locking fastener employing a fastener component having distinctly configured first and second end portions respectively operable for unlocking and loosening said fastener, the release tool comprising: a first fastener engaging portion shaped to rotationally engage with said first end portion of said fastener component; and a second fastener engaging portion coupled to the first fastener engaging portion and shaped to rotationally engage with said second end portion of said fastener component; wherein the first fastener engaging portion is sized and shaped to provide an amount of rotational play about the first end portion of the fastener to allow rotation of the first fastener engaging portion about the first end portion of the fastener by the offset angle, while the second fastener engaging is rotationally engaged with the second end portion of the fastener, before rotationally engaging the first end portion of the fastener. The first and second fastener engaging portions may be female and male features respectively, the female feature of the release tool arranged to engage over a head of a bolt-type fastener component and with the male feature projecting through a bore of the bolt-type fastener component to reach the second end portion thereof from the head of the fastener component. In such instance, at least part of the male feature of the release tool preferably has a cross-section with straight sides for rotational engagement of an at least partially straight-sided cross section of the bore of the fastener at the second end portion.

Alternatively, the first and second fastener engaging portions may both be female features for engaging over a pair of male features arranged to engage over male features axially spaced along the fastener component.

The second fastener engaging portion may be hexagonal in shape.

The first fastener engaging portion may feature trapezoidal boundary segments in cross section for initially receiving corners of the first end portion of the fastener component at intermediate positions within said trapezoidal boundary segments before relative rotation between the first fastener engaging portion of the release tool and the first end portion of the fastener brings sides of the first end portion of the fastener into contact against end walls of the trapezoidal boundary segments of the release tool.

According to a third aspect of the invention there is provided a self-locking fastener component in combination with a release tool for disengagement of same, the fastener component having distinctly configured first and second end portions respectively operable for unlocking and loosening said fastener, and the release tool comprising a first fastener engaging portion shaped to rotationally engage with said first end portion of said fastener component and a second fastener engaging portion coupled to the first fastener engaging portion and shaped to rotationally engage with said second end portion of said fastener component; wherein an offset angle is provided either between the first and second fastener engaging portions of the release tool about an axis of said release tool, or between the first and second end portions of the fastener component about an axis of said fastener component.

According to a fourth aspect of the invention there is provided method of manufacturing a self locking threaded fastener component comprising: providing a threaded fastener component comprising a body having first and second opposing ends spaced apart along a longitudinal axis and threads formed on the body about the longitudinal axis over a length spanning therealong; with the threaded fastener component mounted on a workpiece support, creating an open helical portion of the body between the opposing ends thereof by forming a helical cut in the body over at least a partial length of the body, including at least a portion thereof occupied by the threads, by effecting relative movement along and around the longitudinal axis between the threaded fastener component and a cutting device. The method preferably comprises rotating one of the threaded fastener component or the cutting device about the longitudinal axis.

The method may comprse displacing the other of the threaded fastener or the cutting device along the longitudinal axis.

The method may comprise rotating the threaded fastener component about the longitudinal axis, and holding the cutting device in a rotationally fixed position.

Preferably the cutting device comprises a laser cutter.

The method may comprise moving the laser cutter toward and away from the longitudinal axis during rotation of the threaded fastener component to maintain a consistent radial depth to which the laser cutter penetrates the threaded fastener component relative to the longitudinal axis.

The step of forming the helical cut comprises may comprise cutting partially through the body from an outer periphery thereof to a hollow interior thereof.

With the threads of the fastener component running in a first hand direction about the longitudinal axis, the step of creating the open helical portion of the body may include forming the helical cut in an opposite second hand direction about the longitudinal axis.

According to a fifth aspect of the invention there is provided machine for manufacturing a self locking threaded fastener component comprising: a workpiece support arranged to carry a threaded fastener component thereon; a cutting device operable to cut the threaded fastener component; and a cutting control system arranged to effect relative movement between the workpiece support and the cutting device both around and along a longitudinal axis of the threaded fastener component to form a helical cut in the threaded fastener component.

There may be provided a rotational drive mechanism coupled to the workpiece support for rotation thereof about the longitudinal axis.

There may be provided a linear displacement mechanism coupled to the cutting device to effect movement thereof along the longitudinal axis.

There may be provided a second linear displacement mechanism coupled to the cutting device to effect movement thereof toward and away from the longitudinal axis to control a cutting depth thereof.

The cutting control system preferably comprises a numeric control system.

There may be provided a coolant conduit associated with the workpiece support and operable to direct a cooling fluid thereto during cutting of the threaded fastener component by the cutting device.

The workpiece support may comprise a rotatable spindle, with the cooling conduit comprising an internal passage extending axially along the spindle.

According to a sixth aspect of the invention there is provided a self-locking threaded fastener component for mating with a second threaded fastener component in a locking manner, the self-locking fastener component comprising: a body having first and second opposing ends spaced apart along a longitudinal axis and comprising an open helical portion coiling around and along said longitudinal axis between the ends of the body; and threading formed on the body about the longitudinal axis over a length spanning therealong and including the entire helical portion of the body; wherein over the entire helical portion of the body, the threading is mismatched in pitch or diameter relative to the second threaded fastener component to provide a frictionally tightening action of the helical portion of the body when mated with the second threaded fastener component.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which illustrate exemplary embodiments of the present invention:

Figure 1 is a side elevation view of a first embodiment tamper proof lock nut formed in accordance with the present invention;

Figure 2 is an end elevation view taken from the right of Figure 1 ;

Figure 3 is an axial sectional view (A-A) of the nut of Figures 1 and 2;

Figure 4 is an isometric view of the nut of Figures 1 and 2;

Figure 5 is an axial sectional view (A-A) of the nut of Figures 1 and 2 in the condition when threaded onto a bolt;

Figure 6 is a side elevation view of a second embodiment locking nut formed in accordance with the present invention, and including a mechanism to release the helical lock;

Figure 7 is an end elevation view taken from the right of Figure 6;

Figure 8 is an axial sectional view of the nut of Figure 6 and 7;

Figure 9 is an isometric view of the nut of Figures 6 and 7;

Figure 10 is a perspective view of a third embodiment locking bolt formed in accordance with the present invention, and including a mechanism to release the helical lock from either end of the bolt;

Figure 11 is a side elevational view of the locking bolt of Figure 10;

Figure 12 is an end elevational view taken from the left of Figure 11 ;

Figure 13 is an axial sectional view (A-A) of the nut of Figure 12;

Figure 14 is a perspective view of a fourth embodiment locking bolt formed in accordance with the present invention, and including a mechanism to release the helical lock from only one end of the bolt;

Figure 15 is a side elevational view of the locking bolt of Figure 14;

Figure 16 is an end elevational view taken from the left of Figure 15;

Figure 17 is an axial sectional view (A-A) of the nut of Figure 16;

Figure 18 is a perspective view of a fifth embodiment unlocking tool in accordance with the present invention for releasing the helical lock of the bolt of Figure 10;

Figure 19 is a side elevational view of the unlocking tool of Figure 18;

Figure 20 is an end elevational view taken from the right of Figure 19;

Figure 21 is an axial sectional view (A-A) of the unlocking tool of Figure 20; Figure 22 is a perspective view of the unlocking tool of Figure 18 engaged with the locking bolt of Figure 10 in an unlocking condition acting to disengage the helical lock of the bolt.

Figure 23 is an end elevational view of the unlocking tool and bolt of Figure

22;

Figure 24 is an axial sectional view (E-E) of the unlocking tool of Figure 23;

Figure 25 is an end elevational view of the unlocking tool and bolt of Figure 22, but with the helical lock of the bolt engaged before disengagement thereof through rotation of the unlocking tool;

Figure 26 is a perspective view of a sixth embodiment unlocking tool in accordance with the present invention for releasing the helical lock of the nut of Figure 6;

Figure 27 is an end elevational view of the tool of Figure 26 while engaged on the nut, as viewed from a driven end thereof;

Figure 28 is a side elevational view of the unlocking tool of Figure 26 while engaged on the nut prior to disengagement of the helical lock thereof;

Figure 29 is an axial sectional view (F-F) of the unlocking tool and nut of

Figure 28;

Figure 30 is an end elevational view of the unlocking tool and nut of Figure 28, from opposite the end view of Figure 27;

Figure 31 is an end elevational view of the unlocking tool and nut of Figure 28 with the tool in an unlocking condition acting to disengage the helical lock of the bolt.

Figure 32 is an axial sectional view (G-G) of the unlocking tool and nut of

Figure 30;

Figure 33 is a perspective view of a CNC machine for manufacturing a self locking fastener component of the present invention.

DETAILED DESCRIPTION

Fasteners

A first embodiment self-locking nut 10, as shown in Figures 1 to 5 inclusive, comprises a conventional solid nut portion 12 spanning an axial length z from a first end 14 of the nut 10 and a spring helix portion 16 spanning a second axial length y from the solid nut portion 12 to the opposing second end 18 of the nut 10. It will appreciated that by 'solid' nature of the solid nut portion is referring to the uninterrupted or continuous nature of the nut's annular body both axially along and circumferentialiy around the longitudinal axis of the nut at this 'solid' portion. The internal bore of the solid nut portion 12 is threaded for cooperation with a complementary external thread formed on a bolt 20 (Figure 5). The outer periphery of the sold nut portion 12 is desirably shaped to polygonal form, such as the hexagonal form of figure 1 and 2, so as to cooperate with a conventional wrench, socket or similar tool.

The tamper proof nut 10 incorporates a spring helix portion 16 whose hand rotational direction coils around the longitudinal axis of the nut in opposition to the hand rotation direction of the thread helix, which runs the full length of the nut 10 from one end 14 to the other 18.

In the preferred nut embodiment, when not applied to a bolt and without application of other forces, the convolutions of the spring helix take up a position at rest with a reduced inner diameter when compared to the remaining inner radius of the threads of the nut. The elasticity of the spring helix provides for thread inter-engagement between the nut and bolt and creates a pressure acting around the circumference of the threads throughout the plurality of turns of the spring helix 16.

When the nut 10 is threaded on a bolt 20 via the larger diameter threading at the first end 14 of the nut at the solid portion 12, the bolt thread serves to expand the diameter of the nut's spring helix convolutions upon reaching the smaller-threaded helical portion 16 under continued relative rotation between the nut and bolt in the same direction. In resisting this expansion, the nut's spring helix 16 exhibits a perpendicularly pressure on the circumference of the bolt.

This nut may readily and effectively be tightened toward the head 22 of the bolt 20, as with a conventional wrench, and retains its grip notwithstanding severe and prolonged vibration. Any attempt to remove the nut through axial counter rotation applied to the nut faces (i.e. through rotation in the opposite direction that would loosen a conventional non-locking nut away from the bolt head), for example with a conventional wrench, provokes the helix to bind onto the bolt and thus lock the nut. That is, the tight frictional fit between the bolt and the nut at the reduced-diameter helical portion 16 of the nut provides a resistance to the rotation of the nut body in the direction that would be expected to loosen the solid nut portion 12, and this resistance effectively fixes the reduced-diameter helical portion 16 in a stationary position on the bolt. With the reduced-diameter helical portion 16 thus held against rotation, the attempt to rotate the solid nut portion 12 in the desired loosening direction is working to radially tighten the helical portion since the reduced-diameter helical portion is held stationary by its tight fit on the bolt. This tightening of the helical portion thus increases the circumferential pressure exerted on the bolt by the nut, thereby locking the nut against attempted removal. The solid nut portion may be of same length to a comparable standard nut and so exhibit the same tensile and shear properties as a standard nut.

In the first embodiment of Figures 1 through 5, the cross-sectional shape of the helical portion 16 in planes perpendicular to the longitudinal axis of the nut is circular, so that the curved surfaces of the round periphery are not engagable by a conventional wrench or socket. That is, the round shape is not easily engagable by conventional tools in a manner providing sufficient gripping force to rotate the nut. That is the round end of the nut is rendered effectively incapable of transmitting a rotational torque. The round shape is unengagable by the straight or serrated sides of a conventional socket or non-adjustable wrench of fixed or static size and shape, especially within the confines of non-destructive use of a tool using an easily attainable amount of force in a discrete and inconspicuous manner, and the material employed to make the fastener is selected to be of sufficient hardness so as to be effectively undeformable into a grippable shape by the straight or serrated sides of an adjustable wrench, pliers, pipe wrench, or other conventional handheld or portable tool. The locking action thus removes the possibility of inadvertent loosening of the nut by vibration or shock, and stops the removal of the nut using conventional means. The outer diameter of the helical portion 16, at all positions along the longitudinal axis it coils around, does not exceed the diameter of the hexagonal cross-section of the solid nut portion 12 (i.e. does not exceed the diameter of an imaginary circle inscribed within the hexagonal cross-section of the solid nut portion). Accordingly, a conventional wrench or socket can be slid axially over the smaller-diameter helical portion 16 into engagement with the larger- diameter hexagonal nut portion to drive rotation of the nut in the tightening direction displacing it toward the head 22 of the bolt 20.

The nut can optionally incorporate a mechanism to defeat the helical lock and thereby permit removal, as demonstrated by the second embodiment nut 10' shown in Figures 6-9. Like that of the first embodiment, the nut 10' features a threaded internal through-bore extending through its body along a longitudinal axis from one end 14 of the nut 10' to the opposing other end 18'. Again, a solid hexagonal portion 12 of larger diameter than a remainder of the nut is defined adjacent the first end 14 of the nut, while an open helical portion 16' extends from the opposing end of the larger solid portion 12 toward the second end 18' of the nut 10'. Again, the helical portion 16' coils around the helical axis in a hand direction opposite that of the internal thread of the nut 10', and the thread diameter reduces moving from the larger solid portion 12 to the open helical portion 16.

Where the second embodiment differs, is in the presence of a second hexagonal portion 30 at the end of the helical portion 16 opposite the first hexagonal portion 12. That is, while the helical portion 16' again has cross-section of circular outer periphery over most of its axial length, the cross-section of the nut 10' is hexagonal over an axial distance approaching the second end 18' of the nut. The second hexagonal portion 30 has an outer diameter less than that of the first hexagonal portion 12

Accordingly, a conventional wrench or socket can slide axially over the smaller-diameter hexagonal end portion 30 and the intermediate helical portion 16 into engagement with the larger-diameter hexagonal end portion 12 to drive rotation of the nut in the tightening direction displacing it toward the head 22 of the bolt 20.

When seeking to remove the second embodiment nut 10', application of an axial counter-rotation on the smaller hexagonal end portion 30 of the nut 10' releases pressure on the circumference of the inter engaging threads - thus releasing the helical lock and so permitting and unwinding the nut. That is, rotating the smaller hexagonal nut portion 30 in the direction opposite to the direction in which the nut was originally rotated onto the bolt radially expands the helical portion to release the locking pressure thereof against the circumference of the bolt. This release of the locking pressure allows the nut to be removed and replaced many times without developing excessive wear either on its own threads or on those of the bolt.

Having the lock-releasing, tool-engagable second end 18' smaller than the nut-tigtening, tool-engagable first end 4 not only makes it easier to slide an appropriately sized tool over the second end to the first end, but also aids in visually distinguishing the tightening and lock-releasing functionality of the opposing ends to the user to ensure that the nut is oriented properly to thread it onto the bolt or other threaded male member at the correct end of the nut.

The unlocking functionality of the second embodiment can be designed to be compatible with conventional tools, for example by employing the illustrated configuration of a hexagon unlocking end 30 for cooperation with a standard conventional wrench, or to require use of a specific purpose-designed tool to better prevent unlocking by unauthorized personnel.

A mating thread of either hand may be used between the nut and mating bolt, the desirable pressure around the circumference on the inter-engaging threads of the nut and bolt being provided regardless. The helical spring portion of the nut may be of reverse hand and normal hand. The hand of helix spring in contrast to the hand of thread determines which end of the nut will have lock and which will have unlock capabilities. That is, while the preferred embodiment for general application features a helical cut in the opposite hand to the thread so that the nut threads in the advancing direction through rotation of the leading or front end and threads in the retreating direction through rotation of the trailing or rear end, it is possible to make a nut that operates the other way, i.e. that is advanced or done-up from the rear end and retreated/withdrawn/undone from the front end by using a helical cut of the same hand direction to the thread.

Thread pitch mismatch and resulting axial pressure may also be incorporated into the said nut design where it is desirable to do so, for example in place of a thread- diameter mismatch to provide a similar frictional engagement action at the helical portion. The helical spring can be of variable pitch and width. It may also be of a form that includes multiple helical springs. Whilst the solid hexagonal head and reduced removal head size is the preferred embodiment it can be seen that the nut head or heads of the first two embodiments can be of any form capable of transmitting a rotational torque, can be of any size in relation to the spring helix, and can be solid or split by a helical or other cut. In the illustrated embodiments of the nut, the helical portion has a smaller outer diameter than the wrench-engagable hexagonal portions, but other embodiments may feature a helical portion that exceeds at least one of the one or two wrench engagable portions. While the illustrated embodiments of the nut feature differently configured ends so that a tool engagable to the nut at one end is incompatible with the other end, other embodiments may feature two equally sized hexagonal ends engagable by the same tool, while still presenting advantage over prior art fasteners lacking the effective locking action provided by tight frictional engagement over the full length of the helical portion by the thread mismatch provided over the entire helical portion relative to the bolt on which the nut is to be engaged.

The cross section of the helical portion, the frictional mismatch, the pitch of the helix and the material characteristics are all variables that can be configure to adjust the fasteners locking characteristics. For example a small diameter mismatch and small helical portion cross section of relatively weak material will result in a fastener than can be done up very easily (for example, manually using ones fingers instead of needing a wrench or socket) and will still lock. However it's resistance to vibration and some shocks will be lower and its sensitivity to surface contamination will be higher, for example possibly losing lock functionality if coated with oil or other lubricant. These characteristics can thus be customized to suit particular fastener requirements.

While the first two embodiments show nuts (internally threaded female fastener components), the third and fourth embodiments shown in Figures 10 through 14 demonstrate that the helical spring lock principle described herein can also be applied to externally threaded male fastener components.

Figures 10 to 13 show one embodiment of a self locking bolt 40. In a conventional manner, the bolt 40 features a head 42 of hexagonal cross-section, and an externally threaded shaft 44 projecting axially to one side of the head 40. The bolt 40 departs from a conventional design in the presence of an axial through-bore 46 extending centrally through the head and shaft from one end of the bolt to the other, and the presence of helical cuts 48 extending through the shaft wall over a partial length thereof near the free end 50 thereof opposite the head 42. Like in the nuts of the preceding embodiments, the helical cuts, and thus the resulting helical portion 52 of the fastener component 40, extend around and along the longitudinal axis of the fastener component in a rotational hand direction opposite the threading.

The locking bolt 40 has a helical locking effect that takes place under threaded engagement with the threaded bore of a conventional nut or other internally threaded female fastener component, much like the locking effect of the locking nuts described above when engaged with the threaded shaft of a conventional bolt, threaded rod or other externally threaded male fastener component.

A nut is engaged onto the threaded shaft 44 over the free end 50 thereof, as is done for a conventional bolt. Upon sufficient threading of the nut toward the head 42 of the bolt 40, a portion of the nut's internal threading will be engaged in the thread turns at the helical portion 52 of the bolt. As with a conventional bolt, driven rotation of the bolt head 42 in a predetermined direction (e.g. clockwise as viewed from the head-equipped end of the bolt for conventional right-hand threading) relative to the nut will further this advance or tightening of the nut toward the head of the bolt. With a tight fit of the threads near the free end of the bolt 50 with respective threads on the nut, rotation of the bolt head 42 relative to the nut in an opposite direction associated with loosening of a conventional nut-bolt fastener, will rotate the end of the helical portion 52 nearest the head 42 relative to the other end of the helical portion 52 nearest the free end of the shaft due to the frictionally tight engagement of the nut and bolt over the helical portion. The relative rotation between opposing ends of the helical portion causes a radial expansion that forces the bolt threads on the helical portion further outward into tighter frictional engagement with the internal threads of the nut. That is, the helical portion of the bolt binds outwardly against the nut, exerting circumferential pressure between the bolt and nut at the bolt's helical portion to create a locking effect.

To allow release of this locking effect for disengagement of the nut from the bolt, the axial through bore 46 of the bolt 40 features a hexagonal cross-section 54 at the free end of the bolt shaft 44. A hex key, Allen wrench, or similar tool of hexagonal section can thus rotationally engage this hexagonally shaped hollow interior at the free end of the bolt to unlock the binding helical action between the bolt and the nut engaged thereon. A hexagonal tool can project into this hexagonal unlocking feature 54 of the bolt 40 from the free end 50 of the bolt 40, or if sufficient in length, via the internal bore 46 from the head 42 of the bolt. The hexagonal tool is rotated in the loosening direction of the thread (i.e. counterclockwise as viewed from the head end for right-handed threading), which acts to reduce the diameter thereof and release the outward locking pressure of the helical portion of the bolt against the interior of the surrounding nut.

Figures 14 to 17 show an alternate locking bolt 40' that is similar to the locking bolt 40 of Figures 10 to 14, but is only unlockable from one end thereof. Instead of a full through-bore, the bolt 40' features a blind hole 46' extending thereinto, but not fully therethrough, on the central longitudinal axis of the bolt shaft 44' from the free end 50 thereof. Accordingly, in this embodiment, the hexagonally keyed unlocking feature 54 of the bolt 40' is only accessible from the free end 50 thereof, and not from the head end 42' of the bolt 40'.

The helical cuts 48 of the bolt 40' cut into the blind hole 46', which defines the open or hollow interior space around which the helical portion coils or wraps. The single- ended unlockability of this embodiment is useful for applications requiring a higher level of security than the double-ended unlockability of the embodiment of Figures 10 to 13. Another embodiment may omit unlocking features altogether, for example having a blind-hole 46' like that of Figure 17 to define the open interior of the helical portion of the bolt shaft, but having a uniform circular cross-section over the full length of the blind hole, without any hexagonal, straight sided, or otherwise keyed end portion for engagement by an unlocking tool.

The locking bolt's helical spring can be of variable pitch and width. It may also be of a form that includes multiple helical springs. In a manner similar to how the locking nut described above uses a normally reduced thread diameter at the helical portion to create a circumferential pressure contributing to the lock functionality of the fastener, the bolt maybe configured to present a larger thread diameter at the helical portion when in its normal relaxed state prior to engagement with a nut, thus providing a similar circumferential pressure between the nut and bolt to contribute to the locked-together. Also, whilst the solid hexagonal head of the bolt and hexagonal "alien key" of the opposing end is the preferred embodiment of the locking bolt, it can be seen that the engagement mechanisms at either ends of the bolt can be of any form capable of transmitting a rotational torque, can be of any size, and can be solid or split by a helical or other cut.

The above embodiments provide self locking and tamper proof fastener components of economical construction, adapted for the engagement with a plurality of threads on a mating component and arranged to resiliently exert a pressure on the circumference of the engaging threads, whereby any attempt to loosen the component invokes a helical lock mechanism such that vibration, shocks, other mechanical forces cannot loosen the fastener.

Some embodiments further prevent disengagement by counter rotation using a conventional wrench. Other embodiments provide an optional mechanism to loosen the nut using conventional or unconventional tools to circumvent the above described helical lock. It is a feature of the helical lock that the higher the torque applied in an attempt to loosen the fastener component, the higher the pressure that is exerted on the engaging screw threads and the tighter the fastener is bound. Further, the invention provides fastener components of this character having minimum size and weight to achieve the above described characteristics.

Unlocking Tools

Figures 18 to 25 illustrate an unlocking tool 60 for cooperation with the locking bolt 40 of Figures 10 to 13. The tool 60 has a general structure resembling that of a socket for a conventional socket wrench, but with the addition of a hexagonal shaft 62 projecting axially from the socket opening. The socket body 64 features a cylindrically shaped driver engagement portion 66 having a rectangular recess 68 extending thereinto from an end face 68 thereof. Carried at the opposing end of the driver engagement portion 66 is a socket defining portion 70 with a cylindrical outer periphery and a segmented interior periphery defining a socket 72. A solid portion of the socket body defined between the rectangular recess 68 and the socket 72 forms closed ends or bottoms 68a, 72a thereof. The hexagonal shaft 62 lies on the central longitudinal axis of the socket 72 and projects from the closed end 72a of the socket 72 past the opposing open end thereof.

The length of the hexagonal shaft 62 from the closed end of the socket to the free distal end of the shaft 62 is generally equal to, or greater than, the length of the through- bore 46 of the bolt 40. The size of the socket is sufficient to accommodate the hexagonal head 42 of the bolt, and the shape of the socket is able to rotationally engage the head of the bolt. The hexagonal shaft 62 has a cross-sectional size small enough to fit within the circular majority of the bolt's through-bore 46, and small enough to fit within the hollow hexagonal key portion 54 at the end of the through-bore opposite the bolt head 42, in close fitting relation thereto so that rotation of the hex shaft 62 about its longitudinal axis will drive rotation of the hexagonally keyed free end of the bolt.

The tool 60 thus has features suitable for both unlocking the bolt 40 and reversing the threaded engagement thereof with the respective nut. The rectangular recess of the driver engagement portion of the tool body provides for attachment to the drive handle of a conventional socket wrench by receipt of a square fitting of the drive handle in the recess, and engagement of a ball detent locking mechanism of the fitting to secure the tool and handle together. It will be appreciated however that other driver arrangements for rotational driving of the tool may be employed, for example replacing the driver engagement portion with a dedicated tool handle fixed to the socket to extend in a radial direction therefrom to form a torque lever for rotating the socket and attached hex shaft.

Referring to Figures 23 or 25, the socket 72 is not of the conventional hexagonal shape normally used to engage the hexagonal head of a bolt. That is, instead of six socket periphery walls forming six straight sides delimiting the socket in each cross- sectional plane thereof, there are eighteen generally straight socket periphery walls arranged to form six identical segments 74 positioned end-to-end around the socket in each cross- sectional plane thereof. Each segment consists of three walls: a generally straight central wall 74a having two shorter end walls 74b of equal length extending from opposite ends thereof at equal but opposite oblique angles relative to the central wall. An imaginary plane parallel the central wall 74a and extending between the ends of the two end walls 74b would cooperate with the three actual walls of the segment to form a trapezoidal area adjacent the periphery of the socket in each cross-sectional plane thereof. The region bound at the center of the socket by the six imaginary planes of the six segments would be hexagonal in shape.

The perpendicular distance from the center wall of any segment to that of the respective segment disposed directly thereopposite across the socket slightly exceeds the corner to corner diameter of the hexagonal head (i.e. the diameter of a circle inscribed in the hexagonal cross-section of the bolt head) so that the socket can be fitted over the bolt head in a manner positioning each corner of the hexagonal bolt head within the trapezoidal region of a respective one of the segments, as shown in Figure 25.

The orientation of the hexagonal cross-section of the hex shaft 62 relative to the cross-section of the socket is such that each of the six corners of the hex shaft 62 points toward an intermediate location along the central wall 74a of a respective one of the six segments 74 of the socket boundary, as shown in Figure 25 where each corner of the hex shaft points to a central location on the central wall of a respective socket boundary segment 74. The hexagonal center portion of the socket cross-section that would be bound by the aforementioned imaginary planes closing off the bases of the six trapezoidal segments of the socket boundary is thus angularly offset from the hexagonal cross-section of the hexagonal shaft by thirty degrees. Full insertion of the hex shaft 62 into the hexagonally keyed end 54 of the bolt's through-bore 46 brings the socket 72 in position around the head 42 of the bolt 40, as shown in Figure 25 with the corners of the bolt head pointing toward the middle of each trapezoidal segment 74 around the socket 72 of the tool, which positions the point defined at the meeting of adjacent segments 74 a central location along a respective side of the bolt head a short distance outward therefrom.

This arrangement provides enough rotational play between this initially inserted position of the bolt head and the surrounding socket walls so that rotation of the unlock tool 60 in the lock-releasing direction (e.g. counterclockwise from the driver end of the right-handed threaded illustrated embodiment) will rotate the hexagonally keyed free end of the bolt 52 before the socket 72 rotationally engages the head 42 of the bolt 40. That is the bolt head is initially received in the tool socket in the position of Figure 25, and the tool is then rotated to turn the hex-key at the free end of the bolt shaft in the unlocking direction releasing the helical lock of the bolt, but the bolt head will only be driven by the socket once the tool has been sufficiently rotated to bring a respective one of the end-walls 74b of each trapezoidal segment 74 of the socket boundary against a respective flat-side of the bolt's hexagonal head. The bolt will rotate once sufficient torque is transmitted either by the alien key, bolt head or both. Accordingly, rotation of the tool in this direction initially unlocks the helical action of the bolt 40 before driving the bolt head in the loosening direction, and then holds this unlocked condition of the helical portion of the bolt shaft under continued rotation of the tool in this direction, thereby providing lock-release and bolt-nut disengagement functionality in a single tool.

Another embodiment (not illustrated) features a tool shaft that is longer and a socket that is hexagonal, so the user can initially insert the tool shaft far enough to reach the unlock key of the bolt without the hexagonal socket of the tool engaging the bolt head, and then can rotate the tool to release the helical lock, which brings the socket head into alignment with the bolt head based on a angular offset between the socket and shaft based on a rotational angle known to be sufficient to release the helical lock. Such an embodiment is suitable for the illustrated bolt embodiments, where the hexagonal cross-sections of the bolt head and bolt unlock key are aligned with one another. Another embodiment could reverse this, instead having the predetermined angular offset found between the bolt head and bolt unlock key, and having the socket and shaft of the tool aligned with one another. However, the illustrated embodiment is preferred, as the operation of the unlock tool is simplified, requiring only that the tool be fully slid into the bolt bore and onto the bolt head in a singular linear displacement, followed by a singular rotational action on the bolt. The other embodiments would require two stages of tool advancement, interrupted by a rotation step in-between while the shaft is engaged by the socket is not, and followed by a second further rotational action one the socket is engaged on the bolt head.

Figures 26 to 32 show an unlocking tool for similar fastener unlocking operation to that of Figures 18 to 25, but for the nut Figures 6 to 9, not the bolt of Figures 10 to 13. The tool is thus in the form of a socket body 80 having the same driver engagement portion 66 with rectangular recess 68 as the previous embodiment, but configured differently at the socket portion of the tool. Here, the tool features a two-stage socket 82 having a first socket portion 84 extending into the socket body from the end thereof opposite the driver engagement recess 68, and a socket portion 86 extending further into the socket body from the first socket portion toward the driver engagement portion 66. The first socket portion is of larger diameter than the second, as the second socket portion is intended to receive the smaller hexagonal nut portion 30 of the nut 10', while the first socket portion e needs to receive the larger hexagonal nut portion 12 of the nut 10' after initially passing over the smaller hexagonal nut portion 30 in placement of the tool over the nut from the smaller end thereof.

The cross-section of the second socket portion 86 is hexagonal like a conventional socket, but the cross-section of the first socket portion 84 has the same shape as the socket of the bolt-unlocking tool embodiment of Figures 18 to 25. Accordingly, when the two-stage socket of the tool is initially placed fully over the nut as shown in Figures 28 to 30, the smaller hexagonal portion 30 of the nut fits closely within the hexagonal second socket portion 86 of the socket, and the larger hexagonal portion 12 of the nut 10' fits within the first socket portion 84 in an orientation pointing its corners toward the centers of the trapezoidal segments 74 of the boundary of the first socket portion 84. Rotating the socket with a suitable driver, for example a ratchet handle, in the direction acting to release the helical lock of the nut 10' initially rotates the smaller hexagonal nut portion 30 in this direction to release the helical lock before the flat sides of the larger hexagonal nut portion 12 become engaged by end walls of the trapezoidal socket segments to rotate the larger hexagonal nut portion 12 in the loosening direction to complete the removal of the unlocked nut.

An alternative embodiment of the two-socket nut release tool could feature two hexagonal socket portions of suitable axial lengths relative to the those of the sections of the nut, so that angular offsetting of the socket portions of the tool relative to one another, or angular offsetting of the hexagonal portions of the nut relative to one another, would allow release of the helical lock with one socket through rotation of the smaller hexagonal nut portion before sliding the tool further over the nut to reach the larger hexagonal nut portion, where torque can then be applied to the larger hexagonal portion while maintaining torque on the unlock mechanism at the smaller hexagonal portion. Again however, this would require two stages of tool advancement and two separate rotational actions, thus complicating the use of the tool.

It will be appreciated that the particular offset angle between the two engagement portions of the release tool may be varied from the example given above, so long as the angle is sufficient to loosen the helical lock to a suitable degree before engaging the other part of the fastener for removal, and that the shape used to provide the necessary degree of play between the tool and the fastener-removing feature of the fastener component may be varied from the trapezoidal socket boundary arrangement described above.

The fastener components of the illustrated embodiments employ hexagonal shapes for cooperation with conventional tools where intended, and to employ common socket shapes where appropriate. However, it will be understood that other shapes can cooperate for rotation of a fastener by a like-shaped tool, including shapes that are not exclusively straight-sided. For example, a nut or bolt head having two opposing flats can be engaged by a crescent wrench, even if connecting surfaces between the flats are curved or otherwise unsuitable for engagement by the wrench or other tool. Other shapes or configurations are engagable by suitably designed tools, including cross-sectional shapes of various combinations of flats and curved drive portions, with even as little as one flat in an otherwise curved remainder of a nut or bolt head. For example, one known tamper resistant drive configuration is the use of axial pins or holes spaced around the longitudinal axis of the fastener component for cooperation with mating axial holes or pins on the tool to provide circumferential engagement points around the fastener axis for driven rotation thereof (e.g. as used in Snake Eyes™ fasteners). Likewise, the internal drive lock release socket of the bolt embodiments may employ shapes other than hexagonal, including known tamper resistant fastener shapes, for example the star shaped fastener engagement system marked as Torx™.

Depending on the level to which a nut of the present invention is torqued, it may be possible to disengage the helical lock of the nut and back it off the threading of the male fastener component simply through continued rotation of the smaller hexagonal end portion 30 only, thereby avoiding the need to employ two wrenches or a two-stage socket to unlock and remove the nut. That is, for most practical applications the helical lock of the nut can be disengaged and the nut backed off from the male fastener component simply through continued rotation of the end portion 30 of the nut. The unlock tool is useful where nuts are very highly torqued or when a proprietary shaped end portion is used to restrict availability of the release mechanism.

Manufacture

In manufacturing a self locking nut of the type described herein above, conventional manufacturing methods can be used to create the stock nut. Secondarily a thin cutting method is applied to form the helical slot. In the preferred embodiment this is performed by a laser, but could be performed by any other similar means including a rotating machining tool.

In a third step force is applied to the exterior of the spring helix portion of the nut to decrease its inner diameter. This could be with the simple application of a roller onto the cylindrical exterior of the spring helix or through more sophisticated non linear application of force for non cylindrical shapes. In the case where an external thread is being used, i.e. in producing a self locking bolt, the force would be applied to the interior of the spring helix in order to increase its free diameter. Alternatively, the diameter decrease may be achieved through the application of rotational force to one end of the nut while holding the other stationary

A mandrel may be used to aid in the control and forming of the above mentioned steps. The steps may be performed in different order although in the preferred embodiment laser cutting produces desirable heating of the material suitable for working the helical spring into a changed diameter.

Upon completion, other desirable physical characteristics may be imparted on the nut by any suitable form of heat treatment, and the nuts may also be provided with a surface finish of any kind, such as plating, anodizing, polishing or the like.

Figure 33 illustrates one embodiment of a CNC (computer numerically controlled) machine 100 for producing a self locking fastener component (i.e. nut or bolt) of the present invention. The machine features a horizontal base 102 whose upper end presents a dovetail tongue 104 whose length runs horizontally along the base and whose dovetail-shaped vertical cross-section flares outward in an upward direction. A slide table 106 features a flat upper face, and an underside equipped with a dovetail groove slidably engaged to the dovetail tongue 104 of the base. The lengthwise dimension of the table running along the longitudinal axis of the dovetail tongue 104 is less than the tongue length along said axis, and so the table is slidable back and forth along the dovetail tongue 04 of the base for linear displacement of the table along the longitudinal axis. Atop the table 106 is mounted a rotable chuck or workpiece support 108 configured to support a nut or bolt in a position that acts to orient the axis of the nut or bolt parallel to the horizontal longitudinal axis of the dovetail joint between the base and the table. The workpiece support 108 is rotatable about an axis that coincides with the axis of the nut or bolt when carried by the workpiece support, whereby the workpiece support is operable to rotate the nut or bolt about its axis, and the table 106 operable to linearly displace the workpiece support along the longitudinal axis of the machine, thereby displacing the nut or bolt along its parallel axis.

An upright 110 of the machine projects perpendicularly upward from the base at one end thereof and carries a slide body 112 through a linear motion interface similar to that found between the base and table. That is, a dovetail groove in a side of the slide body 112 facing the upright 110 engages the slide body to one or more vertical rails 114 of the upright to allow linear displacement or sliding of the slide body 112 up and down the upright . A downward aiming cutting laser 116 is mounted to the side of the slide body 112 opposite the upright 110 in a position and orientation directing the laser's output along a vertical path intersecting the horizontal axis of the chuck so that with the chuck positioned to hold the nut or bolt beneath the laser cutter 116, the laser will be directed toward the axis of the nut or bolt so as to cut radially thereinto. The focal length of the laser and the adjustable height of the laser cutter can be used to control the depth to which the laser will cut into the upward facing point of the nut's or bolt's periphery.

To produce a helical cut in a nut or hollowed-out portion of a bolt to create the open helical portion of the self locking fasteners described herein, CNC control is used to precisely position the table 106 at a location along the base 102 where the path of the laser is at a starting position where the desired helical cut should first cut into the fastener component. The laser cutter is activated and the chuck is rotated and while the table 106 is advanced along the base 104. With the fastener component thus being linearly displaced along its axis and simultaneously rotated thereabout, the laser forms the desired helical cut in the fastener component. If the portion of the fastener component to be helically cut has a uniform round circumference centered on the fastener component's longitudinal axis, the laser cutter remains stationary during this cutting action. On the other hand, if the vertical distance from the fastener component's axis to the point on its circumference that is aligned with the laser varies as the fastener component is rotated, the CNC machine is programmed to accordingly vary one or both of the laser cutter's focal length and vertical position on the upright to ensure that the laser cuts into the hollow interior of the fastener component, but not into or through the diametrically opposite portion of the fastener across the hollow interior thereof.

While the illustrated embodiment employs rotation and linear displacement of the fastener component, other embodiments may employ other configurations to achieve the relative linear displacement and relative angular rotation between the cutter and the fastener component relative to the axis thereof. For example, one alternate embodiment may pair rotation of the fastener component at a fixed location along the fastener axis with linear displacement of the laser along the fastener axis. Another alternate embodiment may hold the fastener component stationary and move the cutter in a helical path around and along the fastener axis. Yet another embodiment may pair linear displacement of the fastener component in an angularly fixed orientation with rotation of the cutter around the fastener axis. Where a laser cutter is used, using a rotationally-fixed downwardly pointing orientation of the laser cutter provides a simple safety solution for preventing laser exposure. Where the focal length of the laser cutter is sufficiently adjustable, or where a machine is intended for use in cutting only uniform-periphery portions of a single size of fastener, movement of the cutter toward and away from the fastener axis may not be required.

In another embodiment, not shown, the machine may use two lasers to cut the helix into the nut. This can be with one beam slightly displaced from the other (both aimed at exterior of nut), but also with one laser being targeted from the inside of the nut toward the outside and one from the outside toward the inside, which may have the advantage of creating a very clean internal cut finish. . The latter may be accomplished using specially designed, positioned or configured mirror or apparatus employing one or more reflective surfaces to direct the laser beam into the nut via the hollow region in the center of the nut and then angle, and possibly focus, the laser beam to direct it onto the inner surface of the nut, for example at a right angle to the axis of the nut. The apparatus may have a pencil-like shape that fits inside the nut and takes the laser along the pencil then reflects it at 90 degrees to the inner surface of the nut. The other laser is as described above for the illustrated embodiment, where the laser is aimed from the outside of the nut, for example at a right angle to the nut axis. The two laser configuration may present economical advantage, as two lower cost lower power lasers may be able to accomplish the same cutting effect as a higher power laser that costs more than the two lower power lasers combined. In addition, cutting from inside and outside the nut means that both edges of the cut are very clean, thereby possibly avoiding the need to provide a separate cleaning action on the nut after the cutting steps.

Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.