The present invention relates to a u-bolt comprising, a shaft having a curved portion and two ends, the ends each have a threaded surface, the curved portion is located between the ends, at least a portion of the end has a trilobular shape, and the curved portion is shaped so that a distance between the ends is shorter than the length of the end.

FIELD OF THE INVENTION

This invention relates to u-bolt assemblies, and particularly to u-bolt assemblies used for clamping, securing, or sealing one or more elements.

BACKGROUND OF THE INVENTION

U-bolts are used in many applications, including for clamping one or more elements, securing or supporting one or more elements, or sealing a connected region between two elements. U-bolts are typically utilized in combination with a cross member and a plurality of nuts.

In the typical application, a pair of nuts are threaded onto a pair of threaded ends provided on the u-bolt. As the nuts are threaded onto the ends, they exert a force upon the cross member in the direction of a curved portion on the u-bolt. The nuts are threaded onto the end until they reach a desired point on the end whereupon the cross member is located a desired distance from the curved portion. In such a manner, the nuts may be threaded so that the u-bolt and cross member cooperate to secure one or more elements located there between or clamp one or more elements located there between.

In certain applications, for example, in the exhaust system of a vehicle, there are several exhaust conduits, tubes, hoses or pipes of various shapes and lengths which are connected together to form a fluid path for the exhaust gas. In addition to being clamped, supported or secured, it may also be important that the connected region be provided with a substantially leak-proof and mechanically secure joint. For these applications, typically, the cross member is provided with a concave portion which opposes a corresponding concave curved portion on the u-bolt. As the cross member and u-bolt are forced towards each other through the use of a pair of nuts that are threaded on the ends of the u-bolt, the corresponding concave portions cooperate to reduce or eliminate leakage from the connected region. Sometimes it is still difficult to achieve uniformly leak-proof joints because the narrowness of such u-bolts and cross members makes it difficult to completely cover and connected region. This problem can be overcome by using one or more relatively wide shims in combination with a u-bolt and a cross member to effectively and easily seal the connected region.

Whatever the application, for most, it is often crucial that the nuts do not loosen or disengage once they are threaded onto the end whereby an element or elements are secured, clamped, or sealed. If the nuts back off the end, a safety hazard may arise because the element or elements cease to be secured, supported, clamped, or sealed. The present invention is directed to overcoming this and other disadvantages inherent in prior-art systems.

SUMMARY OF THE INVENTION

The scope of the present invention is defined solely by the appended claims, and is not affected to any degree by the statements within this summary. Briefly stated, a u-bolt comprising, a shaft having a curved portion and two ends, the ends each have a threaded surface, the curved portion is located between the ends, at least a portion of the end has a trilobular shape, and the curved portion is shaped so that a distance between the ends is shorter than the length of the end.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Turning now to the drawings,FIG. 1shows a stud as a u-bolt5of a preferred embodiment of the present invention. The u-bolt5is composed of a metal, preferably aluminum. According to one aspect of the present invention, the metal is copper. According to another aspect of the present invention, the metal is iron.

In one aspect of the present invention, the metal is an alloy. According to another aspect of the present invention, the metal includes ferrous and non-ferrous materials. According to another aspect of the present invention, the metal is a steel. By way of example and not limitation, the steel is a stainless steel, such as A286. In one embodiment of the present invention the steel is a low carbon steel, such as 1010. In another embodiment of the present invention, the steel is a medium carbon steel, such as 1038, 1541, 4037, 8640, or 8650. In yet another embodiment of the present invention, the steel is a high carbon steel.

Those with skill in the art will also appreciate that the metal is a super alloy. According to one aspect of the present invention, the super alloy is bronze; according to another aspect of the present invention, the super alloy is a high nickel material. According to yet another aspect of the present invention, the u-bolt5is composed of martensitic material, such as 410 or 416. According to still another aspect of the present invention, the u-bolt5is composed of austenitic material, such as 302HQ, 304, or 305. According to another aspect of the present invention, the metal is a ferritic material.

FIG. 1depicts the u-bolt5of the presently preferred embodiment of the present invention. As shown therein, the u-bolt5includes a shaft10that is provided with a curved portion16and two ends20. The curved portion16of the preferred embodiment is a round bend. As shown inFIG. 1, the curved portion16of the preferred embodiment is provided with a radius17.

As shown inFIG. 2, in an alternative embodiment the shaft10is provided with a curved portion16that is a square bend. The curved portion16of this embodiment is provided with radiuses18.

As shown inFIGS. 1 and 2, the curved portion16is located between the pair of ends20. Also shown therein, the curved portion is shaped so that there is a distance D between the ends20. The distance D is related to a length L of the shaft10, which is shown inFIG. 3. The curved portion16is shaped so that the distance D between the ends20is shorter than the length of the shaft10.

At least one of the ends20is provided with a contoured outer surface. Preferably both ends20are provided with a contoured outer surface. In the preferred embodiment, ends20are each provided with an identically contoured outer surface.

FIG. 1depicts an end20of the preferred embodiment of the present invention composed of a plurality of outer surfaces. As illustrated inFIG. 1, the end20provides a suitable location for at least one of a plurality of outer surfaces. A lower cylindrical end element22of the preferred embodiment includes a plurality of threads40. Located adjacent to the threads40is an unthreaded surface30.

The outer surfaces of the present invention perform a plurality of functions. In the preferred embodiment, the surface composed of a plurality of threads40functions to couple the u-bolt5to another structure. This function is accomplished through the interaction of the plurality of threads40and the cooperating threads of a nut body62.

The end20is composed of at least one of a plurality of end elements. According to one aspect of the present invention, the end element is cylindrical in shape. According to another aspect of the present invention, the end element is conical in shape. According to yet another aspect of the present invention, the end element is solid.

FIG. 1depicts the preferred embodiment of the present invention composed of a plurality of end elements. The end20includes an upper cylindrical end element21, a lower cylindrical end element22, and a conical end element23. In the preferred embodiment, the upper cylindrical end element21is joined to the lower cylindrical end element22via the conical end element23.

The u-bolt5of the present invention is provided with a plurality of outer surfaces. According to one aspect of the present invention, the outer surface is an unthreaded surface30. According to another aspect of the present invention, the outer surface is a threaded surface40.

FIG. 4depicts the threaded surface40in greater detail. As shown therein, the threaded surface40is provided with a plurality of thread configurations41,42,43. The threaded surface40is provided with a locking thread41.FIG. 5depicts a cross-sectional view of a plurality of locking threads41in greater detail. As depicted inFIG. 5, the locking thread41is provided with a plurality of angled surfaces44,46. In the preferred embodiment, the locking thread41is provided with a first angled surface44and a second angled surface46. Advantageously the first angled surface44is at an angle100with respect to the second angled surface46ranging between 30° to 70°, preferably 60°.

Located between the first angled surface44and the second angled surface46is a root surface45. The root surface45of the locking thread41includes a root diameter. The root surface45is at an angle47with respect to an imaginary horizontal line A running along the axis of the shaft20. Preferably, the angle47is between 4° and 8°. The root surface45has a width that is greater than that found in a conventional thread and is configured so that the locking thread41converges to the head56.

The locking thread41is configured to cooperate with the threads64of a nut body52, also referred to herein as a female threaded member. As the nut body52is torqued onto the shaft20, the root surfaces45within the locking threads41exert a force on the threads64of the nut body52. As depicted inFIG. 4, in cases where the threads64of the nut body52include a metal, the root surface45exerts a force upon the thread64of the nut body52so that the metal flows upward on a flank48of the thread64.

Referring now toFIG. 7, the threads64of the nut body62are re-formed so that the threads64generally conform to the configuration of the locking thread41. As depicted inFIG. 7, the flank48of the thread64of the nut body62is re-formed so that it is in contact with at least one of the angled surfaces44,46of the locking thread41.FIG. 7further depicts the threads64of the nut body62re-formed so that a greater surface area is in contact with the root surfaces45on the end20.

As depicted inFIG. 4, a plurality of Vee-shaped threads44, also referred herein as conventional threads, are located adjacent to the plurality of locking threads41and provided with a thread root129. The Vee-shaped threads44include a root diameter and a crest diameter. As depicted inFIG. 2, the root diameter of the locking thread41is greater than the root diameter of the Vee-shaped threads44. A cross-sectional view of a plurality of Vee-shaped threads42is depicted in greater detail inFIG. 8. As shown therein, a Vee-shaped thread42is provided with a first side50and a second side51. The sides50,51abut one another and are configured to form a Vee shape. The first side50is at an angle with respect to the second side51, preferably ranging between 30° and 90°.

FIG. 4further depicts a plurality of curved threads43located adjacent to the Vee-shaped threads42. In this application, the term curved threads43is also referred to herein as guide threads.FIG. 9depicts a cross-sectional view of a plurality of curved threads43in greater detail. According to one aspect of the present invention, the curved threads43are configured to prevent cross-threading. According to another aspect of the present invention, the curved threads43are configured to orient the threads64of a nut body52so that the threads64align with the threaded surface40on the shaft20.

As shown inFIG. 9, the curved threads43are provided with at least one curved surface31. In the preferred embodiment, the curved threads43are provided with a first side50and a second side51. The curved surface31is located between the first side50and the second side51. As shown inFIG. 9, the first side50is at angle with respect to the second side51, preferably ranging between 30° and 90°. Alternatively, as shown inFIG. 10, the first and second sides50,51are curved.

FIG. 11depicts a cross-sectional view of an alternative threaded surface40. As shown therein, the threaded surface40includes a plurality of guide threads53. The guide threads53include a crest diameter. As illustrated inFIG. 4andFIG. 11, the guide threads43,53,63, differ from the conventional threads on the shaft20in that the conventional threads are provided with a crest diameter (referred to herein as a “first crest diameter”) that is, at least in part, greater than a crest diameter of the guide threads (referred to herein as a “second crest diameter”). According to one aspect of the present invention, the guide threads53are configured to prevent cross-threading. According to another aspect, the guide threads53are configured to orient the threads64of a nut body52so that the threads64align with the threaded surface40on the shaft20. As shown inFIG. 9, the guide threat53are located at an end of the shaft20and are provided with a reduced diameter relative to the Vee-shaped threads42. In this application, the term “guide means” refers to threads on a shaft20that have a crest diameter that is, at least in part, less than the crest diameter of the conventional thread on the shaft20. Guide means encompasses structures on a shaft20that generally align the threads of the shaft20with those of a female threaded member.

A plurality of plateau threads63are located adjacent to the guide threads53. In this application, the term plateau threads63is also referred to herein as guide threads. As depicted inFIG. 11, the plateau threads63are provided with a plurality of plateaus55. The plateaus55are shaped to prevent cross-threading and to orient the nut body so that the threads64align with the threaded surface40on the shaft20. In the embodiment depicted inFIG. 11, the plateaus55are conically or frusto-conically shaped, preferably to provide a ramped cross-sectional profile.

Referring now toFIG. 12, a bottom cross-sectional view of the end20is shown. The end20is advantageously provided with a trilobular shape; however a circular or ovular shape could be used.

The u-bolt5is fabricated through a plurality of processes. According to one aspect of the present invention, the u-bolt5is machined. According to another aspect of the present invention, the u-bolt5is hot formed or forged. According to yet another aspect of the present invention, the u-bolt5is fabricated through casting. According to still another aspect of the present invention, the u-bolt is warm formed or forged. The preferred embodiment of the present invention is cold formed or forged (also known as “cold head”).

In the preferred embodiment the u-bolt is fabricated from steel having a preferred orientation or texture. The u-bolt5depicted inFIGS. 13 and 13Ais provided with a longitudinal axis12. The u-bolt5is made of high strength steel having steel grains15with a preferred orientation or texture. In the preferred orientation, the steel grains15of u-bolt5are substantially parallel to the longitudinal axis12(seeFIG. 13A).

U-bolts according to one embodiment of the present invention are made from blanks of high strength steel having grains with a texture parallel to the longitudinal axis of the blank such that the orientation of these textured grains will be substantially parallel to the resulting u-bolt's longitudinal axis after either cold or warm forming. In another embodiment, the u-bolts are made from blanks of high strength steel having grains with a random orientation such that only the grains which are deformed during the forming operation (i.e., from blank to u-bolt) are textured.

In most forms, u-bolts according to the present invention are formed from blanks of high strength steel having a yield strength of at least about 90,000 psi, and preferably at least about 130,000 psi, and a tensile strength of at least about 120,000 psi, and preferably at least about 150,000 psi. Such blanks are then either cold formed at a temperature of less than 300 degrees F. or warm formed within a temperature range from about 300.degrees F. up to about the steel's recrystallization temperature into u-bolts with predetermined geometric configurations.

Whatever forming temperature is used, detrimental recrystallization should be avoided. Forming (i.e., permanently deforming) the blank at a temperature which avoids complete recrystallization produces a u-bolt with steel grains having a preferred orientation or texture. In an alternative embodiment, the method of the present invention for making high strength steel u-bolts includes providing a blank of high strength steel having the yield and tensile strength as given above and a preferred orientation which is parallel to the longitudinal axis of the blank.

The temperature at which the u-bolt is formed is related to the chemical composition of the steel used. When the blank is cold formed into a u-bolt, the high strength steel may be exemplified by the following composition, by weight percent:carbon: about 0.30 to about 1%;manganese: about 2.0 to about 2.5%;vanadium: up to about 0.35%; andiron balance.

In a more preferred form, the high strength steel has the following composition, by weight percent:carbon: about 0.50 to about 0.55%;manganese: about 2.0 to about 2.5%;vanadium: up to about 0.03% to about 0.15; andiron balance.

When a warm forming process is used, the high strength steel may be exemplified by the following composition, by weight percent:carbon: about 0.30 to about 0.65%;manganese: about 0.30 to about 2.5%;vanadium: up to about 0.35%iron balance.

In a more preferred form, the high strength steel has the following composition, by weight percentage:carbon: about 0.50 to about 0.55%;manganese: about 1.20 to about 1.65%;vanadium: about 0.03 to about 0.15%iron balance.

In the above compositions, columbium, silicon, and aluminum may be substituted in whole or in part for vanadium; however, vanadium is preferred for strength and ductility purposes.

When the blank is cold formed into a u-bolt according to the present invention, the yield strength and tensile strength of the u-bolt are substantially the same or greater than the blank and no subsequent annealing step is required. When the blank is warm formed or cold formed into a u-bolt, the u-bolt thus produced needs no further strengthening.

Most commercially available steels are polycrystalline (i.e., made of many crystals or grains). Each crystal or grain has metal atoms which are arranged in a pattern which is generally repeated throughout the grain (i.e., crystal structure). The grains of a steel part can have a random orientation, a preferred orientation, or a combination of both, depending on a number of factors, including the temperature at which the steel is formed.

When steel is hot formed, such as by hot forging, the grains of the steel are provided with a random orientation. Steel is hot formed when it is plastically or permanently deformed above its recrystallization temperature. Forming above the recrystallization temperature not only prevents the formation of textured grains but also eliminates any preexisting texturing. That is, the orientation of each grain's crystal structure differs from grain to grain. Such a random orientation typically results in the mechanical properties of the steel being isotropic (i.e., having the same properties in all directions).

In contrast to hot forming, cold forming or warm forming a steel causes the crystal structure of the affected steel grains (i.e., those grains which are permanently deformed) to orient themselves according to the way they are deformed (i.e., in a preferred orientation). With warm forming, the steel is generally preheated to a temperature below its recrystallization temperature before being permanently deformed. Cold forming is generally performed at about room temperature up to about 300 degrees F. Warm forming or cold forming generally results in the mechanical properties of at least the deformed portion of the steel being anisotropic in nature. Grains which are textured are stronger (i.e., have a higher modulus of elasticity) along the direction of the preferred orientation than grains having a random orientation.

For example, cold rolling or extruding a blank of steel bar stock will cause the grains of the steel bar to elongate and reorient themselves into a preferred orientation which is parallel to the longitudinal axis of the bar stock (seeFIG. 13A). Such an orientation will result in the bar being strongest along its longitudinal axis. Therefore, a forming operation which either imparts a texture to the high strength steel grains or leaves previously textured grains intact is desirable. Cold or warm forming not only allows preexisting textured grains to be retained, but such treatment may impart additional texturing.

The blank of high strength steel which is used as the starting piece in the present invention is produced by any suitable method known in the art. In-one form, the high strength steel of the blank used for making u-bolts according to the present invention has been hot reduced and cold drawn to provide the blank with the yield strength and tensile strength stated above as well as grains with a preferred orientation parallel to the longitudinal axis of the blank. An example of such a method is disclosed in U.S. Pat. No. 3,904,445 to the Hugh M. Gallagher, Jr., the disclosure of which in its entirety is incorporated herein by reference.

The '445 patent discloses a processing sequence to produce a high strength steel bar stock of the type particularly useful for producing threaded fasteners, including U-bolts. In the disclosed process, a steel, having chemistry falling within certain disclosed ranges, is subjected to a standard hot reducing operation to within 10%-15% of final gauge. The hot reduced bar stock is then cut or severed into individual lengths for rapid air cooling. At this point, the bar stock produced has a fine grain structure between about ASTM No. 5-8, with the grains having a random orientation. Thereafter, the individual lengths of hot reduced bar stock are subjected to a cold forming operation to final gauge. The final step is a controlled stress relieving step to reduce residual stresses built up from the cold finishing. The stress relieving leaves the mechanical properties of the metal relatively unchanged. This stress relieving step comprises heating the lengths of bar stock to between about 500.0 degree.-850.0 degree. F. for about one hour, but may or may not be necessary. Thus, such bar stock may be used to form the starting blank of high strength steel for making a u-bolt according to the present invention.

In other forms, the high strength steel of the blank used for making u-bolts according to the present invention has been provided with the yield strength and tensile strength stated above but not grains with a preferred orientation parallel to the longitudinal axis of the blank. However, because cold and warm forming can strengthen the steel at the location of the permanent deformation, even a blank or bar of steel initially having randomly oriented grains can be strengthened by cold or warm forming at the portion or segment which is permanently deformed. Thus, a steel bar or blank, with a random grain orientation, which is permanently bent by cold or warm forming can be stronger along the curved portion than at any other point along its length. Likewise, a steel bar with grains having a preferred orientation parallel to the bar's longitudinal axis which is permanently bent by cold or warm forming can also be stronger along the curved portion than at any other point along its length. When the bar is bent, the textured grains of the steel bar also curved portion, following the longitudinal axis (seeFIG. 13A). For any given degree of permanent deformation, however, cold forming has a greater strengthening effect than warm forming.

Cold forming a curved portion in a length of bar stock is less severe than other cold forming techniques, such as upsetting or extruding, which may cause cracks or fractures in the finished u-bolt. Consequently, in the preferred embodiment, the blank is provided with a composition that is better suited to being subjected to cold forming techniques, such as upsetting or extruding. This method for making a high-strength u-bolt includes providing a blank of high-strength steel material having a microstructure of fine pearlite in a ferritic matrix, a tensile strength of at least about 120,000 psi and preferably at least about 150,000 psi, and a yield strength of at least about 90,000 psi, and preferably at least about 130,000 psi. Pearlitic constituents are generally considered to be “fine” when their lamellae are not resolvable at an optical magnification of about 1000 times.

In one form, the high-strength steel material utilized as the blank has been hot reduced and cold drawn to provide the blank having the mechanical properties of tensile strength and yield strength stated above.

The high-strength steel material used to make the blank has the following composition, by weight percent:carbon about 0.30 to about 0.65%;manganese about 0.30 to about 2.5%;at least 1 ferrous grain refiner from the group consisting of aluminum, niobium, titanium and vanadium, and mixtures thereof, in an effective amount up to about 0.35%; andiron balance.

In a more preferred form, the high-strength steel material has the following composition, by weight percent:carbon about 0.40 to about 0.55%;manganese about 0.30 to about 2.5%;at least 1 ferrous grain refiner from the group consisting of aluminum, niobium, titanium and vanadium and mixtures thereof, in an effective amount up to about 0.20%; andiron balance.

In a still more preferred form, the high-strength steel material has the following composition, by weight percent:carbon about 0.50 to about 0.55%;manganese about 1.20 to about 1.65%;at least 1 ferrous grain refiner from the group consisting of aluminum, niobium, titanium and vanadium, and mixtures thereof, in an effective amount from about 0.03 to about 0.20%; andiron balance.

In a further preferred form, the high-strength steel material has the following composition, by weight percent:carbon: about 0.50 to about 0.55%;manganese: about 1.20 to about 1.65%;at least 1 ferrous grain refiner from the group consisting of aluminum, niobium, titanium and vanadium, and mixtures thereof, in an effective amount from about 0.03 to about 0.15%; andiron balance.

While aluminum, niobium (i.e., columbium), titanium, and vanadium act as grain refiners, vanadium is the most preferred of the grain refiners. Furthermore, it should be understood that the compositions listed and claimed herein may include other elements which do not impact upon the practice of this invention.

The blank, having a composition and mechanical properties of tensile strength and yield strength as given above is thereafter cold formed using such techniques as roiling, upsetting, forging, or extrusion at a temperature between ambient or room temperature up to less than about 300.degree. F., and preferably at about ambient temperature, to provide a u-bolt5having a desired geometric configuration, whereby the mechanical properties of tensile strength and yield strength of the u-bolt5are substantially the same or greater than the blank. The formed u-bolt5, with the mechanical properties of tensile strength and yield strength given, is preferably produced without the need for further processing steps, such as a final stress relieving step, to improve toughness. However, for certain applications of the u-bolt, a stress relieving step may be necessary.

The blank of high-strength steel material having a tensile strength of at least about 120,000 psi and a yield strength of at least 90,000, which is used as the starting piece in the present invention, is produced by any suitable method known in the art. One such method is disclosed in the '445 patent. Thus, such bar stock, with and without further stress relieving may be used to form the starting high-strength steel blank for this alternative method.

The preferred process of cold forming the u-bolt begins with a blank fabricated in accordance with the aforementioned preferred method. The blank is upset by being rolled or run through a series of dies or extrusions which elongate the blank into a rod that is provided with a generally cylindrical shape. Then, the portion of the rod that is to be used as the end20is extruded to have a trilobular cross section. Then the threads40are rolled with a sectional die. Preferably, the curved threads43are rolled first. Then, the Vee-shaped threads42are rolled. Finally, the locking threads41are rolled. Subsequently, the rod is bent to form a u-bolt with the desired geometric configuration.

In an alternative process, the u-bolt begins with a blank fabricated in accordance with the aforementioned alternative method. The blank is cold formed or warm formed and upset by being rolled, which elongates the blank into a rod that is provided with a generally cylindrical shape. Then the threads40are rolled with a sectional die. Preferably, the curved threads43are rolled first. Then, the Vee-shaped threads42are rolled. Finally, the locking threads41are rolled. Subsequently, the rod is bent to form a u-bolt with the desired geometric configuration.

In another alternative process the cold forming of the u-bolt begins with a metal wire or metal rod which is drawn to size to provide a blank. After the wire or rod is drawn to size, the blank is upset by being rolled or run through a series of dies or extrusions which elongate the blank into a rod. Then, the portion of the rod that is to be used as the end20is extruded to have a trilobular cross section. Then the threads40are rolled with a sectional die. Preferably, the curved threads43are rolled first. Then, the Vee-shaped threads42are rolled. Finally, the locking threads41are rolled. Subsequently, the rod is bent to form a u-bolt with the desired geometric configuration.

In the case of a carbon steel being used as a material in the u-bolt5, it is desirable to heat treat the u-bolt5through a quench and temper. In the case of a stainless steel being used, such as A286, it is desirable to put the u-bolt5through a solution anneal and then age hardening in a furnace via ASTM A453.

To finish the u-bolt5, it is coated with a low friction coating via a dip and spin. However, a plating, an organic coating, PTFE, a dacromet coating, an inorganic coating, dorraltone, a zinc coating, such as an electro zinc coating, a coating containing phosphate and oil, a ceramic coating, or a coating of waxes and oils may all be used.

The u-bolt5is configured to operate with a nut52or a nut-washer assembly99. Referring now toFIG. 14, the presently preferred embodiment of the nut-washer assembly99is depicted. As depicted therein, the nut-washer assembly99is provided with a nut52. The nut52is preferably fabricated from steel, preferably a carbon steel, such as 1020 to 1045 steel.

The nut52is preferably forged. The steel is first heated to 2100° F., cut into segments, and pressed so that it is circular and larger in diameter. Then a portion of the inner surface and a torque transmitter66are forged. Thereafter, another portion of the inner surface is punched out and the nut52is then heat treated to an average hardness ranging between26and36on the Rockwell C scale, preferably31.

The washer54is preferably fabricated from an alloy grade steel, such as 4140 steel. However, those skilled in the art will appreciate that a medium carbon steel such as 1020 to 1045 steel may be used. Similar to the nut52, it is preferred that the washer54be fabricated through forging. The steel is first heated to 2100° F., cut into segments, and pressed so that it is circular and larger in diameter. Then, an annulus is formed and punched out. The washer54is heat treated to an average hardness ranging between28and42on the Rockwell C scale, preferably36.

The nut52and washer54are assembled together. The nut52is mated with the washer54and then a collar on the nut is flared out. Those skilled in the art will appreciate that the flare provides a lead for the threads. Then, a tap is sent down through the nut52, and threads are cut into the nut52. The threads preferably have a diameter in the range of M8 up to an M30.

The nut52and/or the washer54may advantageously be provided with a coating. Preferably, the coating is of a formulation that prevents rust and/or corrosion; however, other coatings may be used. By way of example, and not limitation, the coating may be a formulation that reduces friction. In one embodiment, the coating reduces friction between the nut and the washer. In another embodiment, the coating reduces friction within the threads.

Those skilled in the art will appreciate that various chemical compounds may be used as suitable coatings. In one embodiment, polytetrafluoroethylene or PTFE is used. In another embodiment, a zinc coating is used. In yet another embodiment, a water-based coating dispersion containing metal oxides and/or aluminum flakes is used.

In the preferred embodiment the nut52is provided with a nut body62. As depicted inFIG. 14, the nut body62is internally threaded at64. The internal threads at64preferably extend to an internal portion of a skirt68.

The nut body62is provided with a plurality of curved and flat surfaces. As shown inFIG. 14externally around the periphery of the nut body62is a torque transmitter66. The torque transmitter66of the preferred embodiment comprises a plurality of surfaces. As depicted inFIG. 14, the plurality of surfaces are arranged in the preferred hexagonal shape.

The nut body62is provided with an annular surface72. The annular surface72is located at the bottom of the nut body62, above a skirt68. Referring now toFIG. 15, the annular surface72is preferably generally frusto-conical in shape. However, those skilled in the art will appreciate that the annular surface72can be spherically concave, spherically convex, or flat, without departing from the scope of the invention. By way of example and not limitation, the annular surface72can be flat where the application does not require a washer54.

The annular surface72can be fabricated using any desired technique. In the preferred embodiment, the annular surface72is preferably fabricated by cold forging. The cold forging is preferably accomplished through the use of a die insert. The die insert is preferably machined to the desired shape using conventional ball end mill techniques.

In an alternative embodiment the annular surface72is undulating in shape. The annular surface72of this embodiment is configured to cooperate with a bearing surface84. As depicted inFIG. 16, the annular surface74is undulating in shape. The annular surface72therein is provided with an annularly extending series of surfaces, which provide a uniform undulation around the entire annular surface72.

FIGS. 16 and 17depict yet another alternative embodiment of the present invention. As depicted therein, the annular surface72is provided with a plurality of lower peaks. The lower peaks are provided as plateaus74.

The plateaus74are preferably generally spherically convex. The plateaus74are provided with the same radius as the valleys122on the bearing surface84on the washer54. The plateaus74are formed in the cold forging process so that they are all convex and lie on the surface of an imaginary sphere whose center is on the axis of the nut body62. The radius of that sphere ranges from 0.1 inches to 2.00 inches.

The plateaus74are adjacent to a plurality of faces73. Each plateau74is adjacent to a pair of faces73that are oppositely inclined. The annular surface72of this alternative embodiment is provided with an annularly extending series of faces73, which form a uniform undulation around the entire surface. The faces73are configured to be complementary with corresponding faces116on the bearing surface84on the washer54. The faces73are provided with the same radius as the faces73on the bearing surface84.

As depicted inFIGS. 16 and 17, the faces73are preferably generally spherically convex. Each face73is formed so that it is convex and is curved both radially and circumferentially with respect to the nut body62.

Each face73is adjacent to a valley75. Each valley75is adjacent to a pair of faces73. The valleys75are configured to be narrower than valleys122on the bearing surface84. As depicted inFIGS. 16 and 17, the valleys75are generally spherically convex and have a predetermined depth. In one embodiment, the depth is dimensioned according to the number of threads on the nut.

The valley75and adjacent faces73of the alternative embodiment provide a generally inverted Vee-shape profile. The Vee-shaped profile provides the plateaus74with a height. Advantageously, the height is dimensioned according to the distance between the plateau segment74and the valley75. In the embodiment shown herein, the height equals the vertical distance between the plateau74and the valley75. The height is preferably slightly greater than the clearance between the threads at64and those on a end, such as end20or21, when the fastener assembly50is in place. In this alternative embodiment, the height ranges between 0 inches and 0.030 inches

In an alternative embodiment, the height is dimensioned according to the number of threads, measured axially, per inch on the nut. Advantageously the height is related to the number of faces73or faces116. By way of example and not limitation the height, in inches, is proportional to the number of threads per inch and the number of Vee-shaped undulations. In the preferred embodiment, the height is proportional to the product of the number of threads per inch and the number of Vee-shaped undulations. The height of this alternative embodiment ranges up to approximately 0.04167 of an inch.

The nut52is preferably provided with a skirt68. The skirt extends axially away from the nut body62at the inner end of internal threads64. The skirt68is configured to cooperate with a washer54. The skirt68is shaped to retain a washer54in a loose relationship. In the preferred embodiment, the skirt68is adapted to extend axially from the annular surface72into the generally cylindrical washer body82whereupon a collar85is formed outwardly under an undercut shoulder within the washer body82to loosely but securely hold the washer54and nut52together.

As shown inFIG. 17, depending from the nut body62is a uritarily formed annular skirt68. As shown inFIG. 19, the skirt68is provided with a collar85that functions to retain the washer54. Those skilled in the art will appreciate that, for an application that does not require a washer54, the nut52can be fabricated without the skirt68without departing from the scope of the present invention.

Referring now toFIG. 14, the presently preferred embodiment of the nut-washer assembly99is depicted. As depicted therein the nut-washer assembly99is provided with a washer54. The washer54is preferably fabricated from steel. The steel is preferably medium carbon steel. The steel is preferably forged and then heat treated to an average hardness of33on the Rockwell C scale

As shown inFIG. 14, the washer52is provided with a washer body82. In the preferred embodiment, the washer body82is generally annular in shape. As shown inFIG. 14, a portion of the washer body82is generally cylindrical.

The washer body82is provided with a bearing surface84. The bearing surface84can be fabricated using any desired technique. The bearing surface84is preferably fabricated by cold forging. The cold forging is preferably accomplished through the use of a die insert. The die insert is preferably machined to the desired shape using conventional ball end mill techniques.

As depicted inFIG. 20, the bearing surface84is preferably located on the inner end of the washer body82. As depicted therein, the bearing surface84is preferably generally frusto-conical in shape. However, those skilled in the art will appreciate that the bearing surface84can be spherically concave, spherically convex, or flat, without depart from the scope of the invention.

In an alternative embodiment the bearing surface84is undulating in shape. The bearing surface84of this embodiment is configured to cooperate with an annular surface72. As depicted inFIG. 21, the bearing surface84is undulating in shape. The bearing surface84therein is provided with an annularly extending series of surfaces, which provide a uniform undulation around the entire bearing surface84.

FIGS. 21 and 22depict yet another alternative embodiment of the present invention. As depicted therein, the bearing surface84is provided with a plurality of upper peaks of an undulation. The upper peaks are provided as plateaus118. The plateaus118are generally spherically concave

The plateaus118are adjacent to a plurality of faces116. Each plateau74is adjacent to a pair of faces116. The bearing surface84of this alternative embodiment is provided with an annularly extending series of faces116, which form a uniform undulation around the entire surface. The faces116are configured to correspond to faces73on the annular surface72. As depicted inFIGS. 21 and 22, the faces116are generally spherically concave.

Each face73is adjacent to a valley122. Each valley122is adjacent to a pair of faces116. The valleys122are configured to be wider than valleys75on the annular surface72.

As depicted inFIGS. 21 and 22, the valleys122are generally spherically concave and have a predetermined depth. In one embodiment, the depth is dimensioned according to the number of threads on the nut. The valleys122are formed in the forging process so that they are all concave and lie on the surface of an imaginary sphere whose center is on the axis of the washer body82. The radius of that sphere ranges from 0.1 inches to 2.00 inches. As such, it will be seen that the plateaus74on the nut body62are perfectly complementary in shape to the valleys122on the washer body82.

The valley122and adjacent faces116of the alternative embodiment provide an inverted Vee shape profile. The Vee shaped profile provides the plateaus118with a height. Advantageously, the height is dimensioned according to the distance between the plateau74and the valley75. In the embodiment shown herein, the height equals the vertical distance between the plateau118and the valley122. The height is preferably slightly greater than the clearance between the threads at64and those on a end, such as end20or21, when the fastener assembly50is in place. In this alternative embodiment, the height ranges between 0 inches and 0.030 inches.

In an alternative embodiment, the height is dimensioned according to the number of threads, measured axially, per inch on the nut. Advantageously the height is related to the number of faces73or faces116. By way of example and not limitation the height, in inches, is proportional to the number of threads per inch and the number of Vee-shaped undulations. In the preferred embodiment, depicted inFIGS. 21 and 22, the height is proportional to the product of the number of threads per inch and the number of Vee-shaped undulations. The height of this alternative embodiment ranges up to approximately 0.04167 of an inch.

In the preferred embodiment, washer body82is provided with a clamping surface86. As depicted inFIG. 20, the clamping surface86is provided on the outer end88of the washer body82. In the presently preferred embodiment, the clamping surface86is generally flat.

As depicted inFIGS. 21 and 24, in an alternative embodiment, the washer54is provided with an ear108. The ear108is configured to cooperate with a u-bolt5. The ear108cooperates with a slot49provided on at least a portion of the u-bolt5. The ear108is of a size and shape suitable to slide loosely in an axially elongated slot49formed on one side of the threaded end section of a u-bolt5. The ear108preferably cooperates with the slot49to prevent the washer54from rotating with respect to the u-bolt5.

FIG. 25depicts an ear108extending inward from end face88washer body82.FIG. 22depicts the ear108extending inwardly of the base of the washer body82, opposite a flange92. Referring now toFIG. 26, the ear108is depicted cooperating with a slot49on a portion of a u-bolt5.

Those skilled in the art will appreciate that the invention contemplates the use of other conventional means for preventing washer rotation. In the alternative, a flat may be formed on the u-bolt5and a corresponding flat formed inwardly of the washer body82.

FIG. 27depicts yet another alternative embodiment of the present invention. As shown therein, the washer54is provided with a flange92. The flange92extends outward from the washer body82. In this alternative embodiment, the flange92is between 0.05 inches and 0.12 inches thick.

In another alternative embodiment the flange92is provided with a plurality of slots formed inwardly from its outer edge, at regular intervals around the flange92. The slots permit intervening flange sections102to resiliently flex, albeit only slightly, when the clamping surface86is forced against a surface and is under the desired load.

FIGS. 27 and 28and depict the flange92provided with slots in the form of a plurality of cut-outs98. The cut-outs98provide the flange92with a plurality of flange sections102. Advantageously, the flange sections102are configured to flex axially. The flange sections102are configured to flex an axial distance which is slightly greater than the clearance between the threads on the u-bolt and the threads on the nut52.

In the alternative embodiment depicted inFIGS. 27 and 28, the cut-outs98are generally U shaped. However those skilled in the art will appreciate that this invention contemplates utilizing cut-outs98with alternative shapes.

In the alternative embodiment depicted inFIGS. 27 and 28, the flange92is provided with six cut-outs98yielding six flange sections. However those skilled in the art will appreciate that any number of cut-outs98may be employed. In particular, those skilled in the art will appreciate that it is advantageous to utilize more or less than six cut-outs98, depending on the size and thickness of the flange92.

In yet another alternative embodiment of the present invention, the washer54is provided with a clamping surface86. Referring toFIG. 33, at least a portion of the clamping surface86is located on the flange92. As shown therein, the clamping surface86is located on the bottom of the flange92and the outer face88of the washer body82.

In this alternative embodiment, the slightly concave clamping surface86on the bottom of the washer54forms what approximates a shallow frustum of a cone. The clamping surface86is preferably inclined upwardly from the outer periphery94of the bottom of the washer flange92toward the inner periphery96of the body82. As best depicted inFIG. 34, the clamping surface86is at an angle101with respect to imaginary line C, which runs perpendicular to the axis of the nut52. Angle101ranges from 0° to 3°. In this alternative embodiment, the angle101is 2°.

In another alternative embodiment, the clamping surface86is provided with a plurality of depressions104. Advantageously, the plurality of depressions104provide the clamping surface86with clamp segments106. Advantageously, the clamp segments106are configured to flex axially.

Referring toFIG. 28, the depressions104are located on the bottom of the flange92and the outer face88of the washer body82. In this alternative embodiment, the depressions104extend radially inward from corresponding cut-outs98. As depicted inFIG. 28, the clamping surface86is provided with six depressions104that are generally Vee-shaped. However, those skilled in the art will appreciate that any number of depressions may be employed.

In the alternative embodiment depicted inFIG. 28, the depressions104effectively separate the annular clamp surface86into six clamp segments106that are provided with an arcuate shape. The arcuate outer extremities of the clamp segments106are located between the cut-outs98and are able to resiliently flex axially of the washer54.

FIG. 35depicts the clamping surface86of an alternative embodiment. As shown therein the clamping surface86is provided with a plurality of protrusions57. The protrusions57provide the clamping surface86with a higher frictional coefficient.

The protrusions57are configured to cooperate with a surface on which the clamping surface86is fastened. Advantageously, the protrusions57cooperate with the surface to prevent the washer54from rotating with respect to the surface that is being fastened.FIG. 35depicts a clamping surface86that is provided with eight (8) protrusions; however, a clamping surface86may be provided with more than eight (8) protrusions, such as twelve (12) protrusions. Alternatively, the nut body62may be provided with a clamping surface86having protrusions57rather than the washer54as depicted inFIG. 39.

FIG. 33depicts the nut52and washer54assembled in the preferred embodiment. As depicted therein, the nut52and washer54are preferably assembled by inserting the skirt68into the washer54, whereby the annular surface72is opposed to the bearing surface84. Thereafter, at least a portion of the skirt68is forced outward to provide the collar85. The collar85is configured to underlie a portion of the washer54, whereby it loosely but securely connects the nut52and washer54, while permitting the nut52to rotate freely relative to the washer54.

FIG. 33depicts the preferred embodiment, wherein the collar85underlies an annular inward projection83around its circumference. However, those skilled in the art will appreciate that the skirt68can be forced outward at spaced locations, which underlie a portion of the projection83.

In one embodiment, when the nut-washer assembly99is rotated onto an end of the u-bolt5, the internally threaded nut52engages threads on a end of the u-bolt, whereby the fastener assembly travels axially toward the curved portion16of the u-bolt. Upon further rotation, further axial travel of the nut-washer assembly99is resisted by the surface or surfaces that are being fastened, secured, or sealed. The resistance is at first relatively slight, however, upon further rotation the resistance increases until the nut52and washer54are seated against each other in nested relationship. In this nested relationship, each plateau74will seat uniformly on a corresponding valley122while opposed inclined faces73and116will be slightly separated. In this relationship, the peaks, provided as plateaus74and plateaus118, on the annular surface72and bearing surface84, respectively, ride over each other. As such, the annular surface72slips easily over the bearing surface84on the washer54as the nut52pushes the washer54before it.

Upon further rotation the resistance increases, the peaks ride over each other with greater and greater difficulty as the load increases. The resistance increases with greater and greater effect by the interlocking effect of the faces73on the nut52and the faces116on the washer54. Eventually, they can slip past each other only when the flange sections102on the washer54begin to resiliently flex. As the nut turns, axial pressure builds, and as this pressure builds, the flange sections102begin to flex.

The flange sections102are designed to resiliently flex through an axial distance which is slightly greater than the clearance between the threads on u-bolt5and the threads on the nut52. Because the flange sections102are able to flex slightly more than this clearance, the washer54can move axially under load to some degree without degradation of the lock between washer54and nut52. At the same time, because the height of the plateau118above the valley122in the washer body82is slightly greater than the clearance also, once a locking relationship is established with the proper preload the nut52and washer54can move slightly relative to each other without loosening the nut-washer assembly99.

The flexing of the flange sections102creates a resilient force tending to keep the faces73on the nut52and the faces116washer54in an interlocked relationship. In this locked relationship, a constant bearing load is resiliently maintained and the peaks of the nut52and washer54are seated generally flush against corresponding valleys122and valleys75, respectively. Also, the faces73seat generally flush against the faces116and prevent the nut-washer assembly99from backing off. In particular, the leading faces73seat against trailing faces116.

Moreover, because the faces73and faces116are preferably provided so as to be complementarily spherically convex and spherically concave, respectively, and all their radii of curvature axially of the nut-washer assembly99and from its axis equal those of the aforementioned valleys122, locking surface contact is maintained between them even if the nut52and washer54are not precisely parallel to each other because the nut does not thread perfectly square onto a end of the u-bolt.

When a predetermined torque setting is reached in turning the nut52of the nut-washer assembly99onto a end of the u-bolt5, the nut-washer assembly99can then be relied upon to resist all axial forces tending to cause the nut52to back off. Increased axial load merely causes the nut52and washer54to become more securely locked together. Only by applying loosening torque to the nut52again, as with a hex wrench, can the fastener assembly150be removed.

Referring now toFIG. 40the shaft10is provided with an axis123, a first shaft element124, and a second shaft element125. The first shaft element124includes a first outer surface126and a radius127. The radius127extends from the axis123of the shaft10to the first outer surface126. The second shaft element128is provided with a locking thread41that includes a root surface45. The distance between the axis123and the root surface45of the second shaft element128is greater than the radius127of the first shaft element124.