Technical field of the invention
The present invention relates to a fastening system and more particularly to a self-locking non-protruding fastening system that consists of bolts and conical or tapered nuts for clamping two or more parts together.
Background of the invention
Generally, nuts and bolts are convenient to use for fastening two or more parts in many industries such as automotive, aerospace and construction etc. In automotive industry, especially suspension parts are secured to a chassis frame of multi-axle vehicles through brackets which are fastened into the chassis frame with the help of fasteners such as nuts and bolts. These nuts and bolts are normally subjected to sever dynamic loads, i.e. sever fatigue loads and sever vibration loads, which therefore leads to frequently loosening of the fasteners in the lifetime of vehicle loads and operations.
FIGS. 1A and IB illustrate a schematic view of a conventional nut and bolt arrangement used in a conventional tandem non-reactive rear suspension (1) and its brackets (2) used in a multi-axle heavy truck vehicle, in accordance with a prior art. In general, the suspension bracket (2) is made of casting process. The strength of the casting bracket (2) is more or less equal strength of the frame material. However, it is far less than the fasteners (usually nuts and bolts) used to clamp the brackets (2) with a chassis frame (3). In conventional bolt and nut fastening arrangement, the nut is usually protrude (i.e., extends beyond the surface of the parts) above the surface of the brackets (2). When clamping the plurality of parts through the brackets (2), the bolt is

inserted into a hole provided in the chassis frame (3) and the brackets (2). Then, the nut is placed on the upper or outer surface of the brackets (2) and positioned in line to the hole axis and simultaneously the bolt is inserted and rotationally tightened on the nut. After tightening the bolt and nut fastening system, the nut along with few threads of the bolt are protruded above the outer surface of the brackets (2).
[004] Since the nut is protruded in the conventional fastening system, this fastening system limits the design modification in the suspension bracket (2) and the parts mounted on or near to the suspension bracket (2) such as leaf spring (4), fuel tank etc. In particular, the protruded nut clashes with the nearby mounted parts in the suspension system of the vehicle. Similarly, the fuel tank and battery carrier brackets of the truck vehicle are heavy frictional contact and impact with the nut in these conventional bolt and nut fastening systems.
[005] Many self-locking fastening systems (such as huck fastener, nylock nut, AMPT nut, etc.,) are also being widely used in the automotive industry. The self-locking nut may solve the loosening issues in the existing bolt and nut fastening system; however, these self-locking nut along with the washer is protruded above the surface of the brackets/parts, which is still have a drawback of frictional contact and load impact on the self-locking nut.
[006] In order to overcome the above disadvantages and drawbacks, one of the conventional aspect of a screw and threaded bracket fastening arrangement is implemented. It consists of a conventional screw (5) and a bracket (2) in which thread is provided in place of hole provided in the conventional bolt and nut joint fastening system. More clearly, the screw (5) is screwed with the threads of the bracket (2), where such arrangement is usually used in an engine, i.e. a cylinder head is clamped with a cylinder black using such screw and bracket arrangement.

[007] FIGS. 2A and 2B illustrate a schematic view of a fastening system having a threaded bolt and a threaded suspension bracket used in the multi-axle heavy truck, in accordance with a prior art. In such arrangement, the suspension spring bracket (2) is provided with internal threads that prone to fail due to entire load to be withstand on the bracket (2), since the yield strength of the bracket (2) is far less than the screw (5) used in the fastening system, as shown in FIGS. 3A and 3B, which illustrate a detailed view of the fastening system having the threaded bolt and the threaded suspension bracket used in the multi-axle heavy truck, in accordance with a prior art. In the conventional bolt nut arrangement, the few threads of the bolt are only subjected to major dynamic load and the remaining threads in the bolt withstand the remaining load, whereas in the screw and bracket arrangement, as the bracket (2) is usually made of casting process the internal threads of the bracket cannot withstand the entire major load, which leads to the joint prone to loosening the screw (5) in the bracket (2).
[008] With respect to the conventional fastening system, it is very difficult to prevent bolt loosening due to severe dynamic load and also frictional contact and load impact of the nearby mounted parts due to protruding of the nut on the surface of the bracket. Hence, there is a need in that art to provide a solution to address all the above mentioned problems observed in the automotive and construction industries. It is essentially required a new fastening system and the present invention provides a unique, simple, highly reliable, low cost, bolt and nut fastening arrangement system. The present invention is more desirable to install and dismantle easily.
Objectives of the invention
[009] A main objective of the present invention is to provide a self-locking non-protruding fastening system, which is capable of achieving self-locking, and preventing bolt and nut loosening and protruding of nut from the surface of brackets.

[010] Another objective of the present invention is to provide a self-locking non-protruding fastening system, which is capable of providing high fatigue strength to withstand severe dynamic load.
[011] Another objective of the present invention is to provide a self-locking non-protruding fastening system, which can be easily installed, dismantled and replaced with conventional bolt and nut fastening system.
[012] Another objective of the present invention is to provide a self-locking non-protruding fastening system, which is simple, light-weight, cost-effective and easy to manufacture.
Summary of the invention
[013] The following summary is provided to facilitate an understanding of some of the innovative features unique to the disclosed embodiments and is not intended to be a full description. A full appreciation of the various aspects of the embodiments disclosed herein can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
[014] According to the present invention, two embodiments of a self-locking non-protruding fastening system are provided and specially designed for preventing loosening of the bolt and nut. These self-locking non-protruding fastening system are especially designed and applicable for automotive, aerospace, construction industries, etc.

[015] According to the first embodiment of the present invention to achieve the above objectives, a self-locking non-protruding fastening system comprises a bracket member having a tapered cavity formed on its bolt hole and being clamped with a frame for mounting a plurality of parts within it. A bolt-like fastening element has a head and an elongated body that is threaded on its outer circumference. A nut-like fastening element has a tapered body provided with an internally threaded aperture on its center. The tapered nut-like fastening element is aligned and placed within one side of the tapered cavity of the bracket member such that the bolt-like fastening element is rotationally tightened into the threaded aperture of the tapered nut-like fastening element at opposing side of the tapered cavity of the bracket member through the frame, which simultaneously expands the tapered region of the nut-like fastening element to be tightly held against the tapered surface of the bracket member cavity. Thus, the self-locking non-protruding fastening system can prevent the loosening of nut from the bolt even severe vibration loads and severe dynamic loads acted on the fastening system.
[016] The tapered nut (conical shape nut/conical nut) is provided with an internal thread, where as the conical shape cavity is provided in the bracket to accommodate the tapered nut. During assembling, the tapered nut is placed in the conical shape cavity in the bracket. Then, the bolt is rotationally tightened such that the bolt pulls the tapered nut and held the parts to be clamp together. Upon further tightening process, the materials around the cavity is expanded and tightly held the tapered nut. A compression force is experienced on the tapered nut due to slight expansion of the bracket which is around the surface of the tapered portion. Thereby, the nut is self-locked to prevent the loosening of the nut from the bolt. Also, it completely limits the protruding of the tapered nut from the surface of the parts.

[017] The tapered nut-like fastening element is grinded to be smoothened on the outer surface of the tapered body, whereas the bracket is grinded to be smoothened on the inner surface of the tapered cavity. The tapered nut-like fastening element is completely housed within the tapered cavity of the bracket so that the tapered outer surface of the nut-like fastening element is held against the tapered inner surface of the bracket cavity. The tapered nut-like fastening element is made by an internal thread rolling process with steel materials of low carbon steel, medium carbon steel and alloy steel. The threaded aperture at the enlarged region of the tapered nut is formed with a hexagonal or square slot at its upper side to hold and place the tapered nut inside the tapered cavity of the bracket member.
[018] According to the second embodiment of the present invention to achieve the above objectives, a self-locking non-protruding fastening system comprises a bracket member having a tapered cavity hexagonally shaped on its inner top surface, and being clamped with a frame for mounting a plurality of parts within it. A bolt-like fastening element has a head and an elongated body that is threaded on its outer circumference. A nut-like fastening element has a tapered body provided with a hexagonal head region on its external surface and an internally threaded aperture on its centre. The tapered nut-like fastening element is aligned and placed within one side of the tapered hexagonal cavity of the bracket member such that the bolt-like fastening element is rotationally tightened into the threaded aperture of the tapered nut-like fastening element at opposing side of the tapered hexagonal cavity of the bracket member through the frame, which simultaneously expands the tapered region of the nut-like fastening element to be tightly held against the tapered hexagonal surface of the bracket member cavity.
[019] The tapered hexagonal nut is provided with an internal thread, whereas the conical-hexagonal shaped cavity is provided in the bracket to accommodate the

tapered hexagonal nut. During assembling, the tapered hexagonal nut is placed in the tapered hexagonal shape cavity in the bracket. Then, the bolt is rotationally tightened such that the bolt pulls the tapered hexagonal nut and held the parts to be clamp together. Upon further tightening process, the materials around the cavity is expanded and tightly held the tapered hexagonal nut. A compression force is experienced on the nut due to slight expansion of the bracket which is around the surface of the tapered portion. Thereby, the hexagonal portion of the nut is self-locked to prevent the nut rotation at the beginning of tightening process, and prevent the loosening of the nut from the bolt. Also, it completely limits the protruding of the tapered hexagonal nut from the surface of the parts.
[020] The tapered hexagonal nut-like fastening element is grinded to be smoothened on the outer surface of the tapered body and the hexagonal head region for resisting rotational movement of the nut-like fastening element while tightening the bolt-like fastening element. The bracket is grinded to be smoothened on the inner surface of the tapered hexagonal cavity. The tapered hexagonal nut-like fastening element is completely housed within the tapered hexagonal cavity of the bracket so that the tapered outer surface of the nut-like fastening element is held against the tapered inner surface of the bracket cavity. The tapered hexagonal nut-like fastening element is made by an internal thread rolling process with steel materials of low carbon steel, medium carbon steel and alloy steel. The self-locking non-protruding fastening system of both the first and second embodiments is used in a suspension system of a multi-axle heavy vehicle for clamping the bracket member into a vehicle chassis frame.
Brief description of the accompanying drawings

[021] These and other objects, features and advantages of the present invention will be further apparent from the following description taken in conjunction with the several figures of the accompanying drawings which show, only by way of example of this present invention. For a better understanding of the present inventions, reference is made to the following detailed description of the embodiments considered in accordance with the accompanying drawings in greater detail.
[022] FIGS. 1A and 1B illustrate a schematic view of a conventional nut and bolt arrangement used in a conventional tandem non-reactive rear suspension and its brackets used in a multi-axle heavy truck, in accordance with a prior art;
[023] FIG. 2A and 2B illustrate a schematic view of a fastening system having a threaded bolt and a threaded suspension bracket used in the multi-axle heavy truck, in accordance with a prior art;
[024] FIGS. 3A and 3B illustrate a detailed view of the fastening system having the threaded bolt and the threaded suspension bracket used in the multi-axle heavy truck, in accordance with a prior art;
[025] FIG. 4 illustrates a schematic assembled view of a self-locking non-protruding fastening system, in accordance with an exemplary first embodiment of the present invention;
[026] FIGS. 5A and 5B illustrate a detailed exploded view of the self-locking non-protruding fastening system, in accordance with an exemplary first embodiment of the present invention;

[027] FIGS. 6A and 6B respectively illustrate front and rear views of a bracket in the self-locking non-protruding fastening system, in accordance with an exemplary first embodiment of the present invention;
[028] FIG. 6C illustrates an isometric view of a tapered nut in the self-locking non-protruding fastening system, in accordance with an exemplary first embodiment of the present invention;
[029] FIG. 7 illustrates a sectional view of a joint position of the self-locking non-protruding fastening system, in accordance with an exemplary first embodiment of the present invention;
[030] FIG. 8 illustrates a schematic assembled view of a self-locking non-protruding fastening system, in accordance with an exemplary second embodiment of the present invention;
[031] FIG. 9 illustrates a detailed exploded view of the self-locking non-protruding fastening system, in accordance with an exemplary second embodiment of the present invention;
[032] FIG. 10A illustrates a detailed view of a bracket in the self-locking non-protruding fastening system, in accordance with an exemplary second embodiment of the present invention;
[033] FIG. 10B illustrates an isometric view of a tapered hexagonal nut in the self-locking non-protruding fastening system, in accordance with an exemplary second embodiment of the present invention; and

[034] FIG. 11 illustrates a sectional view of a joint position of the self-locking non-protruding fastening system, in accordance with an exemplary second embodiment of the present invention.
[[035] FIG. 12 illustrates an isometric view of a tapered nut with three circular slots in the self-locking non-protruding fastening system,
Detailed description of the preferred embodiment of the invention
[036] The following description is of exemplary embodiment of the invention only, and is not the limited scope, applicability or configuration of the invention. Rather, the following description is intended to provide a convenient illustration for implementing various embodiments of the invention. As will become apparent, various changes may be made in the function and arrangement of the structural/operational features described in these embodiments without departing from the scope of the invention as set forth herein. It should be appreciated that the description herein may be adapted to be employed with alternatively configured devices having different shapes, components, and the like and still fall within the scope of the present invention. Thus, the detailed description herein is presented for the purposes of illustration only and not of limitation.
[037] The present invention will be described based on the illustrated examples as shown below. The present embodiment will be described, herein below, paragraphs by referring the accompanying drawings. A self-locking non-protruding fastening system of different embodiments is described herein. The self-locking non-protruding fastening system of the present invention is described in the figures with the example

of application in multi-axle vehicles in automotive industry only for the purpose of easy understanding but not by the way of any limitations, where these fastening system can also be applicable in any other industries such as aerospace and construction, etc.
[038] FIG. 4 illustrates a schematic assembled view of a self-locking non-protruding fastening system (15), in accordance with an exemplary first embodiment of the present invention. The self-locking non-protruding fastening system (15) is used for clamping a bracket or bracket member (12) of a suspension system into a structural mounting frame or chassis frame (3) of a multi-axle heavy vehicle. The suspension bracket (12) is adapted to clamp and mount multiple parts of the vehicle in it, where the multi-axle heavy vehicle is provided with a plurality of brackets (12) to mount several vehicle parts such as leaf spring, fuel tank, etc. The self-locking non-protruding fastening system (15) is primarily composed of a bracket member (12), a bolt-like fastening element (7) and a tapered nut-like fastening element (6). The bracket member (12), the bolt-like fastening element (7) and the nut-like fastening element (6) can be respectively referred as bracket, bolt and nut throughout all the embodiments described in the specification only for the purpose of clear understanding of the present invention but not by the way of any limitations.
[039] The tapered nut (6) threadedly mates with the bolt (7) for fastening two or more parts, joints etc. In the first embodiment of the present invention, the bolt (7) referred herein is a conventional bolt having external thread, in particular the bolt (7) is composed of a head (7a) and an elongated body (7b) that is threaded on its outer circumference. The nut (6) is uniquely and innovatively designed as a taper shape nut (6), in particular the nut (6) is composed of a tapered body (6a) provided with an internally threaded aperture (17) on its center, as shown in FIGS. 5A and 5B, which illustrate a detailed exploded view of the self-locking non-protruding fastening

system, in accordance with an exemplary first embodiment of the present invention. The bolt (7) is a commonly used bolt type; therefore, it is not discussed much hereafter in the description. Whereas the nut (7) as well as part of the bracket are specially designed all the embodiments of the present invention to prevent the bolt and nut loosening and not-protruding from the joints, which is easy of manufacturing, easy of dismantling, low cost and light-weight.
[040] FIGS. 6A and 6B respectively illustrate front and rear views of the bracket (12) in the self-locking non-protruding fastening system (15), in accordance with an exemplary first embodiment of the present invention. In general, the bracket (12) is made of casting and having a tapered or conical cavity (8) (also referred as a taper shape chamfer) therethrough, where this tapered cavity (8) is provided in a bolt hole of the bracket (12) to receive the threaded elongated body (7b) of the bolt (7). The bracket (12) is usually composed of several tapered or conical cavities (8) through which several bolts (7) and tapered nuts (6) are respectively inserted and tightened for fastening and clamping the bracket (12) into any structural mounting frame or chassis frame (3), as clearly shown in figures 6A and 6B. More clearly, the tapered cavity (8) of the bracket (12) is specially designed as an enlarge and beveled rim of bolt hole (i.e.an internal conical form hole or funnel-shaped cavity) to accommodate or house the tapered nut (6) within it, so that the tapered or conical nut (6) can be completely inserted and housed within the tapered or conical cavity (8) of the bracket (12) so that the tapered outer surface of the nut (6) is held against the tapered inner surface of the bracket cavity (8). The bracket (12) is grinded to be smoothened on the inner surface of the tapered cavity (8).
[041] FIG. 6C illustrates an isometric view of the tapered nut (6) in the self-locking non-protruding fastening system (15), in accordance with an exemplary first embodiment of the present invention. The threaded or conical nut (6) is composed of

a tapered body (6a) provided with an internally threaded aperture (17) on its center. The upper side of the threaded aperture (17) at the enlarged region of the tapered nut (6) is formed with a hexagonal or square slot (20) in order to hold initially (to avoid slipping) and to assist for easy assembling of the tapered nut into the conical cavity of the bracket, which eases and minimizes the assembly time. The tapered nut (6) is grinded to be smoothened on the outer surface of the tapered body (6a). The tapered nut (6) is made by an internal thread rolling process with steel materials such as low carbon steel, medium carbon steel and alloy steel in any property class such as 5, 6, 7, 8, 9, 10 and 12.
[042] FIG. 7 illustrates a sectional view of a joint position of the self-locking non-protruding fastening system, in accordance with an exemplary first embodiment of the present invention. The externally taper-shaped nut (6) has pre-taped internal threads in its aperture (17) that match with the threads in the elongated body (7b) of the bolt (7) to threadedly engage the bolt (7) and the nut (6) together during assembling. In the present embodiment, the tapered nut (6) can be characterized by any property class such as 5, 6, 7, 8, 9, 10 and 12. Since weight reduction and cost saving are important in automotive industry, accordingly the present self-locking non-protruding fastening system provides cost saving compared to the conventional joint by means of approximate reduction in the nut weight compared to the conventional nut. In addition, the length of the bolt is also limited to the surface of the joint, which therefore reduces the length of the bolt, and thereby weight and cost of the present self-locking non-protruding fastening system is less than the conventional bolt and nut fastening system, i.e. the present fastening system is simple, light-weight, cost-effective and easy to manufacture.
[043] During assembly, the tapered nut (6) is inserted and placed within the internal conical cavity (8) formed in upper front side of the bolt hole of the bracket (12). Then,

the elongated body (7b) of the bolt (7) is inserted at rear side (opposite side of the conical cavity) of the bolt hole of the bracket (12) through the mounting frame (3) and is rotationally tightened into the threaded aperture (17) of the tapered nut (6) at the tapered cavity (8) of the bracket member (12). In particular, the elongated body (7b) of the bolt (7) is inserted into a through-hole formed in the frame (3) at its one side (rear side) and further inserted into the tapered cavity (8) at the rear side of the bracket (12) that is positioned and aligned with the through-hole at other side (front side) of the frame (3). Then, the bolt (7) is finally threaded into the tapered nut (6) placed inside the top region of the tapered cavity (8) of the bracket (12). Simultaneously, the bolt (7) is tightened to pull the tapered nut (6) in such a way that the tapered nut (6) is properly seated in the conical shape cavity (8) (i.e. internal taper) of the bracket (12). Upon continuous pulling of the tapered nut (6) by bolt (7), the material of the bracket (12) around the tapered nut (6) is slightly expanded to lock the tapered nut (6) within the conical cavity (8) of the bracket (12).
[044] In addition, a compression force is experienced on the tapered nut (6), and thereby, the tapered nut (6) is tightly held within the conical cavity (8) by the bracket (12) along with the pulling force of the bolt (7). Upon further tightening until the head (7a) of the bolt (7) rested on the surface of the frame (3), the threads of bolt (7) and nut (6) are mated together with one another, which makes the tail end of the bolt and nut in line with the surface of the bracket (12) in order to achieve a non-protruding feature of the present fastening system. Once completely tightened, the tapered nut (6) is restricted to move in the transverse direction relative to an axis of the bolt (7), which achieves a self-locking feature of the present fastening system. As a result, a consistent contact between the tapered surface of the tapered nut (6) and the tapered surface of the tapered cavity (8) of the bracket (12) is achieved, i.e. the shape of the tapered nut (6) is conformed to the tapered surface of the conical cavity (8) of the bracket (12). Thereby, such self-locking non-protruding fastening system can prevent

loosening of the tapered nut (6) from the bolt (7) even in case of severe vibration loads and severe dynamic loads applied on the fastening joint due to its high fatigue strength. In general since the transverse vibration is a main cause of bolt and nut loosening, however in the present invention, the tapered nut (6) is tightly held within the conical cavity by the bracket (12), which completely arrests and prevents the movement of the tapered nut (6) in the transverse direction relative to the bolt (7). Thus, such self-locking non-protruding fastening system is easy to assemble, dismantle and replace with the conventional bolt and nut fastening system.
[045] FIG.8 illustrates a schematic assembled view of a self-locking non-protruding fastening system (16), in accordance to an exemplary second embodiment of the present invention. The self-locking non-protruding fastening system (16) is used for clamping a bracket member (13) of a suspension system into a structural mounting frame or chassis frame (3). According to the second embodiment of the present invention, the self-locking non-protruding fastening system (16) is primarily composed of a bracket member (13), a bolt-like fastening element (10) and a tapered hexagonal nut-like fastening element (9). The bracket member (13), the bolt-like fastening element (10) and the nut-like fastening element (9) can be respectively referred as bracket, bolt and tapered or hexagonal nut throughout the embodiment described in the specification only for the purpose of clear understanding of the present invention but not by the way of any limitations.
[046] The tapered hexagonal nut (9) threadedly mates with the bolt (10) for fastening two or more parts, joints, etc. In the second embodiment of the present invention, the bolt (10) referred herein is a conventional bolts having external thread, in particular the bolt (10) is composed of a head (10a) and an elongated body (10b) that is threaded on its outer circumference. The nut (9) is uniquely and innovatively designed as a tapered hexagonal nut (i.e. taper shape in lower end with a hexagonal shape in top end

at the outer side of the nut), where this tapered hexagonal nut (9) is formed with a tapered hexagonal body (9a) provided with an internally threaded aperture (18) on its center, as shown in FIG. 9, which illustrates a detailed exploded view of the self-locking non-protruding fastening system, in accordance with an exemplary second embodiment of the present invention. Since the bolt (10) is a commonly used bolt type, therefore, it is not discussed much hereafter in the description. Whereas, the nut (9) as well as part of the bracket (13) are specially designed in the present embodiment to prevent the bolt and nut loosening and not-protruding from the fastening joints, which is easy of manufacturing, easy of dismantling, low cost and light-weight.
[047] FIG. 10A illustrates a detailed view of a bracket (13) in the self-locking non-protruding fastening system, in accordance with an exemplary second embodiment of the present invention. In general, the bracket (13) is made of casting and having a tapered hexagonal cavity (11), i.e. the partly tapered cavity (11) is hexagonally shaped on its inner top surface, where this tapered hexagonal cavity (11) is provided in the bolt hole of the bracket (13). The bracket (13) is usually composed of several tapered hexagonal cavities (11) through which several bolts (10) and tapered hexagonal nuts (9) are respectively inserted and tightened for fastening and clamping the bracket (13) into any structural mounting frame or chassis frame (3), as clearly shown in figure 10A.
[048] More clearly, the tapered hexagonal cavity (11) of the bracket (13) is specially designed as an enlarge and beveled rim of bolt hole (i.e. an internal conical form hole or funnel-shaped cavity) with a hexagonal shape externally at top end to accommodate the tapered hexagonal nut (9) within it, so that the tapered hexagonal nut (9) can be completely inserted and housed within the tapered hexagonal cavity (11) of the bracket (13) so that the tapered and hexagonal outer surface of the nut (9)

is held against the tapered and hexagonal inner surface of the bracket cavity (11). The bracket (13) is grinded to be smoothened on the inner surface of the tapered hexagonal cavity (11). The threaded hexagonal nut (9) is composed of a tapered body (9a) provided with a hexagonal head region (19) on its external surface and an internally threaded aperture (18) on its center, which is clearly shown in FIG. 10B, which illustrates an isometric view of a tapered hexagonal nut (9) in the self-locking non-protruding fastening system (16), in accordance with an exemplary second embodiment of the present invention. The tapered hexagonal nut (9) is grinded to be smoothened on the outer surface of the tapered body (9a) and the hexagonal head region (19) for resisting rotational movement of the nut (9) while tightening the bolt (10). The tapered hexagonal nut (9) is made by an internal thread rolling process with steel materials such as low carbon steel, medium carbon steel and alloy steel in any property class such as 5, 6, 7, 8, 9, 10 and 12.
[049] FIG. 11 illustrates a sectional view of a joint position of the self-locking non-protruding fastening system, in accordance with an exemplary second embodiment of the present invention. The externally taper-hexagonal-shaped nut (9) has pre-taped internal threads on its aperture (18) that match with the threads in the elongated body (10b) of the bolt (10) to threadedly engage the bolt (10) and the nut (9) together during assembling. In the present embodiment, the tapered hexagonal nut (9) can be characterized by any property class such as 5, 6, 7, 8, 9, 10 and 12. The present self-locking non-protruding fastening system (16) provides cost saving compared to the conventional joint by means of approximate reduction in the nut weight compared to the conventional nut. In addition, the length of the bolt is also limited to the surface of the joint, which therefore reduces the length of the bolt, and thereby weight and cost of the present self-locking non-protruding fastening system is less than the conventional bolt and nut fastening system, i.e. the present fastening system is simple, light-weight, cost-effective and easy to manufacture.

[050] During assembly, the tapered hexagonal nut (9) is inserted and placed within the inside of the tapered hexagonal cavity (chamfer) (11) formed in upper front side of the bolt hole of the bracket (13). Then, the elongated body (10b) of the bolt (10) is inserted at rear side (opposite side of the tapered hexagonal cavity) of the bolt hole of the bracket (13) through the mounting frame (3) and is rotationally tightened into the threaded aperture (18) of the tapered hexagonal nut (9) kept at the tapered hexagonal cavity (11) of the bracket member (13). In particular, the elongated body (10b) of the bolt (10) is inserted into a through-hole formed in the frame (3) at its one side (rear side) and further inserted into the tapered hexagonal cavity (11) at the rear side of the bracket (13) that is positioned and aligned with the through-hole at other side (front side) of the frame (3). Then, the bolt (10) is finally threaded into the tapered hexagonal nut (9) placed inside the top region of the tapered hexagonal cavity (11) of the bracket (13). Simultaneously, the bolt (10) is tightened to pull the tapered hexagonal nut (9) in such a way that the tapered hexagonal nut (9) is properly seated in the internal taper-hexagoanal-shaped cavity (11) of the bracket (13). Due to continuous pulling of the tapered hexagonal nut (9) by bolt (10), the material of the bracket (13) around the tapered hexagonal nut (9) is slightly expanded to lock the tapered hexagonal nut (9) within the tapered hexagonal cavity (11) of the bracket (13).
[051] In addition, a compression force is experienced at the conical shape of the bracket (13), and thereby, the tapered hexagonal nut (9) is tightly held within the tapered hexagonal cavity (11) by the bracket (13) along with the pulling force of the bolt (10). Upon further tightening until the head (10a) of the bolt (10) arrested on the surface of the frame (3), the threads of bolt (10) and nut (9) are mated together with one another, which makes the tail end of the bold and nut in line with the surface of the bracket (13) in order to achieve a non-protruding feature of the present fastening system. In addition, the hexagonal portion (19) provided in the tapered hexagonal nut

(9) is properly seated and secured inside the hexagonal cavity (11) provided in the bracket (13). Once completely tightened, the tapered hexagonal nut (9) is restricted to move in the transverse direction relative to an axis of the bolt (10), which ahiceves a self-locking feature of the present fastening system. As a result, a consistent contact between the tapered and hexagonal surfaces of the tapered hexagonal nut (9) and the tapered and hexagonal surfaces of the tapered hexagonal cavity (11) of the bracket (13) is achieved, i.e. the shape of the tapered hexagonal nut (9) is conformed to the tapered hexagonal surface of the cavity (11) in the bracket (13). Thereby, such self-locking non-protruding fastening system can prevent loosening of the tapered hexagonal nut (9) from the bolt (10) even in case of severe vibration loads and severe dynamic loads acted on the fastening joint, i.e. withstanding severe load due to its high fatigue strenght. In general since the transverse vibration is a main cause of bolt and nut loosening, however in the present invention, the tapered hexagonal nut (9) is tightly held within the tapered hexagonal cavity (11) by the bracket (13), which completely arrests and prevents the movement of the tapered hexagonal nut (9) in the transverse direction relative to the bolt (10). As a result, the present self-locking non-protruding fastening system (16) prevents vibration induced loosening of the tapered hexagonal nut (9).
[052] To summarize, the self-locking non-protruding fastener (15, 16) in accordance with the first and second embodiments of the present invention, have various beneficial features. For example, the fastening systems (15, 16) have self-locking feature (which prevent vibration resistance) and non-protruding on the surface of the bracket. Also, it is a low cost and light-weight fastener system and requires less maintenance.
[053] Many modifications and other embodiments of the invention (for example, providing a tapered nut with three circular slots (21, Fig.12) instead of providing a

tapered nut (6) with a hexagonal or square slot (20, Fig.6C)) in the self-locking non-protruding fastening system may come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. In addition, some changes such as tapered square nut instead of tapered hexagonal nut, stepped conical shaped nut etc. may be made to these specific embodiments, and such modifications are contemplated by the principle of the present invention. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.

We Claim:
1. A self-locking non-protruding fastening system (15), comprising:
a bracket member (12) having a tapered cavity (8) formed on its bolt hole and being clamped with a frame for mounting a plurality of parts within it;
at least one bolt-like fastening element (7) having a head and an elongated body that is threaded on its outer circumference; and
at least one nut-like fastening element (6) having a tapered body provided with an internally threaded aperture on its center,
wherein the tapered nut-like fastening element (6) is aligned and placed within one side of the tapered cavity of the bracket member (12) such that the bolt-like fastening element (7) is rotationally tightened into the threaded aperture of the tapered nut-like fastening element (6) at opposing side of the tapered cavity of the bracket member (12) through the frame, which simultaneously expands the tapered region of the nut-like fastening element (6) to be tightly held against the tapered surface of the bracket member cavity.
2. The fastening system (15) as claimed in claim 1, wherein the tapered nut-like fastening element (6) is grinded to be smoothened on the outer surface of the tapered body.
3. The fastening system (15) as claimed in claim 1, wherein the bracket (12) is grinded to be smoothened on the inner surface of the tapered cavity (8).
4. The fastening system (15) as claimed in claim 1, wherein the tapered nut-like fastening element (6) is completely housed within the tapered cavity (8) of the bracket (12) so that the tapered outer surface of the nut-like fastening element (6) is held against the tapered inner surface of the bracket cavity (8).

5. The fastening system (15) as claimed in claim 1, wherein the tapered nut-like fastening element (6) is made by an internal thread rolling process with steel materials such as low carbon steel, medium carbon steel, high carbon steeland alloy steel.
6. The fastening system (15) as claimed in claim 1, wherein the threaded aperture at the enlarged region of the tapered nut is formed with a hexagonal or square slot (20) or tapered nut with three circular slots (21)at its upper side to hold and place the tapered nut inside the tapered cavity of the bracket member.
7. A self- locking non-protruding fastening system (16), comprising:
a bracket member (13) having a tapered cavity (11) hexagonally shaped on its inner top surface, and being clamped with a frame for mounting a plurality of parts within it;
at least one bolt-like fastening element (10) having a head and an elongated body that is threaded on its outer circumference; and
at least one nut-like fastening element (9) having a tapered body provided with a hexagonal head region on its external surface and an internally threaded aperture on its centre,
wherein the tapered nut-like fastening element (9) is aligned and placed within one side of the tapered hexagonal cavity (11) of the bracket member (13) such that the bolt-like fastening element (10) is rotationally tightened into the threaded aperture of the tapered nut-like fastening element (9) at opposing side of the tapered hexagonal cavity (11) of the bracket member (13) through the frame, which simultaneously expands the tapered region of the nut-like fastening element (9) to be tightly held against the tapered hexagonal surface of the bracket member cavity (11).

8. The fastening system (16) as claimed in claim 7, wherein the tapered hexagonal nut-like fastening element (9) is grinded to be smoothened on the outer surface of the tapered body and the hexagonal head region (19) for resisting rotational movement of the nut-like fastening element (9) while tightening the bolt-like fastening element (10).
9. The fastening system (16) as claimed in claim 7, wherein the bracket (13) is grinded to be smoothened on the inner surface of the tapered hexagonal cavity (11).
10. The fastening system (16) as claimed in claim 7, wherein the tapered hexagonal nut-like fastening element (9) is completely housed within the tapered hexagonal cavity (11) of the bracket (13) so that the tapered outer surface of the nut-like fastening element (9) is held against the tapered inner surface of the bracket cavity (8).
11. The fastening system (16) as claimed in claim 7, wherein the tapered hexagonal nut-like fastening element (9) is made by an internal thread rolling process with steel materials such as low carbon steel, medium carbon steel, high carbon steel and alloy steel.
12. The fastening system as claimed in any of the preceding claims 1-6 or 7-11, wherein the self-locking non-protruding fastening system (15, 16) is used in a suspension system of a multi-axle heavy vehicle for clamping the bracket member (12) into a vehicle chassis frame.