FIELD OF INVENTION
The present invention relates to a Hex Lobular - Hex Flange screw. It is a unique screw having hex lobular external driven head and a hex shape load-bearing flange, providing a unique feature of tightening and loosening the screw using any of the above-mentioned two features based on the application. In practice, the OEM's use the hex lobular driven head with a costlier Socket drive whereas the Service Industry uses the hex shape driven flange with a low cost Hex Spanner drive. The Hex load bearing flange finds it's use in critical post assembly tightening or loosening of the fastener for minor corrections, since the hex lobular driven head may be hidden or not reachable after assembly for minor corrections. The other uniqueness of this invention is that the material wastage in forging this part is not more than the existing Hex lobular circular flange screw. This special unique low cost screw with combination of two driven features provides the user to select the drive based on the application and the pros and cons of each feature.
BACKGROUND OF THE INVENTION
Fasteners are used to join more than two members. The tightening torque applied to the fastener is converted into axial load in the joint. To transmit the torque a driven feature is required on the fastener. The driven gets torque by a mating part through which is torque transmitted by hand or powered motor. A dial or digital indicator to indicate the amount of torque applied is coupled with this arrangement.
There are two driven features widely used in the field namely Hex lobular and Hexagon driven head. In case of Hex lobular driven head, the torque is transmitted through a socket tool drive, which is made of chrome vanadium steel to give optimum life. In case of Hexagon driven head, the torque is transmitted through a hexagonal spanner (Closed box or open type)
A two-point contact is obtained as the hexagon is held on its flats or edges. A dosed box spanner is also used to drive it, which has a six-point contact. The box spanners have an advantage over spanners with a six-point contact and are also easy to manufacture.

Hexalobular feature is a hexagon with its corners radiused. In this case, there is a surface contact between the driven part feature and the drive socket during torque transmission.
The other important factor about the Hexalobular driven is that the socket life is very high The socket tool and the driven both have radiused edges, which have a surface contact and hence load is evenly distributed on the radiused surface of the socket. But the tool cost is very high compared to that of a hexagon box spanner, as it is difficult to manufacture. OEM's or Original Equipment manufacturers prefer Hexalobular feature in spite of high tool cost due to
a. High efficiency in transmitting torque
b. High socket Tool life
c. No damage of the corners of the part after assembly.
d. Loosening is as easy as assembling.
But the service sector prefers the Hexagon feature since the hexagon spanner drive cost is much lower. Hexalobular and hexagon driven features used in engine application often have an angular flange or a flat collar. Flat Collar or angular flange being an integrated system is used in place of a washer to increase the load bearing capacity of a bolt.
The Technology behind this invention is cold forging and this unique part configuration is actually achieved by the innovative forging process and tool design using the subject Multi stage transfer type cold forging header. There are no limitations or problems of the cold forging technology whereas the limitation is with respect to the application.
As mentioned above, the limitation addressed in this invention is the regular Hex lobular driven head which needs a costlier Socket drive and the hex lobular driven head poses a limitation of usage during post assembly corrections of the Fastener for tightening or loosening, since the hex lobe may be hidden after assembly and the space may be a constraint for Socket drive.

This invention provides a unique solution to overcome the above-mentioned limitation by the special feature of hex flange which is an additional low cost feature provided in the same screw wherein the hex load bearing flange needs a low cost spanner drive instead of the costlier socket drive and the later finds the application in the critical post assembly corrections of the fastener, thereby overcoming the limitation addressed in the hex lobular driven head feature of the regular hex lobular head screw.
PRIOR ART
During the prior art search, it appears that none of the documents cited completely disclosed the invention of the proposed Patent application (i.e., a bolt with combination of hex lobular driven head and flange with Hex shape). The hits basically did not reveal any document explicitly showing a bolt with such combination.
Furthermore, there is no single bolt having hex lobular external driving head and a load bearing hexagonal flange having multiple provision for tightening or loosening purpose.
In addition, even if we think of combining the earlier mentioned two features to arrive with the single screw, it can be said that a person of average skill in our area of technology cannot arrive at the instant invention.
Some of the reasons for the above justification are listed below:
1. This process innovation in cold forging is unique to achieve the said product by cold forging in a multi-stage transfer type cold forging header
2. The tool design and tools manufacturing needs high skill to execute the subject invention.

OBJECTS OF INVENTION
The primary objective of the invention is to develop a screw having hex lobular driven head and hexagon load bearing flange.
Another objective of the invention is to develop a method of fastening objects comprising utilizing at lease one screw as described above for fastening the objects.
STATEMENT OF INVENTION
Present invention is related to a screw having hex lobular driven head and hexagon load bearing flange and a method of fastening objects comprising utilizing at lease one screw as described above for fastening the objects.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1: illustrates the evolution of a Hex lobular feature in the fastener.
Figure 2: illustrate a typical Hex lobular screw with a circular load-bearing flange (6) and hex lobular driven head (5).
Figure 3: illustrate a typical hex driven head (7) screw with a circular load-bearing flange (8).
Figure 4: illustrate the invention of "Hex Lobular - Hex Flange (H2LF) Screw" with the combined features of Hex Lobular screw and Hexagon head screw.
Figure 5: shows the actual invented product with two different views
DESCRIPTION OF THE INVENTION
The primary embodiment of the invention is a screw having hex lobular driven head and hexagon load bearing flange.
In yet another embodiment of the present invention the head comprises symmetrical and equi-spaced six lobes.

In still another embodiment of the present invention the flange comprises symmetrical and equi-spaced six sides.
In still another embodiment of the present invention the screw is of pre-determined length based on its application.
In still another embodiment of the present invention the hex lobular driven head thickness is equal to the hexagon load-bearing flange.
In still another embodiment of the present invention the hex lobular driven head and the hexagon load-bearing flange have common wrench height.
In still another embodiment of the present invention the screw is manufactured using cold forging technique
In still another embodiment of the present invention a method of fastening objects comprising utilizing at lease one screw as described above for fastening the objects.
This invention relates to the "Hex Lobular - Hex Flange (H2LF) Screw" for any application with dual feature of Hex lobular driven head and Hex load-bearing flange for Fastening.
Fasteners are used to join more than two members. The tightening torque applied to the fastener is converted into axial load in the joint. To transmit the torque, a driven feature is required on the fastener. The driven gets torque by a mating part through which is torque transmitted by hand or powered motor. A dial or digital indicator is coupled with this arrangement to indicate the amount of torque.
Generally, the Hex Lobular configuration on the Fastener head is used as an external driven mechanism with a Socket drive for transmitting the required torque for applying the Clamping load on the joints. The socket tool drive is made of chrome vanadium steel to give optimum life. The OEM's uses this hex lobular driven head normally, but the socket drive tool cost is high when compared to the low cost hex spanner. There is a surface contact between the driven part feature and the drive socket. The hex lobular configuration is more evident from the following drawings in which Figure: 1

illustrates the evolution of a Hex lobular feature in the fastener. In figure 1, figure 1(A) shows a hexagon (1) with corners of the hexagon radiused (2). Figure 1(B) shows tangential radius (3) between the corners of the hexagon radiused (2). Finally figure 1(C) shows hex lobe (4).
Both the socket tool drive and the driven have radiused edges, which have a surface contact and hence load is evenly distributed on the radiused surface of the socket. But the socket tool cost is very high. OEM's or Original Equipment Manufacturers prefer Hex lobular feature in spite of high tool cost due to high efficiency in torque transmission and high socket tool life.
Figure: 2 illustrate a typical Hex lobular screw with a circular load-bearing flange (6) and hex lobular driven head (5). It is clear that the OEM's can afford for such hex lobular driven head configuration and a costlier socket drive rather than the service industries, which requires economical usage of Fasteners by design.
The alternate economical solution for Service industry is a Hex flange screw with a hex shape driven head and a circular load-bearing flange. A hex spanner is used to drive the hexagon driven feature for the required torque. The two-point contact is obtained as the hexagon is held on its flats or edges. This finds a maximum usage in service industries for ease in usage, better economics and for easy corrections in the post assembly stage wherein the hex lobular driven head might be unreachable after post assembly almost all the times.
Figure: 3 illustrate a typical hex driven head (7) screw with a circular load-bearing flange (8). This hex head screw driven feature finds application not only in service industries, but also in consumer products application and home applications wherein the hexagon spanner drive is a low cost option for general usage and it is very much easier to use without any skill.
But the practical problem prevailing in the world for usage of hex lobular head screw and hex head screw is the limitation in application for all fields at any time due to the configuration of the driven head and the economics of the drive tool. The other

limitation addressed is that the advantages of both the screw features are not present in one single screw type, which becomes application limitation by design.
An invention is made to overcome the above-mentioned problem / limitation by combining both the hex lobular and hexagon features as hex lobular driven head and hex load bearing flange in a single screw named as Hex Lobular - Hex Flange (H2LF) Screw.
Figure: 4 illustrate the invention of "Hex Lobular - Hex Flange (H2LF) Screw" with the combined features of Hex Lobular screw and Hexagon head screw. It has Hex lobular Driven Head (9) and Hexagon load bearing flange (10).
The product has hex head thickness equal to its hex lobe counter part and both features have a common wrench height in order to use both the drives for tightening or loosening purpose. This product is manufactured through cold forging process in a multi-stage transfer type cold forging header. The cold forged parts are then thread rolled and heat treated as per the standard procedure to required grade as per the customer requirement and supplied in a fully finished condition to suit assembly requirements.
This invention gives the user the freedom to select any of the drives like Hex lobular socket drive or Hex head spanner drive based on the application. This product will have the hex lobular driven feature for OEM application based on the requirement of efficient torque transmission and high socket drive tool life despite of high tool cost. Normally, the hex lobular driven head will get hidden after assembly, wherein the hexagon load-bearing flange is used as driven with hex spanner drive for minor adjustments during post assembly corrections. The hex flange serves dual purpose as driven feature and load-bearing flange. Also the minimum-bearing diameter is met not disturbing the load triangles. The part is of lesser weight when compared to-a hex flange configuration prescribed in the standards and of almost same weight as that of a Hexalobular part. The material wastage is minimum and there is 90% yield achieved.

The Hex Lobular - Hex Flange (H2LF) Screw comprises symmetrical and equi-spaced six lobes as driven head and symmetrical and equi-spaced six sides of Hexagon.
There is no orientation required between the hex lobular head and the hexagon flange.
The subject invention made is a M8 Screw, which is not a limitation and the concept is applicable for any applicable thread sizes.
The length of the screw can be of any range based on the application.
The Washer face dimensions as per ISO 4017.
This product tested in a Junker type Vibration testing machine lasted for 50,000 cycles without any loss of pre-load.
Tensile testing of this part meets the requirements as per ISO 898 - Part 1
Torque testing of this part meets the requirements as per ISO 16047.
This product manufactured thro' Cold forging technique is applicable to any other feasible processes and machineries.
This can be made use of in bolt application also.
Process parameters
The forging process is designed on a progressive header and the semi-finished parts with out threads are then rolled. It is heat treated as per standard procedure to required grade as per the customer requirement and supplied in a finished condition to suit assembly requirements.

Figure 5 illustrates the actual invented product and its critical features. Prototype of this invention is made and tested for all the dimensional & mechanical properties and the results are found ok. Following are the tests Conducted
Vibration testing
Products tested with the following configuration in Junker type vibration testing machine for 50,000 cycles, there was no loss of preload.
Tensile testing
The parts are tested and found that the products are meeting the standard requirements as per ISO 898-Parti.
Torque tests
The parts are tested using both the features as per ISO 16047. The screw meets the requirement.
Advantages of using the SFL special design bolt
The Product intended to serve the needs of both the sectors, that is Hexalobular tightening feature for the OEM's and Hexagon for the service industry.
The product can be tightened using any of the features. Also the feature can be used after tightening for minor adjustments.
Hex can be used for post assembly correction of fastener, where the space for mix conventional six lobular tool bit is not feasible due to lack of space.
The invention elaborated used hex lobular synonymous with hexalobular and hence should not be construed different to limit the scope of the invention

We claim:
1. A screw having hex lobular driven head and hexagon load bearing flange.
2. The screw as claimed in claim 1, wherein the head comprises symmetrical and
equi-spaced six lobes.
3. The screw as claimed in claim 1, wherein the flange comprises symmetrical and
equi-spaced six sides.
4. The screw as claimed in claim 1, wherein the screw is of pre-determined length
based on its application.
5. The screw as claimed in claim 1, wherein the hex lobular driven head thickness
is equal to the hexagon load-bearing flange.
6. The screw as claimed in claim 1, wherein the hex lobular driven head and the
hexagon load-bearing flange have common wrench height.
7. The screw as claimed in claim 1 is manufactured using cold forging technique.
8. A method of fastening objects comprising utilizing at lease one screw as
described in claim 1 for fastening the objects.