FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"High Bending Strength Sheet-Metal Structure And Method For Production
Thereof
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & TOUBRO LIMITED,
L&T House, Ballard Estate, P. O. Box: 278, Mumbai 400 001, India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

High Bending Strength Sheet-Metal Structure And Method For Production
Thereof
Field of the invention
The present invention relates to sheet-metal structure, and more particularly, high bending strength sheet-metal structure and method for production thereof.
Background of the invention
High strength is achieved in sheet metals by providing strengthening ribs on the sheet metal components. The process of providing these strengthening ribs is carried out with the help of a punching tool. The punching tool (200) consists of two parts, a die (120 and a punch (130). The die (120) has a cavity and the punch (130) has a protrusion, both designed with the same shape as the desired rib. During the process of ribbing on the sheet metals, the punch (130) is forced into the sheet metal (122) forming a rib (124) which takes the shape of the punch within the cavity of the die as shown in figure 1. These strengthening ribs may be made on flat surfaces or on edges, depending on where strength is required. The deeper the rib, the higher is the strength.
Current technologies include a single level strengthening ribs as shown in figure 2.The limitation of the single level rib is that the depth of the rib marked as 'X' in Figure 3 is limited by fracture point of the sheet metal.
Accordingly, there exists a need to provide a method for ribbing the sheet metal which overcomes drawbacks of the prior art.
Objects of the invention
An object of the present invention is to distribute areas of elongation at different levels of a sheet metal thereby, not reaching the fracture point at any area on the structure.

Summary of the invention
Accordingly, the present invention provides a sheet-metal structure having high bending strength. The sheet-metal structure comprises a first platform/wider rib embossed thereon, a plurality of second embossed platforms/ribs embossed on the first embossed platform thereby providing a further depth to the sheet-metal structure and optionally a third platform/rib embossed on each rib of the plurality of second ribs to achieve further depth in the sheet-metal structure. Wherein embossing the sheet-metal structure at different levels distributes the area of elongation amongst different levels without reaching the fracture point thereof.
Brief description of the drawings
Figure 1 shows a simplified punch tool forming a rib on a metal sheet, in accordance with the prior art;
Figure 2 shows a 3D view of a sheet metal component with rib structure at its bent edge in accordance with the prior art;
Figure 3 shows a view of a ribbing technology aligned with its axis, achievable depth marked, in accordance with the prior art;
Figure 4 shows a view of an ribbing technology aligned with its axis, in accordance with the present invention;
Figure 5 shows a perspective view of a sheet metal component with rib structure at its bent edge in accordance with the present invention;
Figure 6 shows a multilevel instance, in accordance with the present invention;
Figure 7 shows the area of elongation of the sheet metal as a result of a ribbing operation of figure 4; and

Figure 8 shows a distribution of the areas of elongation amongst various levels enabling the achievement of deeper ribs.
Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The present invention provides a sheet-metal structure having high bending strength The sheet-metal structure distribute areas of elongation at different levels of a sheet metal thereby, not reaching the fracture point at any area on the structure
Referring now to figure 4 to 8, there is shown a sheet-metal structure (100) in accordance with the present invention. The sheet-metal structure (100) comprises a first platform/wider rib (10) embossed on a bend/surface (20) thereof. The first platform/wider rib (10) serves as a base or level 1 as shown in figure 4.
Further, the sheet-metal structure (100) includes plurality of second embossed platforms/ribs (30) embossed on the first embossed platform (10) thereby providing a further depth to the surface (20) seen as level 2 in figure 4. Figure 5 shows a perspective view of the configuration having the second embossed platforms/ribs (30) embossed on the first platform/wider rib (10) serving as a base.
The sheet-metal structure (100) optionally includes a third platform/rib (40) embossed on each rib, for example a rib (22) of the plurality of second ribs (30) to achieve further depth in the metal sheet. Embossing the bend/surface (20) of the sheet-metal structure (10) at different levels, distributes the area of elongation (AB) amongst different levels without reaching the fracture point thereof. In an embodiment, further levels of embossing the platforms /ribs levels on previous platforms /ribs levels may be done to

achieve further strength to the sheet-metal structure (100). Specifically, figure 6 shows for an instance of a multilevel rib with three levels.
The depth of the ribs as marked X in figure 3 are limited only by the material's fracture point. When the rib is formed on the surface (20) of the sheet-metal structure (100), the elongation happens on the walls of the rib as shown in figure 7.
The structure embodied in this invention overcomes this difficulty and allows for deeper ribs without reaching the fracture point by distributing its areas of elongation amongst different levels as shown in figure 8.
Advantages of the invention
1. The sheet-metal structure (100) provides higher strength to a bend, as compared to
the conventional rib, in sheet metal.
2. The sheet-metal structure (100) allows deeper formation of strengthening rib without tearing the metal.
3. The sheet-metal structure (100) allows deeper formation of strengthening rib without increasing wear and tear of the forming tool.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We claim
1. A sheet-metal structure having high bending strength, the metal sheet comprising:
a first platform/wider rib embossed on bend of the sheet-metal structure;
a plurality of second embossed platforms/ribs embossed on the first embossed platform thereby providing a further depth to the sheet-metal structure; and
optionally a third platform/rib embossed on each rib of the plurality of second ribs to achieve further depth in the metal sheet,
wherein embossing the sheet-metal structure at different levels distributes the area of elongation amongst different levels without reaching the fracture point thereof.