DESC:
FIELD OF INVENTION

The present invention relates to a ribbed Thermo Mechanically Treated (TMT) bar with improved surface rib pattern profile for high adherence, particularly for reinforcements for concrete or welded mesh, equipped ribs inclined with respect to the central axis. More particularly, the present invention is directed to developing TMT bars having higher bond strength and higher Mean Projected Rib Area (AR Value) properties of said TMT rebars by optimizing design of surface longitudinal and transverse ribs.

BACKG ROUND OF THE INVENTION

It is well known in the related art that thermo mechanically treated steel reinforcement bars are being used in RCC application. It has also been experienced in the art that considering the safety aspect of such construction, there had been a need to develop steel materials with even higher bond strength with same section for the TMT bars to suit application in RCC.

In the prior art an European specification EP399910B1 by ACOR ACIERS DE CONSTRUCTION RA discloses a ribbed steel rod with high adherence, particularly for concrete reinforcements, which is deformed by cold rolling and provided, by cold working, with ribs which are inclined with respect to the axis of the rod and disposed between narrow longitudinal straight portions which are not ribbed, comprises four narrow longitudinal straight portions which are not ribbed between which are disposed four series of ribs inclined with respect to the axis of the rod.

Reference has also been made to Indian Patent Application 1149/KOL/2012, referring Figure 1A, which discloses an improved surface rib pattern profile thermo mechanically treated (TMT) bar with high bond strength comprising of two parallel longitudinal ribs along the diameter and a plurality of parallel spaced transverse ribs disposed between longitudinal ribs inclined relative to the axis of the rod and that the transverse are equidistant between each other and are oriented with the same angular orientation and equal spacing with respect to the longitudinal rib of the rod. Each rib has, in section along a plane perpendicular to the axis of the rib with a substantially trapezoidal /parabolic profiled flanks inclined at an angle 65 – 70 degrees with respect to the longitudinal rib and more preferably to 68 degrees. The Space with transverse and longitudinal rib = 0.15D max and more preferably 0 mm.

IN 3713/Del/2013 discloses method of manufacturing TMT Bars with patterns of double transverse ribs, wherein in one preferred embodiment of TMT bar with pattern of double transverse ribs made by the said method herein, first angle for first pattern of transverse ribs is preferably selected and created using said Die-sets in the range of 69 degrees to 71 degrees with respect to the longitudinal rib therein and the second pattern of transverse ribs is created in the range of 53 degrees to 55 degrees.

Reference has also been made to IN 201631004862 which discloses improved TMT bars wherein the included angle or angle of transverse rib varies between 35 degrees to 48 degrees depending upon the diameter of the bar.

Figure 1B illustrates a commercially available TMT bar having an x shaped rib pattern. However, these existing rib patterns have lower AR values since their transverse ribs have the same angle.

Therefore, there remains a need for an advance double rib design having different degrees in its two transverse ribs to overcome the drawbacks of prior arts.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention.

It is thus the intent of the present invention to overcome the limitation of the existing TMT bars used for RCC structures by developing a new surface rib pattern profile of steel TMT rebars capable of ensuring higher bond strength with concrete or other grout material for composites and higher Mean project rib area (AR values). Such high bond strength rebars is developed and produced by selectively controlling mass of transverse surface ribs of the steel bar material and on the other hand optimizing the process of roll cutting for hot deformed rebars to thereby obtain desired resistance to pull out through composite thereby achieving desired superior bond strength properties in the end products and a better protection against earthquake protection.

The first aspect of present invention is to provide an improved surface rib pattern profile thermos mechanically treated (TMT) bar comprising of (i) a plurality of first parallel spaced transverse ribs inclined relative to axis of the bar and (ii) a plurality of second parallel spaced transverse ribs inclined relative to the axis of the bar, in a direction opposite to the plurality of first parallel spaced transverse ribs making a double “Y” pattern of the ribs and that the transverse ribs are equidistant between each other and are oriented with the same angular orientation and equal spacing with respect to the axis of the bar; wherein the angle of the plurality of first parallel spaced transverse ribs is in the range of 55-62° and the angle of the plurality of second parallel spaced transverse ribs is in the range of 45-56° with respect to the axis of the bar.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

The above and other aspects, features and advantages of the embodiments of the present disclosure will be more apparent in the following description taken in conjunction with the accompanying drawings, in which:

Figures 1(a-b) shows rib designs as prior art of the present invention.

Figure 2 shows advance double Y-rib design as per present invention, (a) reading front view of the TMT bar, (b) reading back view of the TMT bar, (c) rolling front view of the TMT bar and (d) rolling back view of the TMT bar as per present invention

DETAILED DESCRIPTION OF INVENTION

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure and their equivalents.

It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

The terminology used herein is for the purpose of describing particular various embodiments only and is not intended to be limiting of various embodiments. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features, integers, steps, operations, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, components, and/or groups thereof. Also, Expressions such as "at least one of," when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

The present disclosure will now be described more fully with reference to the accompanying drawings, in which various embodiments of the present disclosure are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the various embodiments set forth herein, rather, these various embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the present disclosure. Furthermore, a detailed description of other parts will not be provided not to make the present disclosure unclear. Like reference numerals in the drawings refer to like elements throughout.

The subject invention lies in a ribbed Thermo Mechanically Treated (TMT) bar with improved surface rib pattern profile for higher adherence with surrounding cement or grout material. The high bond strength TMT bar according to the invention ensures high composite action ensure favouring wide scale application such as reinforcement bar in RCC structures or as rock bolts for effective roof support in underground mines or tunnel construction. The modified ribbed TMT bars have application particularly for reinforcements for concrete, in general.

Figure 2 (a-d) illustrates an embodiment of present invention which relates to an improved surface rib pattern profile thermos mechanically treated (TMT) bar comprising of (i) a plurality of first parallel spaced transverse ribs (1) inclined relative to axis of the bar and (ii) a plurality of second parallel spaced transverse ribs (2) inclined relative to the axis of the bar, in a direction opposite to the plurality of first parallel spaced transverse ribs making a double “Y” pattern of the ribs and that the transverse ribs are equidistant between each other and are oriented with the same angular orientation and equal spacing with respect to the axis of the bar; wherein the angle of the plurality of first parallel spaced transverse ribs is in the range of 55-62° and the angle of the plurality of second parallel spaced transverse ribs is in the range of 45-56° with respect to the axis of the bar.

Another embodiment relates to an advanced double Y-rib having different degree in two transverse ribs (58-46 degrees).

Yet another embodiment of present invention discloses spacing of transverse ribs to be around 9.2 mm.

Another embodiment of present invention provides perpendicular angle having half rib inclination.

Another unique embodiment of present invention relates to Mean projected rib area, AR value is around 3.8 mm2/ mm.

Due to this special design modification present invention provides a closed rectangle box for enhanced surface bonding and double load bearing axis on surface to reduce the friction co-efficient.

In the general rib pattern illustrated in Figure 1a, there is only one sided transverse rib pattern across the length which is at an angle of 72 degrees. The spacing of transverse rib is around 7.6 mm. No additional and perpendicular rib has been reported in case of general rib pattern cases. Further, the Mean projected rib area, AR value for these TMT bars is around 2.26 mm2 /mm having open surface bonding having weaker bond strength.

In the commercially available WinGrip technology, as illustrated in Figure 1b, the rib pattern has the same 49 degrees angle for the two different transverse ribs. Additional rib inclination is also present which is around 90 degrees. Further, the Mean projected rib area, AR value for these TMT bars is around 1.89 mm2 /mm having open surface bonding having weaker bond strength.

In one of the exemplary embodiment of present invention relates to comparison in different technologies already available with Advance double Y-rib pattern of present invention tabulated below:

Comparison of Transverse Rib Pattern
Sl. No. General Rib Pattern Win Grip Rib Pattern Advanced Double Y-Rib Pattern (Present invention)
1 This is only one sided transverse rib across the length (72°) Win Grip Rib Pattern having same degree in different two transverse rib (49°) In Advance double Y-Rib having different degree in two transverse ribs (58-46°)
2 Spacing of transverse rib is less than win grip rib and Advance Double Y-rib (7.6 mm) Spacing of transverse rib is more than General and Advance Double Y-rib (13.07 mm) Spacing of transverse rib is less than Win Grip TMT and more than general TMT (9.2 mm)
3 No Additional and perpendicular rib Additional rib inclination (90°) is present in Win Grip In perpendicular Angle having half rib inclination (46°)
4 Length of transverse is less than win grip rib and advance double y-rib Length of transverse rib more than other TMT Length of transverse rib is less than Win Grip
5 Ar Value 2.26 mm2/ mm Ar Value 1.89 mm2/ mm Ar Value 3.8 mm2/ mm
6 Open surface bonding Open surface bonding A closed rectangle box to enhancing surface bonding
7 Not found Not found Double Load Bearing axis on surface to reducing the friction co-efficient

Spacing of transverse rib change with the change of transverse rib degree resulting in change of length of transverse rib. Some of the examples provided below proves that Mean projected Area (AR value) mainly depends on degree, spacing, depth and length of transverse rib.

Degree( Sin?) Value (Sin?) Spacing of transverse rib (mm) Depth of transverse rib (mm) Length of transverse rib (mm) Atr (mm²) Ar value (mm²/mm)
30° 0.500 10 0.8 39.4 21.01 2.10
35° 0.573 10 0.8 34.2 18.24 2.09
40° 0.643 10 0.8 30.6 16.32 2.10
45° 0.707 10 0.8 27.5 14.67 2.07
50° 0.766 10 0.8 25.9 13.81 2.12
55° 0.819 10 0.8 24.5 13.07 2.14
60° 0.866 10 0.8 23.9 12.75 2.21
65° 0.906 10 0.8 22.3 11.89 2.16
70° 0.94 10 0.8 21.9 11.68 2.20
75° 0.966 10 0.8 20.2 10.77 2.08
90° 1.00 10 0.8 19.5 10.40 2.080

ADVANCED DOUBLE Y-RIB (Present Invention)

Degree( Sin?) Value (Sin?) Spacing of transverse rib (mm) Depth of transverse rib (mm) Length of transverse rib (mm) Atr (mm²) Ar value (mm²/mm)
45° 0.707 9.1 0.8 10.8 5.76 0.90
50° 0.766 9.1 0.8 10.8 5.76 0.97
55° 0.819 9.1 1.05 22.5 15.75 2.84
60° 0.866 9.1 1.05 23 16.10 3.06

From the above tables, it may be inferred that the advanced double Y-rib TMT bar of the present invention having different angles in its two transverse ribs provides superior AR value which results in superior bonding with concrete when compared to the existing TMT bar designs.
,CLAIMS:1. An improved surface rib pattern profile thermos mechanically treated (TMT) bar comprising of (i) a plurality of first parallel spaced transverse ribs (1) inclined relative to axis of the bar and (ii) a plurality of second parallel spaced transverse ribs (2) inclined relative to the axis of the bar, in a direction opposite to the plurality of first parallel spaced transverse ribs making a double “Y” pattern of the ribs and that the transverse ribs are equidistant between each other and are oriented with the same angular orientation and equal spacing with respect to the axis of the bar; wherein the angle of the plurality of first parallel spaced transverse ribs is in the range of 55-62° and the angle of the plurality of second parallel spaced transverse ribs is in the range of 45-56° with respect to the axis of the bar.

2. The improved surface rib pattern profile thermos mechanically treated (TMT) bar as claimed in claim 1, wherein the angle of the plurality of the first parallel spaced transverse ribs (1) is in the range of 57-60° and the angle of the plurality of second parallel spaced transverse ribs (2) is in the range of 47-55° with respect to the axis of the bar.

3. The improved surface rib pattern profile thermos mechanically treated (TMT) bar as claimed in claim 1, wherein the spacing of transverse ribs is about 9.2 mm.

4. The improved surface rib pattern profile thermos mechanically treated (TMT) bar as claimed in claim 1, wherein the Mean projected rib area, AR value is 3.8 mm2/ mm.