FIELD OF THE INVENTION:

[001] The present invention relates to a process for the fabrication of the formed boom of Mobile Cranes. More particularly, the present invention, relates to the process for the fabrication of Bottom Channel and Top Channel from high strength steel plates, which are subsequently welded together to make the Formed Boom sections.
BACKGROUND OF THE INVENTION:
[002] Booms of Tyre Mounted Mobile Cranes are critical structural component, as the loads are lifted by means of a hoisting winch driven hook block which is suspended from the Boom Head of the outermost (“fly”) boom section. These booms comprise of several sections which may be telescoped out (by means of hydraulic cylinders) to extend to the required length for achieving the desired height and reach. The formed boom sections are in general of rectangular or trapezoidal sections of welded 4 (four) plate construction. High strength steel is used in general for boom construction. However, the requirement of ever increasing boom lengths and higher load carrying capacity have seen the advent of booms of formed cross section – these are fabricated by welding together two bent profiles (top & bottom) in the neutral axis (on the side). It is important to ensure accuracy of the dimensions of the formed sections in order to ensure smooth telescoping movement, structural integrity and load carrying capability.
[003] US6403179B1 discloses a polygonal composite structure is formed using a filament winding process. The composite structure formed on a mandrel having a longitudinal axis, comprises an inner structural layer, an outer structural layer, and a plurality of corner pieces. The inner and outer structural layers are formed by winding a fibre reinforcement material, having a resin applied thereon, about a mandrel. The fibre reinforcement material is oriented at a winding angle relative to the longitudinal axis. Each of the plurality of corner pieces is located at each corner of the polygonal structure between the inner structural layer and the outer structural layer. Each of the plurality of corner pieces is oriented lengthwise along the length of the structure. The number of corner pieces is equivalent to the number of sides of the structure.
[004] US5495654A discloses a Flat-rolled sheet metal is manufactured to preselected gage, mechanical properties and surface finish and is fabricated into unitary sheet metal shingle structures with interlocking folded over sheet metal layers providing for ease of assembly and weather proofing along each side of a rectangular configuration portion which remains exposed after assembly of shingle structures in side-by-side interlocked relationship in a horizontal direction, and in overlapping partially-covering relationship in a vertical direction. Galvanized mild steel provides lightweight, high-tensile strength, impact-resistant and long-service-life shingle structure. Finish coating enables selection of coloring and thermosetting polymeric coatings facilitate embossing of exposed portions to simulate the appearance of cedar shakes or other types of shingles.
[005] There are very few process of fabrication of the formed boom. Therefore in presence of the aforesaid back drop the present invention provides a process for fabrication of the formed booms in efficient and accurate manner without the usage of customized tooling.
OBJECTIVES OF THE INVENTION:
[006] One objective of the present invention is to provide a process for the fabrication of Formed Booms, each section of which comprises of one Top Channel and another Bottom Channel.
[007] Yet another objective of the present invention is to provide a process for the fabrication of the formed booms for Tyre Mounted Mobile Cranes and other similar machinery performing the same tasks that utilizes formed booms.
[008] Yet another objective of the present invention is to provide a process for the fabrication of the formed booms by way of usage of standard tools and equipment in place of customized dies, thus saving money and reducing lead time.
[009] Yet another objective of the present invention is to provide a process for the fabrication of the formed booms by way of designing a novel and unique system for generating the inputs for the bending process ensuring repeatability of operations and delivering accurate product.
[010] Yet another objective of the present invention is to provide a process for the fabrication of the formed booms by way of designing unique system for the division of the steel plate into segments and deriving & providing as input, the angle for each segment.
SUMMARY OF THE INVENTION:
[011] The present invention relates to a process for the fabrication of the Formed Boom of Mobile Cranes. More particularly, the present invention relates to the process for the fabrication of the Bottom Channel and Top Channel (which are subsequently welded together to make the Formed Boom sections), wherein inputs for the bending process are generated in such a way that makes the process repeatable, accurate and achievable with the help of simple tooling. It starts with the division of the total arc segment into a number of straight line segments and then subjecting each segment to bending at calculated angles to achieve the desired profile which is based on the theory that an arc or circular section comprises of an infinite number of straight lines, where each segment of straight line is at an angle to the adjacent segment.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
[012] The present invention will be described in more detail hereinafter with the aid of the description which relates to preferred embodiments of the invention explained with reference to the accompanying schematic drawings, in which:
Fig. 1 shows typical Bottom Channel;

Fig. 2 shows typical Bottom Channel with marked-up tangent lines for explaining the concept;
Fig. 3 shows typical Top Channel;
Fig. 4 shows typical Channel weldment;
Fig. 5 shows flat pattern of Bottom channel profile, wherein the relative angles shown against each of the bending Lines.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:
[013] 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.
[014] Accordingly, in one embodiment of the present invention describing a process for the fabrication of the formed boom through Fig. 1 to Fig. 4 that describes the overall process for fabrication of the formed boom. Fig. 5 shows the table of corresponding relative angles against each of the bending lines in the flat pattern of Bottom channel profile.
[015] In one embodiment of the present invention is to provide a process leads to the following process for the fabrication of the formed boom, which is as follows:
wherein the fabrication of the Bottom channel (Fig.1) comprises the steps of:
- placing the flat plate as per flat pattern to the brake press and check the position of the bending lines of the Top channel already marked through nitrogen during cutting along with checking for dimensional and diagonal accuracy of the cut plate.
- performing radius bends at the corners to form the profile with the help of the standard tooling such as R10 punch, 120mm V opening die each of 12m length (each of the dimension length is 832 mm), whereas the corner radii are close to 80mm and hence there has to multiple bumping with R10 radius punch to get the desired radius and the 10 bending lines in each flat plate, whereas the flat plate having spring back effect.
- performing progressive radius bends at each bending lines upon a pre-defined angle, whereas the machine back gauge movement is programmed to the value taken from the distance between any two bending lines.
wherein the fabrication of the Bottom channel (Fig.3) comprises the steps of:
- placing the flat plate as per flat pattern to the brake press and check the position of the bending lines of the Bottom channel already marked through nitrogen.
- performing radius bends at the corners to form the profile with the help of the standard tooling such as R10 punch, 120mm V opening die each of 12m length (each of the dimension length is 832 mm), whereas there are 30 bending lines in each flat plate having spring back effect.
- performing progressive radius bends at each bending lines upon a pre-defined angle and the machine back gauge movement is programmed to the value taken from the distance between any two bending lines.
- the above steps are repeated for all the marking lines and finally a semi-circular Bottom channel profile is generated.
- the R40 radii at two corners of the Bottom channel are achieved through multiple bends depending on the final width of the channel.

wherein, the Bottom and Top channel profiles are weld together to form the complete Boom as depicted in Fig. 4.
[016] In another embodiment of the present invention Fig. 2 depicting the Bottom channel with marked-up tangent lines for explaining the concept wherein each tangential segments having 27mm of spacing’s.
[017] In another embodiment of the present invention Fig. 4 describing the weldment of the Bottom channel and Top channel profile.
[018] In another embodiment of the present invention Fig. 5 shows the table of relative angles against the each bending lines.
[019] Yet another embodiment of the present invention the spring back effect of the Top and Bottom channel depends on thickness of the plate, grade of the material, rolling process (including the direction) of the manufacturer, quenching and damp, V opening, process of bending (Bottoming or Air Bending).
[020] In another embodiment of the present invention the technical results of the Spring Back describing through the following Tables:
Table: 1
2015 – Trial Case results on TIL existing 5m long 340T CNC Press Material – S690QL

Table: 2
2015 – Trial Case results on TIL existing 8m long 650T CNC Press Material – S690QL

Table: 3
2016 – Trial Case results on 13m long 450MT x 2 Tandem CNC Press Material – S690QL

[021] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description only, these are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously modifications remain possible, in particular from the point of view of the design of the various elements or by substitution of equivalent methods, without thus departing from the scope of protection of the invention.
,CLAIMS:We Claim (s):
1. A process for the fabrication of the formed boom of the mobile cranes, wherein the process incudes fabrication of the Bottom channel and fabrication of the Top channel and finally welding of the Bottom and Top channel together to form the boom, whereas -
the fabrication of the Top channel comprising the steps of:
- placing the flat plate as per flat pattern to the brake press and check the position of the bending lines of the Top channel already marked through nitrogen during cutting along with checking for dimensional and diagonal accuracy of the cut plate.
- performing radius bends at the corners to form the profile with the help of the standard tooling such as R10 punch, 120mm V opening die each of 12m length (each of the dimension length is 832 mm), whereas the corner radii are close to 80mm and hence there has to multiple bumping with R10 radius punch to get the desired radius and the 10 bending lines in each flat plate, whereas the flat plate having spring back effect.
- performing progressive radius bends at each bending lines upon a pre-defined angle, whereas the machine back gauge movement is programmed to the value taken from the distance between any two bending lines.
the fabrication of the Bottom channel comprises the steps of:
- placing the flat plate as per flat pattern to the brake press and check the position of the bending lines of the Bottom channel already marked through nitrogen.
- performing radius bends at the corners to form the profile with the help of the standard tooling such as R10 punch, 120mm V opening die each of 12m length (each of the dimension length is 832 mm), whereas there are 30 bending lines in each flat plate having spring back effect.
- performing progressive radius bends at each bending lines upon a pre-defined angle and the machine back gauge movement is programmed to the value taken from the distance between any two bending lines.
- the above steps are repeated for all the marking lines and finally a semi-circular Bottom channel profile is generated.
- the R40 radii at two corners of the Bottom channel are achieved through multiple bends depending on the final width of the channel.

2. The process for the fabrication of the formed boom of mobile cranes as claimed in claim 1, wherein the boom formation first starts with division of the total arc segment into a number of straight line segments and then subjecting each segment to bending at calculated angles to achieve the desired profile which is based on the theory that an arc or circular section comprises of an infinite number of straight lines, where each segment of straight line is at an angle to the adjacent segment.

3. The process for the fabrication of the formed boom of mobile cranes as claimed in claim 1, wherein the Bottom channel profile divided into tangential segments of each 27mm of spacing.

4. The process for the fabrication of the formed boom of mobile cranes as claimed in claim 1, wherein the spring back effect of the Top and Bottom channel depends on thickness of the plate, grade of the material, rolling process (including the direction) of the manufacturer, quenching and damp, V opening, process of bending (Bottoming or Air Bending).

5. A formed boom of mobile cranes comprising the Bottom channel and the Top channel profile through the process as claimed in claims 1 to 4.