FIELD OF THE INVENTION
The present invention generally relates to the field of rod bending/forming process. More particularly, the invention relates to an improved process of forming U rod hanger support for suspending the boiler components like headers, drums, pipelines in Power Plant.
BACKGROUND OF THE INVENTION :
'U' Rods are essentially used for suspending various boiler components like headers, drums, pipelines in Power Plant.
U' rod hanger support is a rod bent/formed into a U shape which has threads at the ends of the straight limbs. The component is suspended by means of the U rod hanger support from the supports provided in the ceiling.
There are generally three known methods by which the U rod hanger supports are manufactured.
Method 1: Cold bending of rods. The ends of the rods are threaded. The rod is then bent progressively against a bending former. This is normally used for small diameter rods.
Method 2: Hot forming by rotary bending. Two joints are introduced between the U rod and the straight limbs. The straight limbs are threaded separately. The rod meant for the U portion is heated and bent in rotary bending machine separately. The two ends of the U rod, so formed, are edge prepared and welded with the already prepared straight rods to form a complete hanger support. This method is normally applicable to the Drum suspension rod whose diameter is around 125 mm to 200 mm.

Method 3: Hot forming by pressing. Similar to method 2, the U rod is separately hot pressed and joined with the straight limbs. The straight limbs are threaded separately. To form the U rod, the straight rod is heated and formed into U in a hydraulic press using a special forming dies. The two ends of the U rod, so formed, are edge prepared and welded with the already prepared straight rods to form complete hanger support. This method is applicable for manufacturing alloy-steel (F91) hanger supports.
However, the prior art U-rod, hanger supports have the disadvantages of joining the constituent parts by welding, which reduces the operating life of the supports.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved process of forming U-rod hanger support for suspending the boiler components.
Another object of the invention to propose an improved process of forming U-rod hanger support for suspending boiler components, which is hot-formed without welding joint.
SUMMARY OF THE INVENTION
According to the invention, there is provided an improved process of forming U-rod hanger support for suspending the boiler components, comprising the steps of:
- cutting a straight rod to a desired length;
- threading the ends of the straight rod corresponding to the requirement of the suspendable components;

- protecting the threaded portions by means of a cap;
- heating the straight rod in a furnace to a bending temperature depending on the material specification;
- removing the rod from the furnace and placing the rod between the rollers and the forming die of a hydraulic press;
- pulling the forming die by means of a hydraulic cylinder of the hydraulic press;
- hot forming the rod according to the shape of the forming die;
- taking out the forming die and removing the bent U rod; and
- conducting the necessary post heat treatment of the supports.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1: Shows Prior art method for U' rod formation by pressing,
Fig. 2: Shows U shaped rod after pressing and welding process according to prior art.
Fig. 3: A schematic representation of a Machine Setup indicating the portions of die, rollers and hydraulic press according to the invention.
Fig.4: The position of the rod in between the die rollers of the machine according to the process of the invention.
Fig. 5: Rod bending by applying force with the help of the hydraulic press according to the invention.
Fig. 6: U' shaped rod produced after bending process according to the invention.

DETAILED DESCRIPTION OF THE INVENTION
As shown in Figure 1 & 2, according to the prior art practice followed for forming U rod; the rod is typically bent using a press. The straight portion is threaded and then welded to the bent portion to form a U rod.
Figure 3 - Shows a schematic illustration of the machine set-up used for the invention. The machine which is basically a horizontal hydraulic press designed to perform U rod forming. The Roller die setup is movable in and out towards the central axis of a punch setup. The punch setup is movable in and out towards the hydraulic press. The machine set-up allows implementation of an improved process of U rod forming within a short span of time; and without welding.
Figures 4-6 illustrates the sequence of operation for forming U rods according to the invention.
As shown in Figure 4, initially, the straight rod is cut to the required length and the ends are threaded as per requirement. The threaded portions of the rod are protected by means of a cap. The forming process requires that the rod is heated at certain temperature based on the material specification. Then the heated rod is placed above the roller dies such that the centre of the rod matches the centre of the forming dies.
Figure 5 shows that the force is applied through the hydraulic press for pulling the forming die to press the U rod. The pressing is carried out till the rod is bent to 180°. The pressing is carried out at the required temperature based on the material specification.
Fig. 6 - Shows that the forming die is removed and the U rod is taken out and necessary post heat treatment is carried out.

Examples
The Punch, Roller die & hydraulic setup for pressing 'U' rod were made. The rods tested and checked to ensure the length between the rods, bending temperature range and without any scale formation. Few trials were done successfully with P91 materials at the required temperature.
Similar procedure is followed for bending of Carbon steel rods &. few trials were done successfully with required length & temperature.

We Claim :
1. An improved process of forming U-rod hanger support for suspending the boiler components; comprising the steps of:
- cutting a straight rod to a desired length;
- threading the ends of the straight rod corresponding to the requirement of the suspendable components;
- protecting the threaded portions by means of a cap;
- heating the straight rod in a furnace to a bending temperature depending on the material specification;
- removing the rod from the furnace and placing the rod between the rollers of a hydraulic press and a set of forming die;
- pulling the forming die by means of a hydraulic cylinder of the hydraulic press;
- hot forming the rod according to the shape of the forming die;
- taking out the forming die and removing the bent U rod; and
- conducting the necessary post heat treatment of the supports.

2. An improved process of forming U-rod hanger support for suspending boiler components as substantially described and illustrated herein with reference to the accompanying drawings.

The invention relates to manufacturing of 'U' shaped rod hangers for suspending drums & headers in power boiler, material is used to withstand very high temperature. This process involves many sub-processes like bending, threading & welding which require lot of manpower & also a very time consuming process. To eliminate these difficulties, a new process is proposed. By manufacturing using the proposed setup & process, the welding process is eliminated completely & 'U' rod is manufactured easily just by pressing the lengthy rod at one stretch, thus saving cost, time and effort. It prevents scale formation & welding effects, thus leads to good quality product.