FIELD OF INVENTION
The present invention relates to an improved method of end cutting of rolled tubes in a vertical cold sawing machine after an automatic alignment in the manufacturing of seamless steel tubes. More particularly the invention relates to an improved method of end cutting of tubes carrying out a process of automatic alignment for the purpose of marking of tubes at a specified distance from tail end.
BACKGROUND OF THE INVENTION
Manufacturing of hot finished tubes involves metal deformation processes during which the raw material [bloom/billet] is converted into a finished tube. The type and number of deformation processes can vary from process to process based on final specification [Outside diameter, wall thickness and length] of the tube. The process used during this invention involves three major metal deformation processes namely cross piercing & elongation, pushing and rolling.
Blooms manufactured through concast casting are used as raw material for making finished tubes. These blooms are cut using gas cutting operation into billets. These billets are then charged to a rotary heart furnace, which heats up the billets from room temperature to a temperature of 12500C to 13000C. It is then the billets are taken

for first major metal deformation process-cross piercing and elongation. At this stage the solid billet is converted to a hollow having through hole. Wall thickness, outer diameter and length are controlled by adjusting the control parameters of the cross piercing and elongation mill. The desired dimensional characteristics are obtained by using a suitable plug and adjusting gaps between rolls and discher discs of cross piercing and elongation mill.
The hollow bloom is now moved for the next metal deformation process using transfer arms and robotic manipulator. Pushing is the second major metal deformation process after cross piercing and elongation, where inside diameter is controlled by using a heated mandrel, while outside diameter is controlled by using multiple fixed stands of successively decreasing caliber. The mandrel is heated in a separate roll down furnace to a temperature of 400-4500C and inserted in the hollow bloom before one end of the hollow bloom is crimped to get it seated on mandrel. Now, hollow bloom crimped at one end and with heated mandrel inside is pushed through fixed set of stands of push bench. Wall thickness, outside diameter and length of the pushed shell are depending upon the reduction percentage chosen per stand in the push bench. That is, dimensional characteristics for the pushed shell are controlled by caliber of the push bench stand.

Shell obtained after second major metal deformation process is separated from mandrel before moving on to rolling operation. The loosening of shell from mandrel is done in a loosening mill i.e. reeler, which consist of 2 set of hyperbolic profiled rolls, the distance between which is set according to dimension of the shell and angles of the rolls are adjusted to ensure maximum contact of the shell and mandrel at the center of rolls. After loosening the mandrel from shell, mandrel is removed in the extraction mill which consists of a die whose inside diameter is larger than mandrel outside diameter but smaller than shell outside diameter.
After separating the shell from the mandrel in extraction mill, it’s crimped end is cut in the hot saw. Now, the shell is charged inside a reheating furnace to ensure that the third and final metal deformation process – rolling – takes place above the recrystallization temperature of iron. The reheated shell is fed to the rolling mill, which consists of individual motor driven stands for final shaping of the tube.
Rolling which is the final metal deformation process for manufacturing of seamless steel tubes is carried out using number of stands with rolls driven by motors. These stands are designed to ensure gradual reduction in shell size to achieve the targeted tube dimensions [Outer diameter, wall thickness and length]. Unlike, the previous two metal deformation processes of cross piercing & elongation and pushing,

in rolling no plug or mandrel is used. In fact the outer diameter is controlled by calibers of Stretch Reducing Mill [SRM] stands and wall thickness is controlled by motor speeds.
Stretch Reducing Mill [SRM] is capable of rolling tubes to a length of maximum 60 meters which needs to be cut to required lengths (thickened ends on both the sides and one/two cuttings at the middle based on the requirement).
Referring to Fig. 1 The Existing practice of stopping and aligning layer of tubes with thickened end less than 2.5 metres is by inserting a channel of sufficient size on a fabricated steel structure in line with flat rollers. The flat rollers are used for transporting layer of hot rolled tubes. The channel after alignment of tubes is removed out for transporting the tubes to the sawing machine. This practice of manually aligning the tubes consumes time and was also an unsafe activity. For tubes having thickened ends of length less than 2.5 meters, the existing facility for stopping and aligning of tubes before cutting of thickened ends is not suitable. So there is a need to find out a simplified design of automatic disappearing stopper to be fabricated and erected in the system of manufacturing seamless steel tubes which facilitates stopping and aligning of tubes with thickened end less than 2.5 meters. This was a major challenge faced in cold sawing and the new invented disappearing stopper with pneumatic cylinders overcomes the problem.

OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose an improved method of end cutting of rolled tubes in a vertical cold sawing machine after an automatic alignment in the manufacturing of seamless steel tubes, which is capable of stopping and aligning of tubes for marking of the tubes at a specific distance from tail end and transporting the marked tubes to sawing machine to cut the same.
Another object of the invention is to propose an improved method of end cutting of rolled tubes in a vertical cold sawing machine after an automatic alignment in the manufacturing of seamless steel tubes, which is capable of eliminating the disadvantages of unsafe and time consuming manual method of aligning the tubes making a substantial saving in time and cost.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: Shows the arrangement of cold sawing machine, roller conveyors for tube
transportation, in the existing method.
Figure 2: Shows the sketch of newly invented disappearing stopper in position.
Figure 3: Shows the constructional features of the disappearing stopper with
pneumatic cylinders arrangement.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Referring to Fig. 2 Arrangement of cold sawing machine (1) with the saw blade (4), roller conveyors for transportation of tubes, Length stopper (3) and tail end stopper (5) are configured in the system of manufacturing seamless steel tubes as shown in figure 2. Layer of tubes from Stretch Rolling Mill after natural cooling at cooling bed are transported to cold sawing machine (1) by means of flat roller conveyors (not shown). Layer of tubes in which the tail end needs to be cut is stopped and aligned at the newly invented disappearing stopper (5). After aligning, the layer of tubes are marked at a specified distance from tail end and the tubes will be transported to sawing machine. Layer of tubes is cut at marked point. The tail ends is scraped out and the tubes at the required length are transported to the next work center for further operation.
Construction of newly invented disappearing stopper is shown in figure 3. It consists of stopper plate (5) with damper plates inside (not shown) to absorb shock while the tubes hit the stopper. The stopper plate (5) is connected to the pneumatic cylinders (7) which slides the stopper plate (5) up and down. The stopper plate (5) at down position stops and align the tubes. After alignment of tubes, the layer of tubes is marked at a specified distance from tail end to cut the excess length obtained in the manufacturing process and then stopper plate (5) is raised up by the control valves (6)

for transportation of tubes further to the sawing machine and the excess scrap material is removed. The up and down movement is achieved by pneumatic directional control valves (6) connected to the cylinders (7) through pipelines (8). The whole assembly is fixed to the base frame which in turn is grouted to the ground.
The method as described above stops the tubes and specified/required distance marked to cut the excess length obtained in the manufacturing process. The method as described above after marking will be transferred to the cutting machine and the excess scrap material is removed.

WE CLAIM
1. An improved method of end cutting of rolled tubes in a vertical cold sawing
machine after an automatic alignment in the manufacturing of seamless steel tubes comprising;
disposing a tail end/disappearing stopper (5) connected to a plurality of pneumatic cylinders (7) through pipelines (8);
a pneumatic directional control valve (6) configured to control the movement of the said stopper (5); wherein,
the disappearing stopper plate (5) is disposed in the system, the said stopper plate (5) having dampen plates inside to absorb shock while the tubes coming from previous operation hit the stopper plate (5), when the stopper plate (5) moves up and down by means of actuating said pneumatic cylinders (7) through control valves (6) to make an automatic alignment of tubes when the stopper plate (5) at down position stops and align the tubes wherein, the layer of tubes is marked at a specific distance from tail end when the stopper plate (5) is raised up by the control valves (6) transporting the tubes to the cold sawing machine (1) after natural cooling at cooling bed to cut the excess length obtained in the manufacturing process as per the marking when the whole assembly is fixed to the base frame which in turn is grouted to the ground.

2. The improved method as claimed in claim 1, wherein the disappearing stopper (5) is fabricated and erected in the system to facilitate stopping and aligning of tubes.