FIELD OF INVENTION
The present invention relates to a system and method for cooling mandrel head before push bench mill process to prevent deformation and to enhance the life of mandrel during manufacturing seamless steel tubes.
BACKGROUND OF THE INVENTION
Seamless steel tubes have been manufactured by the CPE- push bench mill process. In this process, a round billet previously heated to a hot rolling temperature by a heating furnace is pierced by the barrel type rolls of the piercing mill to form hollows which are short in length and very thick. Then the mandrel bar is placed inside the shell for end crimping and then is pushed along with mandrel through a series of three roll stands successively decreasing in diameter, which reduce the wall thickness of the hollow and elongate it into a shell. The shell is stripped from the mandrel and subjected to further size reduction in the stretch reducing mill to the required tube dimensions. The mandrel is being returned to a position in alignment with the push bench and is ready to receive another shell.
The pushing of the shell through the three roll stands generates a large amount of heat and the head of the mandrel (stepped end) particularly becomes very hot and

may be deformed. The mandrel head may be enlarged or step may be deformed with the remainder of the mandrel. If such mandrel is again employed, the interior finish of the tube may be marred and the thickened end loss will be high. If the deformation of the mandrel head is by way of enlargement, difficulty will be encountered in stripping the tube from the mandrel.
Mandrels for this use are generally made of special alloy steels at high expense, and it is desirable to keep the number on hand down to a relatively low figure. It is also desirable to employ the mandrels that they will be of uniform and constant dimension at the initiation of each tube forming operation. Hence the problem of thickened end loss and stripping problems can be overcome by a suitable method. Otherwise we have to replace the mandrel which is a costly affair and would result in spare shortage.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose a system and method for cooling mandrel head before push bench mill process to prevent deformation and to enhance the life of mandrel during manufacturing seamless steel tubes, which is capable of reducing the temperature of head of mandrel to prevent damage and deformation.

Another object of the invention is to propose a system and method for cooling mandrel head before push bench mill process to prevent deformation and to enhance the life of mandrel during manufacturing seamless steel tubes, which is able to increase the life of mandrel.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 : Shows the layout of mandrel on heating grid frame.
Fig. 2: Shows water cooling system deployed for cooling the mandrel head.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Mandrels which are ready for the pushing process are kept in the heating grid frame (6) as shown in the figure 1. Mandrels (3) with the stepped head (9) are arranged over the rails (5) in sequence. Heating grid frame can hold a maximum of fourteen mandrels during the pushing process.
The cooling system deployed for mandrel head cooling consists of water trough (4) and water lines (1) are shown in figure 2. The cooling system is introduced in the heating grid frame (6) wherein mandrel (3) will be in waiting position after working with previous shell in very hot condition over the rails (5) ready to get inserted into hollows

for pushing process. The cooling unit consists of water trough (4) of dimension 3m x 1m x 1m placed below the mandrel head for collecting the return water after cooling the mandrel head (9) by injecting water from pipelines (1) and individual water pipelines (1) of size 20 mm for mandrel head cooling. Pipelines are connected to common header line (2) which is fixed to the heating grid frame by means of pipe clamps (7). Water collected in the trough (4) is drained out through drain pipe (8). Individual water pipelines for mandrel can be switched ON/OFF using the ball valve (10) depending on the number of mandrels used for the pushing process.
Cooling of mandrel head results in lesser wear and tear of mandrel during pushing process and hence would result in improved life of costlier alloy steel mandrel.

WE CLAIM
1. A system for cooling mandrel head before push bench mill process to prevent
deformation and to enhance the life of mandrel during manufacturing seamless steel
tubes, the said cooling system comprising;
a water trough (4) configured under a mandrel head (9) for collecting the return water after cooling the said mandrel head (9);
at least one individual water pipe line (1) for cooling the hot mandrel head (9) disposed on a heating grid frame (6) wherein the hot mandrel (9) is in a waiting position over a plurality of rails (5) for being inserted into hollows of a heated round billet for a pushing process, when the pipelines (1) are connected to a common header line (2) fixed to the heating grid frame (6) by means of pipe clamps when a drain pipe (8) is configured for draining out water collected in the trough (4) wherein a ball valve (10) is disposed for switching ON/OFF individual water pipe lines for mandrel depending on the number of mandrels (3) used for the pushing process.
2. A method for carrying the system claimed in claim 1, comprising;
placing a water trough (4) beneath the mandrel head (9);
connecting the pipelines to a common header line (2) fixed to a heating grid frame by means of pipe clamps;
a drain pipe (8) connected to the trough (4) to drain out collected water;

a ball valve (10) disposed for switching ON/OFF the pipelines (1) depending on the number of mandrels deployed for the pushing process, wherein,
a plurality of mandrel head (9) is disposed on a plurality of rails (5) fixed on the heating grid frame (6) when the said mandrel is in a waiting position to be inserted into hollows for pushing process, when the pipelines (1) inject water on the said mandrel to cool the mandrel head (9),
3. A cooling system as claimed in claim 1, wherein the heating grid frame (6) holds fourteen number of mandrels (9) during the pushing process.
4. A cooling system as claimed in claim 1, wherein the dimension of water trough (4) configured in the system is 3m x 1m x 1m and diameter of pipeline for mandrel head cooling is 20mm.