FIELD OF THE INVENTION
The present invention generally relates to Cross roll piercing and elongation units of a seamless steel tube manufacturing plant. More particularly, the present invention relates to an improved method and device for removing the diescher disc from the gearbox output shaft in Cross Roll Piercer and Elongator units of Seamless Steel Tube Manufacturing Plant.
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 involves three major metal deformation processes namely cross piercing and elongation, pushing and rolling.
Blooms manufactured through concast casting are used as raw material for making the finished tubes. These blooms are cut using a gas cutting operation into billets. These billets are then charged to a rotary hearth furnace which heats up the billets from room temperature to a temperature of 1250°C to 1300°C.

It is then the billets are taken for first major metal deformation process, known as cross-piercing and elongation. At this stage, a solid billet is converted to a hollow having a through hole. Wall thickness, outer diameter and length are controlled by adjusting the control parameters of the cross piercing and elongation unit. The desired dimensional characteristics are obtained by using a plug and adjusting gaps between at least two rollers and diescher discs of said cross piercing and elongation unit. Cross piercing and elongation process is followed by Push Bench and Stretch Reducing process.
The process of seamless steel tube manufacturing using cross piercing elongation method uses at least two rolls and two guiding disc for formation of the tubes. In this process, two numbers of rollers are driven by using induction motors which run at constant speed. Two guiding discs are rotated by a top-mounted motor which runs at variable speed based on the requirement. During the process, the hot billet from a Rotary hearth furnace coming from the roller conveyors, is pushed into the cross piercing and elongation unit using an entry pusher. The entry pusher is an arrangement for pushing the hot billet till it touches the rolls. Once the hot billet makes a contact with the roll and disc, the

formation of tubes will take place with the help of a mandrel. Diescher discs are subjected to wear during the rolling operation and the expected life of the disc is around 50,000 piercings. Diescher discs have to be replaced with a new set after its estimated life.
Diescher disc carriage gearbox assembly is shown in figure 1. Diescher disc (2) which is meant for guiding the hollow billet formed during the rolling is mounted on an output shaft (1) of the carriage gearbox (3),
Discs (2) is having outside diameter 1680 mm with height of 148 mm, and weighing about 5400 kgs fitted on said output shaft (1) having outside dia 650 mm with a gearbox (3) mounted on a traversable carriage. The practice of removing the diescher disc (2) from the gearbox output shaft (1) is by applying pulling force on the disc by an overhead crane (4) through a plurality of lifting tackles (5) as shown in figure 2. The pulling force on the disc is directly transmitted to the output shaft of the gearbox which in turn damages the oil seal of the shaft (1). This practice is very difficult and consumes tremendous time for removal of the disc. Therefore, there is a need to devise an alternate method for easy removal of diescher disc without damaging the oil seals and with safe operating conditions.

OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose an improved method and device for removing the diescher disc from the gearbox output shaft in Cross Roll Piercer and Elongator units of Seamless Steel Tube Manufacturing Plant.
Another object of the present invention is to propose an improved method and device for removing the diescher disc from the gearbox output shaft in Cross Roll Piercer and Elongator units of Seamless Steel Tube Manufacturing Plant which allows removal of diescher disc without damaging the oil seal and with significant reduction of tool change time.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved method and device for removing the diescher disc from the gearbox output shaft in Cross Roll Piercer and Elongator units of Seamless Steel Tube Manufacturing Plant, the device comprising a top frame assembly consisting of a plurality of I beams, a connecting plate (8) , and at least three equispaced holes, the method comprising the steps of fixing the device to the diescher disc by connecting at least three stud rods through

said holes placing a hydraulic cylinder between an output shaft of a gearbox of the unit and the device; exerting a pulling force on the diescher already attached to the device which in turn applying a pushing force on the output shaft and thereby directly transmitting the pulling force on the disc to the output shaft to prevent the frequent damage of the oil seal of the shaft and thereby minimizing periodical replacement of oil seal of shaft. This method required very less effort and time required is only one fourth of the existing method.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - shows a schematic diagram of a diescher disc carriage with the disc mounted on the output shaft of a diescher disc gear box.
Figure 2 - shows a conventional method of diescher disc removal arrangement using Electrically Operated Trolley crane and lifting tackles.
Figure 3 - shows a device for safely applying pulling force on the disc and pushing force on the shaft to avoid damage of oil seals.
Figure 4 - shows the details of diescher disc carriage with the device assembled on the disc and hydraulic cylinder between the device and gearbox output shaft.

DETAILED PFfirMPTION OF A PREFERPFn EMBODIMENT OF THE PRESENT INVENTION
Details of a device of the invention mainly consisting of a top frame assembly (6) in top view are shown in figure 3. Top frame assembly is a welded construction consisting of at least two numbers of I beams (7), a top connecting plate (8) and three holes (9) of a diameter of 40 mm equi-spaced at 120° apart.
Accordingly, the new device with necessary fastening arrangements are shown in Figure 4. The frame assembly (6) consisting of a plurality of I beams (7 of Figure 3) with a connecting plate (8 of figure 3) and diametrically equally spaced three holes (9 of figure 3) is fixed to the diescher disc (2) by means of three equispaced stud rods (10). A hydraulic cylinder (11) is placed between the top frame assembly (6) and the gearbox output shaft (1). By this arrangement, it is possible to exert a pulling force on diescher disc (2) which in turn exerts pushing force on the shaft (1). The vertical relative movement is constrained within the diescher disc (2) and the shaft (1) itself. Damage to the oil seal (not shown) is prevented since the pulling force is not transmitted to the gearbox. This method enables ease of disc removal and damage to shaft oil seal is prevented.

WE CLAIM:
An improved method and device for removing the diescher disc from the gearbox output shaft in Cross Roll Piercer and Elongator units of Seamless Steel Tube Manufacturing Plant, the device comprising a top frame assembly (06) consisting of a plurality of I beams (7), a connecting plate (8), and at least three equispaced holes (9), the method comprising the steps of fixing the device to the diescher disc (2) by connecting at least three stud rods (10) through said holes (9); placing a hydraulic cylinder (11) between an output shaft (1) of a gearbox (3) of the unit and the device (6); exerting a pulling force on the diescher disc (2) already attached to the device (6) which in turn applying a pushing force on the output shaft (1); and thereby directly transmitting the pulling force on the disc (2) to the output shaft (1) to prevent the frequent damage of the oil seal of the shaft (1) and thereby minimizing periodical replacement of Oil seal of shaft (1).