FIELD OF THE INVENTION

This invention relates to the method of manufacturing of seamless steel tubes.
More particularly the invention relates to a device for lubricating an annular
space between a mandrel and a hollow billet during the manufacturing processes
of seamless steel tubes.
BACKGROUND OF THE INVENTION:
During manufacturing of seamless steel tubes there are several stages starting
from billet entry into the rotary hearth furnace to cutting the tubes to the
required length. The hollow billet formed during the process of manufacturing
steps needs to be inserted on a mandrel for further size reduction of the hollow
billet, the mandrel is inserted in the hollow billet for crimping operation at one
end and then both the hollow billet and mandrel are pushed for size reduction.
After the size reduction the mandrel has to be withdrawn and made ready for the
next operation. During the step of pushing of the mandrel most of the times, the
mandrel is stuck up with the hollow billet because of the absence of lubrication
between the hollow billet and mandrel. This problem further leads to more
pushing force and taking more current in the order of 6000 Amperes and forced
to shut down the plant for maintenance. Hence there is need to find out a
suitable lubrication method so as to get uninterrupted manufacturing of tubes.
According to the prior art, the liquid lubricant are sprinkled over the mandrel
before insertion which however is not effective due to the following reasons
namely, the bottom of the mandrel is not lubricated and a time lag exists
between the insertion of mandrel into the hot hollow billet and end of lubrication.

OBJECTS OF THE INVENTION:
It is therefore an object of present invention to propose a device for lubricating an
annular space between a mandrel and a hollow billet during the manufacturing
processes of seamless steel tubes.
A still further object of present invention is to propose a device for lubricating an
annular space between a mandrel and a hollow billet during the manufacturing
processes of seamless steel tubes in which the lubricant is injected through a
nozzle at high speed so as to travel a longer distance of approximately 4 meters.
SUMMARY OF THE INVENTION
Accordingly, there is provided a device for lubricating an annular space between
a mandrel and a hollow billet during the manufacturing processes of seamless
steel tubes. According to the invention, the standby motors are designed for
continuous operation. The lubricant is continuously pumped into the system by a
gear pump. As the hollow billet is placed in the crimping line feedback is
obtained from the hot metal detector which actuates the on/off solenoid valve.
Once the on/off solenoid valve actuates, the lubricant is sprayed for 0.5 seconds
into the hollow billet through a nozzle. After the lubricant is sprayed, the mandrel
enters the hollow billet and further operation is carried out. This process repeats
continuously. The nozzle is located at center of the crimping line stopper head.
The crimping line stopper head is modified by drilling two holes, one on
horizontal face and other on vertical face. On the horizontal face provision for
fixing the nozzle is provided and on the vertical face a ‘L’ fitting is provided
through which lubricant is pumped. The drilled holes form a passage inside the
stopper head for lubricant to flow from pipeline to nozzle.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1 shows the constructional features of the lubrication system in a
schematic diagram.
Figure 2 shows the nozzle used in lubrication system.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
PRESENT INVENTION
Figure 1 shows the schematic diagram of an annular space lubrication system.
The lubricant is stored in a tank (1). To isolate the tank (1) from the system a
shut off valve (2) is provided. The lubricant is continuously pumped into the
system by a first gear pump (4). A second gear pump (3) acts as stand by unit.
Lubricant is pumped through a pipeline (7). As the hollow billet (9) is placed in
the crimping line feedback is obtained from the hot metal detector which
actuates a first on/off solenoid valve (6). Once the first on/off solenoid valve (6)
actuates the lubricant is sprayed for 0.5 seconds into the hollow billet (9)
through a nozzle (8). After the lubricant is sprayed a mandrel (10) is pushed
inside the hollow billet and further operation is carried out. To prevent excess
pressure build up in the system, a second on/off solenoid valve (5) operates.
This process repeats continuously.
Figure 2 shows the nozzle (8) and its cut section.
The device for lubricating the annular space between the mandrel and hollow
billet reduces the friction between the components and thereby reduces the
pushing force . As per the invention, a lubricant is pumped from the tank (1)
through a first gear pump (4). A second gear pump (3) acts as standby. The

Shut off valve (2) can be operated for isolating the system from the tank. The
first On/ off solenoid valve (6) operates when the hollow billet (9) is placed in
the crimping line. The lubricant is pumped through the pipeline (7) and the
lubricant enter the nozzle (8) through a ‘L’ fitting provided at top of the stopper
head, and the lubricant is sprayed as the first solenoid valve (6) operates. Once
lubrication is complete, the mandrel (10) enters the hollow billet (9). The second
On/off solenoid valve (5) operates when the system pressure exceeds required
pressure, and returning the lubricant back to tank (1) when not needed.

WE CLAIM :
1. A device for lubricating an annular space between a mandrel and a hollow
billet during the manufacturing processes of seamless steel tubes,
comprising :
a tank (1) accommodating lubricant;
a pipeline (7) for transferring the lubricant from the tank (1);
a hot metal detector sensing a hollow billet (7) when placed on the
crimping line;
a first solenoid valve (6) actuates based on the feed back data from the
hot metal detector such that the lubricant is sprayed onto the hollow billet
(7) through a nozzle; and
a mandrel (10) advancing into the hollow billet (7) upon completion of
spraying of the lubricant.
2. The device as claimed in claim 1, comprising a second solenoid valve (5)
which is operated to prevent expensive pressure build-up in the device.