CLIAMS:We Claim:
1. A process for machining of Mag-Carb refractory Bricks to produce desired shaped Mag-Carb refractory Bricks comprising
providing said Mag-Carb refractory bricks requiring desired machining;

holding said brick for machining in turning/ cutter Machine;

mounting Ceramic carbide tool for said machining/cutting operation of said bricks on said turning/ cutter Machine;

performing turning operation following desired steps involving kerosene as coolant/lubricant to work-tool interface such as to limit heating of tool to ensure smooth cutting to generate desired cut surface finish of said Mag-Carb refractory bricks.

2. A process for machining of Mag-Carb refractory Bricks as claimed in claim 1 comprising
providing said bricks having an initial dimension preferably of 250 mm × 150 mm×100 mm;

holding said brick by clamping preferably in four jaw chuck for turning on a Lathe Machine;

mounting Ceramic carbide tool for machining/cutting operation of said bricks on said lathe machine;
performing turning operation in successive steps with selective combination of machining parameters comprising speed, feed and depth of cut at each step with selective flow rate of kerosene as coolant/lubricant to work-tool interface to limit heating of tool to ensure smooth cutting to generate cylindrical cut surface in each pass to obtain finally round shape of desired diameter from said Mag-Carb refractory bricks.

3. A process as claimed in anyone of claims 1 or 2, wherein said turning operation is preferably carried out in a LB-117 HMT Lathe Machine of 10 HP rating.

4. A process as claimed in anyone of claims 1 to 3, wherein said turning operation in steps is carried out beginning with a speed of 25 to 60 preferably about 45 rpm and a feed of 0.05 mm followed by slowly increasing the speed to 65 to 75 preferably about 71, preferably about 90 and 120 to 150 preferably about 142 rpm and feeding the feed at 0.04 to 0.06 preferably about 0.05 mm.

5. A process as claimed in anyone of claims 1 to 3, wherein depth of cut in each steps was maintained at 0.05 mm.

6. A process as claimed in anyone of claims 1 to 4, wherein kerosene as coolant cum lubricant is supplied at a flow rate of 0.2 to 0.3 l/min to ensure smooth cutting operation.

7. A process as claimed in anyone of claims 1 to 5, wherein the heat generation is controlled with coolant supply to limit the maximum temperature of cutting tool to 70°C during cutting operation to avoid overheating/burning of tool.

8. A process as claimed in anyone of claims 1 to 6, which can be applied to produce conical shape or for drilling holes of various diameters on said bricks as per need.

Dated this the 22nd day of October, 2014
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

,TagSPECI:FIELD OF THE INVENTION

The present invention relates to a process for machining of Mag-Carb refractory bricks to produce desired shaped bricks. More particularly, the present invention is directed to developing a process for machining of Mag-Carb bricks to produce round samples to carry out experiments on refractory erosion or other applications where round shapes are required to be made from Mag-Carb refractory bricks. Importantly, according to the process of the present invention, rounds of 70mm diameter are made from the bricks having an initial dimension of 250 mm × 150 mm×100 mm through turning operation in lathe machine involving selective parameters, tooling and coolant. The same process can be implemented to also generate conical shape or for drilling holes of desired size to suit a variety of applications.

BACKGROUND OF THE INVENTION

Mag-Carb refractory bricks are used extensively for lining converters in BOF steel making and for lining secondary steel making ladles. They are generally used in the slag zone where the refractory erosion is more. Study of refractory wear and erosion under different types of slag is of utmost importance. In order to carry out this study, round refractory samples are required to be prepared. These samples are then dipped and rotated in molten slag for a predetermined amount of time. The samples are then taken out of the slag and their erosion and wear is measured.

These Mag- Carb refractory bricks are prepared by casting the refractory material in molds. Once the bricks are made through casting, they cannot be conventionally machined since they are very hard and brittle. There is a tendency of chipping of the refractory surface while machining. Often the tool breaks during the process of machining. There is also the problem of generation of excessive heat on the tool because of high friction.

Momber et.al (A.W. Momber, I Eush and R Kovacevic, Journal of Material Science, 31, 1996, 6485) tried to use abrasive water jets at different angles in which they used high pressure pumps (up to 350 MPs) to cut bauxite, sintered magnesia and magnesia chromite. They found that though they could cut the refractory material, the surface was rough. Freist et al. (B. Freist, H haferkamp, A Laurinat and H. Louis, Proceedings of 5th American Waterjet Conference, 1989, 191) also tried similar technique but their study was limited to milling operations only.

At present, round samples are cast in moulds separately to carry out experiments on refractory erosion. There is a limitation of preparation of round refractory samples from a lot of bricks supplied to the steel plant. In order to solve the problems of making round samples from Mag-Carb refractory bricks, trials were conducted in the central workshop of applicants’ Research and Development Centre for Iron and steel.

Attempts have been made to apply machining and in particular turning operations successfully on Mag-Carb bricks so that they would render various shapes and sizes to the refractories. These shapes can be round, conical etc. Moreover, holes of various diameters can be drilled in the refractory bricks to suit various applications. The problems relating to high hardness and brittleness of the bricks, tool breakage and heat generation during machining have been successfully traversed through various trials with alternative tools and machining parameters.

In addition to making samples, the technology is developed to be used universally where round shapes are required to be made from Mag-Carb refractory bricks.

OBJECTS OF THE INVENTION

The basic object of the present invention is directed to a process for machining of Mag-Carb refractory bricks to produce round cylindrical shape as samples to carry out experiment on refractory erosion or for various other application of such refractory materials.

A further object of the present invention is directed to a process for machining of Mag-Carb refractory bricks to produce conical shape therefrom or drilling holes as per need.

A still further object of the present invention is directed to a process for machining of Mag-Carb refractory bricks to produce round shape by involving turning operation on a lathe machine.

A still further object of the present invention is directed to a process for machining of Mag-Carb refractory bricks to selectively deploy cutting tool, machining parameters and coolant/lubricant to enable machining/turning operation on Mag-Carb refractory bricks to provide desired smooth cutting and surface finish suitable for desired application.

A still further object of the present invention is directed to a process for machining of Mag-Carb refractory bricks to enable producing rounds of any diameters from Mag-Carb Bricks.

A still further object of the present invention is directed to a process for machining of Mag-Carb refractory bricks whereby rounds produced may be used to study wear and erosion of Mag-Carb Bricks under different types of slag.

A still further object of the present invention is directed to a process for machining of Mag-Carb refractory bricks such that Mag-Carb rounds produced can be used wherever round contours are required such as for lining converters in BOF steel making and for lining secondary steel making ladles.

SUMMARY OF THE INVENTION

The basic aspect of the present invention is directed to a process for machining of Mag-Carb refractory Bricks to produce desired shaped Mag-Carb refractory Bricks comprising
providing said Mag-Carb refractory bricks requiring desired machining;

holding said brick for machining in turning Machine;

mounting Ceramic carbide tool for said machining/cutting operation of said bricks on said turning Machine;

performing turning operation following desired steps involving kerosene as coolant/lubricant to work-tool interface such as to limit heating of tool to ensure smooth cutting to generate desired cut surface finish of said Mag-Carb refractory bricks.

A further aspect of the present invention is directed to a process for machining of Mag-Carb refractory Bricks comprising
providing said bricks having an initial dimension preferably of 250 mm × 150 mm×100 mm;

holding said brick by clamping preferably in four jaw chuck for turning on a Lathe Machine;

mounting Ceramic carbide tool for machining/cutting operation of said bricks on said lathe machine;

performing turning operation in successive steps with selective combination of machining parameters comprising speed, feed and depth of cut at each step with selective flow rate of kerosene as coolant/lubricant to work-tool interface to limit heating of tool to ensure smooth cutting to generate cylindrical cut surface in each pass to obtain finally round shape of desired diameter from said Mag-Carb refractory bricks.

A still further aspect of the present invention is directed to a process, wherein said turning operation is preferably carried out in a LB-117 HMT Lathe Machine of 10 HP rating.

A still further aspect of the present invention is directed to a process, wherein said turning operation in steps is carried out beginning with a speed of 25 to 60 preferably about 45 rpm and a feed of 0.05 mm followed by slowly increasing the speed to 65 to 75 preferably about 71, 85 to 100 preferably about 90 and 120 to 150 preferably about 142 rpm and feeding the feed at 0.04 to 0.06 preferably about 0.05 mm.

Yet another aspect of the present invention is directed to a process, wherein depth of cut in each steps was maintained at 0.05 mm.

A further aspect of the present invention is directed to said process, wherein kerosene as coolant cum lubricant is supplied at a flow rate of 0.2 to 0.3 l/min to ensure smooth cutting operation.

A still further aspect of the present invention is directed to a process wherein the heat generation is controlled with coolant supply to limit the maximum temperature of cutting tool to 70°C during cutting operation to avoid overheating/burning of tool.

A still further aspect of the present invention is directed to a process which can be applied to produce conical shape or for drilling holes of various diameters on said bricks as per need.

The objects and advantages of the present invention are described hereunder in greater details with reference to the following accompanying non limiting illustrative drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

Figure 1: is the photograph of the Mag-Carb brick having an initial dimension of 250 mm × 150 mm×100 mm used for refractory lining of BOF furnace or secondary steel making ladles and used as raw material for the purpose of applying the machining/turning process according to the present invention.
Figure 2: is the photograph of the machined brick of round cylindrical shape generated by applying machining process according to the present invention from the initial brick shape as shown in Figure 1.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO ACCOMPANYING DRAWING

The present invention is directed to a process for machining of Mag-Carb refractory bricks to produce round cylindrical shape as samples to carry out experiment on refractory erosion or for various other application of such refractory bricks.

Previously, round samples are cast in moulds separately to carry out experiments on refractory erosion. There was a limitation of preparation of round refractory samples from a lot of bricks supplied to the steel plant. The Mag-Carb refractory bricks are prepared by casting the refractory material in molds. Once the bricks are made through casting, they could not be conventionally machined since they are very hard. There was a tendency of chipping of the refractory surface while machining. Often the tool breaks during the process of machining. There is also the problem of generation of excessive heat on the tool because of high friction.

In order to solve this problem of making round samples from Mag-Carb refractory bricks, a process of machining has been developed by way of the present invention for the first time. An attempt has been made to machine the bricks which had an initial dimension of 250 mm × 150 mm×100 mm. Accompanying Figure 1 shows the photograph of the Mag-Carb brick having an initial dimension of 250 mm × 150 mm×100 mm used for refractory lining of BOF furnace or secondary steel making ladles.

The machining process was standardized through a number of trials.

At the very beginning, an attempt was made to cut the Mag-Carb refractory bricks using a band saw machine. The saw blades became blunt and the bricks could not be cut. A faint impression of the blades was seen on the surface of the bricks.

The bricks were then clamped in four jaw chuck of LB-117 HMT Chamundi Lathe Machine. High speed Steel Cobalt tool bits of size 20mm square were the fixed on the tool post. The machine was rotated at 112 rpm with a feed of 0.063mm. It was observed that the tool got overheated and got burnt out after cutting the brick a little bit. Various speed-feed combinations were tried out. The combinations were 114/0.046, 90/0.05, 57/0.03 etc. The bricks could not be cut using any of this speed -feed combinations.

After trying out various tools at different speed feed combinations, finally Ceramic carbide tool was used. At the beginning speed of 45rpm was used with a feed of 0.05 mm. Speed was slowly increased to 71, 90 and 142 rpm feeding the feed at 0.05 mm. Though it was possible to cut the bricks, it was found that there were a lot of jerks in the machine and the cutting was not smooth. Various coolants/ lubricants were tried but the cutting was not smooth and the tools were still becoming hot. Finally on application of kerosene oil as a coolant/ lubricant, it was found that smooth cutting of Mag-Carb refractory bricks was possible.

Thus by applying the process according to the present invention, the Mag-Carb bricks having an initial dimension of 250 mm × 150 mm×100 mm could be successfully machined into rounds of 70mm diameter. Accompanying Figure 2 shows the photograph of the machined brick of round cylindrical shape generated by applying machining process according to the present invention. Technology of making rounds from bricks through turning operation in lathe machine was thus established. In addition to making samples, the technology may be used universally where round shapes are required to be made from Mag-Carb refractory bricks. Applying the methodology, generating conical shape and drilling of holes are also possible if needed.

It is thus possible by way of the present invention to provide a standardized process for machining of cast Mag-Carb refractory bricks to generate round shape of desired dimension to produce sample for slag erosion testing or any similar form required for lining purpose, by turning the bricks on lathe machine with selective machining parameters and selective coolant/lubricant to ensure smooth cutting while also controlling the heating/burning of cutting tool.

We Claim:
1. A process for machining of Mag-Carb refractory Bricks to produce desired shaped Mag-Carb refractory Bricks comprising
providing said Mag-Carb refractory bricks requiring desired machining;

holding said brick for machining in turning/ cutter Machine;

mounting Ceramic carbide tool for said machining/cutting operation of said bricks on said turning/ cutter Machine;

performing turning operation following desired steps involving kerosene as coolant/lubricant to work-tool interface such as to limit heating of tool to ensure smooth cutting to generate desired cut surface finish of said Mag-Carb refractory bricks.

2. A process for machining of Mag-Carb refractory Bricks as claimed in claim 1 comprising
providing said bricks having an initial dimension preferably of 250 mm × 150 mm×100 mm;

holding said brick by clamping preferably in four jaw chuck for turning on a Lathe Machine;

mounting Ceramic carbide tool for machining/cutting operation of said bricks on said lathe machine;
performing turning operation in successive steps with selective combination of machining parameters comprising speed, feed and depth of cut at each step with selective flow rate of kerosene as coolant/lubricant to work-tool interface to limit heating of tool to ensure smooth cutting to generate cylindrical cut surface in each pass to obtain finally round shape of desired diameter from said Mag-Carb refractory bricks.

3. A process as claimed in anyone of claims 1 or 2, wherein said turning operation is preferably carried out in a LB-117 HMT Lathe Machine of 10 HP rating.

4. A process as claimed in anyone of claims 1 to 3, wherein said turning operation in steps is carried out beginning with a speed of 25 to 60 preferably about 45 rpm and a feed of 0.05 mm followed by slowly increasing the speed to 65 to 75 preferably about 71, preferably about 90 and 120 to 150 preferably about 142 rpm and feeding the feed at 0.04 to 0.06 preferably about 0.05 mm.

5. A process as claimed in anyone of claims 1 to 3, wherein depth of cut in each steps was maintained at 0.05 mm.

6. A process as claimed in anyone of claims 1 to 4, wherein kerosene as coolant cum lubricant is supplied at a flow rate of 0.2 to 0.3 l/min to ensure smooth cutting operation.

7. A process as claimed in anyone of claims 1 to 5, wherein the heat generation is controlled with coolant supply to limit the maximum temperature of cutting tool to 70°C during cutting operation to avoid overheating/burning of tool.

8. A process as claimed in anyone of claims 1 to 6, which can be applied to produce conical shape or for drilling holes of various diameters on said bricks as per need.

Dated this the 22nd day of October, 2014
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

ABSTRACT

TITLE: A PROCESS FOR MACHINING OF MAG-CARB REFRACTORY BRICKS TO PRODUCE DESIRED SHAPED MAG-CARB REFRACTORY BRICKS.
The present invention relates to a process for machining of Mag-Carb refractory bricks to produce desired shaped bricks. The process according to the present invention is directed to developing machining of Mag-Carb bricks to produce round samples to carry out experiments on refractory erosion or other applications where round shapes are required to be made from Mag-Carb refractory bricks. Importantly, according to the process of the present invention, rounds of 70mm diameter of required surface finish are made from the bricks having an initial dimension of 250 mm × 150 mm×100 mm through smooth turning operation in lathe machine involving selective parameters, tooling and coolant. The same process can be implemented to also generate conical shape or drilling holes of desired size to suit a variety of applications.