FIELD OF INVENTION
The present invention relates to cooling system applicable for machine tools. More particularly the present invention relates to an improved method of cooling circular metal cutting blades/saw in Automatic tube cutting and edge preparation (ATCEP) machine which consists of an air coolant mixing unit for cooling.
BACK GROUND OFTHE INVENTION
ATCEP is special purpose machine for edge preparation of tubes which are used for manufacturing of panels and coils for high pressure boiler application. The machine is designed and constructed with tube cutting (1 set) and tube edge preparation (2 sets) automatically from tube feed to disposal. The edge preparation involves cutting, facing, chamfering, boring to correct size of ID depending on job requirement. The edge preparation profile is normally to form “V” Groove and “U” Groove style for weld joint preparation.
In this, the tube cutting assembly is required for cutting/sizing the raw material tubes to required length depending on job requirement to carry out further operations in tube edge preparation units. It is designed and constructed in such a manner that it will hold the tube sizes of range of diameter [O.D] - 25 mm to 76.1 mm having wall thickness upto 15 mm for tubes thereby maintaining accuracy within specified tolerances for programmed preset cutting operation.
During edge preparationin ATCEP, a bundle tubes is loaded on the tube stock table and then single tube is to be feed on to the in feed conveyor by the kick-in device. Then required length of tube to be programmed in the operator console than the measuring carriage moves to the required length. The tube is transferred to the stopper of the tube length-measuring unit by the tube roller conveyor. After the leading end of the

tube touches the stopper of the tube length-measuring unit, the tube is clamped by the clamping device of the cutting unit then cutting will start. Oil mist cooling is there to cool the metal blade/circular saw from heating up. After completion of required edge preparations, the tube is kicked-out to the tube stock table. Once the tube is transferred out of the line, a new tube comes to the line and the same processing is repeated. ATCEP which is one of the critical machine running in 3 shifts, productivity of the machine is around 200 ends per shift, for typical Stainless Steel tubes the life of the blade is around 500 ends. Lead time to change each blade is around 15 minutes.
The Figure 1 shows the schematic arrangement of the existing coolant system in the tube cutting unit, where the coolant stored in the coolant sump (1) is pumped by coolant pump which is powered electrical motor (2). Flow in the coolant line (5) are controlled by using control valve (3) and while the pressure gauge (4) is used for checking the coolant pressure in the line. With pre-set electrical program/signals the electrical motor (2) operates and delivers the oil coolant droplets through oil mist droplet nozzle (6) for cooling the cutting circular saw/metal blade (7).
During cutting, the cutting blade has entangling of small slices of tube cut pieces/chips and their gradual accumulation in the circular blade due to oil mist cooling, which hinders smooth and sharp cutting of tubes for further processing. Further accumulation of chips leads to vibration of blades and pay way to breakage of cutting saws. This problem further leading to reduced productivity of the machine as well as life of the blades considerably. Hence there is need to find out suitable cooling method so as to avoid chips accumulation in circular saws.
PRIOR ART SEARCH
DE 10 2015 110 603 A1
When machining a stationary work piece by means of a rotating tool head attempting to minimize the risk of damaging the work piece by the chips or the removal of the chips simplify, when a chip receiver or a fixed nozzle for fluid are provided.

According to the prior art, due to oil mist cooling, only droplets of coolant is sprinkled at regular intervals which is not sufficient for cooling the circular blade and further this droplets carry away heat with the chips/metal pieces remains from the cutting the tubes over period of rotation chips builds to crack the blade itself forced to change new blades which adds overhead cost to the operational cost.
Hence the above prior art is similar but not relevant to the present invention.
OBJECTS OF THE INVENTION
The key objects of the invention are as follows
1. The object of the invention is to develop a method of pressurized venturi type cooling system for metal cutting in automatic tube cutting and edge preparation machine that carries away heat of circular saw/metal blades with entangled metal chips for smooth, vibration free and sharp tube cutting operation.
2. Another object of the invention is to develop a method of pressurized venturi type cooling system for metal cutting in automatic tube cutting and edge preparation machine by using air coolant mixture chamber.
3. A still another object of the invention is to develop a method of pressurized venturi type cooling system for metal cutting in automatic tube cutting and edge preparation machine that uses pressurized and venturi type air coolant mixing unit.
4. A further object of the invention is to develop a method of pressurized venturi type cooling system for metal cutting in automatic tube cutting and edge preparation machine which improves life of the circular blades/circular saw.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The Figure 1 shows the schematic arrangement of the existing coolant system in the tube cutting unit.
The Figure 2 shows the schematic arrangement of the present invention of improved coolant system in the tube cutting unit.
The Figure 3 shows air coolant mixing chamber sectional view of the present invention.
SUMMARY OF THE INVENTION
According to the invention, firstly, the pressurized air of around 5 bar is being applied to the small opening in the air coolant mixing chamber (dia 5 mm) and the coolant oil is connected in an opening (dia 5 mm) which is at an angle of 45 deg to the pressured air opening. Low pressure and venturi effect near the intersection of air and coolant enables forced atomization of coolant which carry away more quantum of heat generates during cutting of tubes. Further spraying of coolant also results in increased coverage of coolant area in the circular saw than droplet of oil mist cooling coverage thus ensuring sufficient cooling of metal blades. Also due to pressurised coolant flow with air removes the accumulated chips/metal pieces in the circular saw leading to enhanced blade life and thereby improving the machine availability for high productivity in the ATCEP machine. Thus the present invention eliminates above said drawbacks in oil mist cooling for smooth and sharp cutting of tubes.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THEPRESENT INVENTION
The Figure 2 shows the schematic arrangement of the present invention of improved coolant system in the tube cutting unit. Here the coolant is stored in the coolant sump (1). Filter, regulator cum lubricator (FRL) unit (8) is fixed in the air inlet to ensure

filtered, lubricated and regulated air flow in the system. Flow in the pressured airline (9) can be controlled using control valve (3) & pressure gauge (4) that is used to set & check the air pressure in the line. The pressurized air of around 5 bar is being applied to the small opening in the air coolant mixing chamber (10) of dia 5 mm and the coolant oil is connected in an opening (dia 5 mm) which is at an angle of 45 deg to the pressured air opening.
Low pressure and venturi effect near the intersection of air and coolant (in air coolant mixing chamber (10)) enables forced atomization of coolant to carry away quantum of heat generates with entangled metal chips in the circular cutting saw/metal blade (7) while tube cutting operation.
The Figure 3 shows air coolant mixing chamber (10) sectional view drawing in the present invention. Coolant line inlet (12) which is connected with coolant line (5) by threaded fittings and pressurised airline inlet (13) which is connected with pressured airline (9) by threaded fittings. Air coolant mixing chamber (10) made of teflon has a mixed air coolant outlet (11) for spraying the air coolant mixer over the cutting blade.
Over and above the circular saw/metal blade there is a detachable metal guard to protect operator from scattering metal chips generated during cutting operation.

We claim
1. A method of pressurized venturi type cooling system for metal cutting in automatic tube cutting and edge preparation machine comprising:-- storing the coolant in the coolant sump (1);
- fixing the filter, regulator cum lubricator (FRL) unit (8) in the air inlet for ensuring filtered, lubricated and regulated air flow in the system;
- controlling the flow in the pressured airline (9) using control valve (3) & pressure gauge (4) is used to set & check the air pressure in the line;
- applying the pressurized air around 5 bar to the small opening in the air coolant mixing chamber (10) of dia 5 mm where the coolant oil is connected in an opening (dia 5 mm) which is at an angle of 45 deg to the pressured air opening;

- enabling the low pressure and venturi effect near the intersection of air and coolant (in air coolant mixing chamber (10)) resulting forced atomization of coolant to carry away quantum of heat generated with entangled metal chips in the circular cutting saw/metal blade (7) during tube cutting operation;
- further spraying of coolant for effecting an increased coverage of coolant area in the circular saw/metal blades instead of droplet of oil mist cooling coverage for ensuring sufficient cooling of metal blades;
- resulting removal of the accumulated chips/metal pieces in the circular saw by pressurised coolant flow leading to enhanced blade life and thereby improving the machine availability for high productivity in the ATCEP machine.