FIELD OF INVENTION
The present invention relates to a system and a method of compressed air cooling during roughing operation on a 3-spindle 5-axis milling machine for milling of steam turbine blades.
BACKGROUND OF INVENTION
Manufacturing of blades for turbines of various ratings is done around the world at many facilities. Advance class manufacturing of these blades is done through 5-axis machines in single settings i.e. complete machining, generally milling, is done on 5-axis machines leaving behind only technological allowance which is then milled off on 4-axis horizontal machining centers. Excessive heat generation and reduced tool life during the operation thereof remains a critical issue during roughing operation. This also increases machine hold-up time as machine operators often have to wait for tools or cutters to cool down for changing inserts for the next set. Heating issues of machine spindles as generated heat transfers from tool via tool adopters to machine spindles were also been faced. This heating of machine spindles results in failure of feedback sensors of the spindles thus causing unnecessary hold-up on the machine.

OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose a system and a method of compressed air cooling during roughing operation on a 3-spindle 5-axis milling machine for milling of steam turbine blades which is capable of dissipating excessive heat generated during roughing operation.
Another object of the invention is to propose a system and a method of compressed air cooling during roughing operation on a 3-spindle 5-axis milling machine for milling of steam turbine blades which is capable of reducing the working temperature at contact point of tool and work piece.
A still another object of the invention is to propose a system and a method of compressed air cooling during roughing operation on a 3-spindle 5-axis milling machine for milling of steam turbine blades which is capable of eliminating failure of spindle feedback sensors due to excessive heating of machine spindle.
A further object of the invention is to propose a system and a method of compressed air cooling during roughing operation on a 3-spindle 5-axis milling machine for milling of steam turbine blades which is able to reduce the machine hold up time due to long insert-changeover time by providing faster cooling of the cutters.

A still further object of the invention is to propose a system and a method of compressed air cooling during roughing operation on a 3-spindle 5-axis milling machine for milling of steam turbine blades which is capable of enhancing the productivity of the machine by reducing machine hold-up time.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Fig.1 - Shows the flow chart of the arrangements done for provision of
compressed air for cooling during roughing operation on 3-spindle 5 axis machine.
Fig.2 - Shows a Gate valve.
Fig.3 - Shows two supply pipes from main source to machine spindle frame.
Fig.4 - Shows the distribution valve.
Fig.5 - Shows all the three spindles of the machine fitted in machine frame/body.
Fig.6 - Shows 12 number of nozzles fitted on 3 spindles of the machine.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Accordingly as shown in the drawings, the system is comprised of the following.

Fig.2 shows two Gate valves (2 Numbers, 1 for each supply pipe) used for controlling supply of compressed air from main source to distributing nozzles (7).
Gate valves are used for opening and closing of compressed air supply from main source to the nozzles which are used for cooling. It is operated manually i.e. it ‘TURNED ON’ while roughing operation and ‘TURNED OFF’ during finishing operations.
As shown in Fig.3, the two supply pipes (2) are at the ends fitted with two number of distribution valves (3) inside the spindle frame body (4) for supplying compressed air to 12 (6 nozzles/valve) nozzles fitted on three spindles (5) with four nozzles (7) per spindle. As shown in Fig.4 the distribution valve (3) for distribution of compressed air from main source to the nozzles fitted on machine spindles. Two such valves are used (6 nozzles/valve). The distribution valves (3) are disposed for distribution of compressed air from a single source or pipe to 12 Nozzles which are located on 3 spindles (4 on each spindle). Figure 5 shows all 3 spindles of the machine fitted in machine frame / body used for fixing spindles in their respective positions. As shown in Fig.6, 12 nozzles are fitted on 3 spindles of the machine (4 per spindle) for supply of compressed air at contact point of tool and work piece. It also shows position of cutting tools in machine spindles and w.r.t. to cooling air nozzles.
All these above parts form an assembly for the arrangement of providing compressed air cooling during 5-axis milling of steam turbine blades.

A system is established for provision of compressed air cooling during5-axis milling of steam turbine blades. For this, first of all a compressedair source (8) is selected for compressed air supply in the range of 5-7 bar through pipe.This supply pipe is fitted with a gate valve (1) for manually controlling the flow of air for cooling. When valve is turned 'ON', compressed air issupplied to working area and when it is turned 'OFF', supply ofcompressed air is stopped.
This pipe at the end is fitted with a distribution valve (3) which distributesthe air from a single source to 12 number of Nozzles (7) fitted around 3 spindles (5) of the machine (4 nozzles each / spindle). These nozzles (7) are designed in such a way that it directs a compressed air supply directly to contact area between tool and work piece where heat is generated.
This compressed air supply for cooling blows away chips accumulated on the tools as well as on the work piece. This results in higher tool life and better finishing of the job. Also when chips are taken away quickly from the contact area heat is also taken away as chips produced are also hot which reduces working ambient temperatures.
As tools (9), tool adopters (6) and spindles (5) all are metallic parts heat generated at contact point of tool and work piece got transferred to machinespindles (5) which in turn got hotter. There are a large number of feedback sensors in the machine spindles which are not designed to operate at such high temperatures. At these

higher temperatures they got damaged quickly. This invention helps to overcome this problem by reducing the working temperatures which in turn reduces the spindles working temperatures.
In roughing operation, carbide inserted tools were used which requires frequent indexing/changing of inserts. But due to higher temperatures of the tools/cutters operators have to wait for tools to cool down before indexing/changing inserts. This problem is also addressed with this invention as now tools doesn't have heat up that much.

WE CLAIM
1. A system and a method of compressed air cooling during roughing operation on a
3-spindle 5-axis milling machine for milling of steam turbine blades, the said system
comprising;
a source of air for supplying compressed air in the range of 5-7 bar;
a supply pipe (8) for carrying the air fitted with a gate valve (1) for manually controlling the flow of air for cooling;
a distribution valve (3) fitted to the said supply pipe for distributing the air from the source to a plurality of nozzles;
Characterized in that
a plurality of nozzles are disposed and fitted around three spindles with plurality of nozzles each per spindle for receiving and distributing the supplied compressed air directly to contact area between tool and workpiece for cooling the generated heat and for blowing away chips accumulated on the tools and work pieces for enhancing higher tool life and for eliminating the possibility of transfer of heat to the machine spindle for saving the feedback sensors of the machine spindle.
2. The system as claimed in claim 1, wherein number of nozzles disposed in the system
are twelve with four nozzles for each spindle.

3. A method for the compressed air cooling by the system claimed in claim 1 comprising;
arranging a source of compressed air
carrying the compressed air through a supply pipe fitted with a gate valve (1) to manually control the flow of compressed air for cooling;
fitting the supply pipe to a distribution valve (3) to distribute the compressed air from the source to a plurality of nozzles; wherein
the compressed air is received and distributed through a plurality of nozzles fitted around three spindles directly to the contact area between tool and workpiece to dissipitate the generated heat.


ADVANTAGES: Because of compressed air cooling, we have the following advantages:
1. Increased (nearly doubled) working life of tool during initial roughing operation of steam turbine blades with this setup
2. Less working temperatures at point of contact of tool and work piece i.e. less temperatures of working machine spindles i.e. proper functioning of machines sensors.
3. Reduced machine hold-up time of machine due to sensors feedback problem.
4. Less tooling time or inserts changeover time as a low ambient temperature keeps tools cool which reduces operators waiting time before insert change
5. All above factors culminate in increased productivity of the 3-spindle 5-axis machines.