FIELD OF INVENTION
The present invention relates to an improved boring bar for holding standard productive cutting heads as well as conventional tools with provision for internal coolant now. More particularly, the invention relates to an improved boring bar with provisions for serration on the face of the boring bar for a rigid coupling with a cutting head for vibration free machining.
This developed versatile boring bar is capable of using latest productive cutting heads with indexable carbide insert for boring operation, which has provision for internal coolant supply through boring bar for trouble free machining. These features enhance capability, productivity and performance of boring bar maintaining its old foreseen application using conventional tool. As the same boring bar has a rectangular slot also which can hold conventional turning tool/insert which is required for special turning/grooving operations for which no standard cutting heads are available in the market.

This results in distinct advantage as the same boring bar is being used for the productive standard cutting heads as well as for special conventional turning/grooving tools.
The developed boring bar can be used in all the horizontal lathes, boring machines universally.
BACKGROUND OF THE INVENTION
Latest Standard Boring Bars & Cutting Heads:
The cutting head as shown in Fig. 1 and 2 is a standard item generally available with tool manufactures. Boring Bar, as per requirement with matching cutting heads need to be procured for meeting machining requirements. This can carry machining at very high cutting parameters on a Horizontal Lathe. The head can be mounted on the boring bar equipped with provision of internal coolant and serrations.
These latest tools can be used at a cutting speed of 80-140mm/min and feed upto 0.2-0.5 mm/rev resulting in much faster machining.

Old Conventional Boring Bar with special Tools:
Conventional boring bars (2C) have a rectangular slot (4) as shown in the figure 3. The conventional tool is fixed in this slot (4) with the help of two studs (5) at the face. This arrangement is not able to give the sturdy clamping to the tools as not the complete area of the tool is pushed by the stud (5). This arrangement makes it difficult to achieve the quality surface finish.
Also special care needs to be takes for the length X as shown in figure, because gap more than this length needs to be left at end of boring to avoid collision.
There is no provision of internal coolant in this old conventional boring bars (2C).
These conventional tools run at much lower parameters of cutting speed 40-60mm/min and feed upto 0.1-0.3 mm/rev resulting in much faster machining.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose an improved boring bar for holding standard productive cutting heads as well as conventional tools with provision

for internal coolant flow, which enables mounting of productive standard cutting head capable of using high cutting parameters thereby reducing machining cycle time, tool consumption and improved surface finish.
Another object of the invention is to propose an improved boring bar for holding standard productive cutting heads as well as conventional tools with provision for internal coolant flow, which can provide a universal type arrangement for all Lathes and boring machines having similar provision for tool holding for machining of complicated turning contours where multiple type of tools are required.
A still further object of the invention is to propose an improved boring bar for holding standard productive cutting heads as well as conventional tools with provision for internal coolant flow, which is capable of reducing the machining and tooling costs by using developed special boring bar with different type of standard as well as special production turning/grooving tools and cutting heads in the same boring bar as per requirement.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: Shows productive standard cutting Head.
Figure 2: Shows productive standard cutting Head in Assembly.

Figure 3: Shows conventional boring bar according to prior Art.
Figure 4: Shows an improved boring bar having advantage of using new cutting heads as well as old conventional tools according to the invention.
Figure 5: Shows a conventional boring bar with a turning tool,
Figure 6: Shows a boring bar with serration on the face of the conventional boring bar.
Figure 6a: Shows a face grooving head.
Figure 6b: Shows a turning head,
Figure 6c: Shows flow of internal coolant.
Figure 7: Shows coolant flow development in the conventional boring bar.
Figure 8: Shows an improved bar with a conventional grooving tool.
Figure 9: Shows a complete boring bar according to invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
The details of the present invention have been explained through following
points.
1. Old methodology.
2. Developed methodology.
3. Advantages of the Developed methodology.
Old Methodology
In the old method standard boring bars (2C) of conventional design having provision for clamping of square shank (θDXθD) tools are used.
These tools work only at very low cutting parameters and it is difficult to achieve high accuracies due to vibrations at longer overhang of boring bar (2C) and also due to low performing old design boring bar (9).
There is no provision of internal coolant which increases tool wear during boring specifically at longer depths where chip evacuation also becomes a problem.

Also there is limitation that cutting point can´t reach upto deepest point due to Dart of boring bar protruded ahead of cutting tool (9).
Developed boring bar for developed methodology
There were only two options for switching to new production technology. One of the options was to procure new boring bar with matching cutting heads from tool manufacturer or other option was to innovate and design/develop boring bar in-house having technical advantages, capability to use latest cutting heads and user friendly design.
New drawings of the boring bar (2) were developed with required serrations (7) to match with the serrations (1) of the cutting head (3).
Design of special boring bar (2) having provision at one end to match with existing machine holding mechanism and another end to match with new cutting head was envisaged and developed.
Complete new drawing and 3D model was generated checking all possible limitations.

Development of serrations has helped in mounting of different types of productive heads on Conventional Boring Bars. The heads as shown in fig. 6a, 6b and 6c can be mounted on the same boring bar for different types of turning operations like grooving, facing, face grooving etc.
Provision of internal coolant flow was also made in the conventional boring bar. To make this provision as shown in fig.7 a drill was made in the center of the boring bar. A center drill of length L1 was made. This drill was shifted by a distance X and again a drill of length L2 was made in the boring bar.
LI, L2 and X will depend on the dia of the boring bar and dia of the productive boring bar head to be used with this boring bar. Drill of center drill will depend on the dia of nozzle available on the existing machine for external pipe which will rush the coolant into the boring bar. The center drill is shifted by a distance X so that the coolant passes through center of cutting head. The boring bar (2) so developed can now hold different type of cutting heads like grooving, turning tools of different angles.
Rectangular slot of conventional boring bar:
It is required to get advantages of conventional boring bar because for use with special square shank tools (Brazed or HSS) for which standard cutting heads are not

available in the market. As is dearly demonstrated in fig. 8, a grooving tool (10) can be used for making deep grooves in cylindrical jobs.
DEVELOPMENT OF NEW BORING BAR HAVING ADVANTAGES OF BOTH BUT AT LOWER COST
The developed boring bar utilizes the advantages of both types of tool. New cutting heads as well as old conventional tools can be used with this developed boring bar (2). Also a provision of internal coolant (6) was made in the boring bar (2) so as to increase its productivity. Serrations (7) were also made to hold productive cutting head (3). This has resulted in high cutting parameters being realized on developed boring bar and also the flexibility to use special conventional tools.
The improved boring bar is a cylindrically round bar and made of mild steel, carburized and hardened to RC 60. The hardened bar is ground to the specific dimensions required where ̀d1´ is 80 mm, ̀d2´ is 100 mm, `A´is 400 mm, `B´ is 150 mm. The drilled hole for internal coolant flow is made for a length of L1 equal to 600 mm and drilled for a length of L2 equal to 150 mm.

The following are the benefits accrued after use of developed technology.
1. Development of new design boring bar having advantages of both conventional as well as latest productive boring bar.

2. Capability Enhancement: Capability of old conventional boring bare enhanced at low cost.
3. Productivity: Total machining time of different jobs on Horizontal Lathe is reduced.

4. Quality: By using above mentioned boring bars, required drawing accuracies and surface finish are achieved that's why quality of machined component is improved.
5. Financial Benefit: As cycle time is reduced critical CNC machine availability is increased to take up more nos. of components.

6. Power Saving: Overall Productivity and Utilization of machine is increased hence power consumption is reduced.
7. Health and working condition: As clamping and unclamping is reduced, so machine operators will face less fatigue.

8. Financial Saving:
Cost of new boring bar = 5.66 Lacs (of Length=1100MM and θ1OOMM)
Saving against cost of new procurement which could be avoided by new
development, considering requirement of 5 Boring bar/year
Total time saved/component (i.e. valve cover) = 20 hours
Machining Cost = Rs.3000 per hour.
Total saving/component = 3000 x 20 = Rs. 60000 = 0.6 Lacs
No. of components in a year = 20
Total saving per year = 5 x 5.66 + 20 x 0.6 Lacs = Rs. 40.3 Lacs
9. Tool Safety: Less tool breakages due to vibration free boring.
10. Personal Safety: Frequent handling of tool is reduced. Tool change has become simplified since now there is no need of changing the entire holder.

WE CLAIM
1. An improved boring bar for holding standard productive cutting heads as well as conventional tools with provision for internal coolant flow, the said improved boring bar
comprising;
a cylindrically round bar, of diameter d1 mm for a length of `A´ mm and tapered to a diameter of d2 mm for a length of `B´ mm, the said taper matching the taper of the machine spindle for correct fixing of the boring bar (2);
a rectangular slot (8) configured in the front part of a boring bar for holding a turning (10) or grooving tool or insert for turning or grooving operations;
characterized in that,
a provision for internal coolant flow is made along the length of the boring bar at the center by a drill for a length of L1 mm and shifted radially for a distance `X´ mm and drilled for a length of `L2´ mm and providing a passage for coolant flow for trouble
free machining,
wherein a serration (7) is made on the face of the boring bar (2) for a rigid coupling between the boring bar and standard cutting head for vibration free machining.
2. The improved boring bar as claimed in claim 1, wherein the boring bar is made of mild steel, carburised and hardened to rockwell hardness Rc-60 and ground to the

dimension of d1 equal to 80 mm and tapered ground to d2 equal to 100 mm for matching machine holding mechanism.
3. The improved boring bar as claimed in claim 1, wherein the length `A´ is equal to 400 mm, length `B´ is equal to 150 mm.
4. The improved boring bar as claimed in claim 1, wherein the drilled length L1 is equal to 600 mm and L2 equal to 150 mm.
5. An improved boring bar (2) as claimed in claim 1, wherein the said boring bar is workable at a cutting speed 80-140 mm/min and with a feed upto 0.2-0.5 mm for achieving faster machining.