FIELD OF INVENTION:
The present invention relates to a Cassette type tool holder for machining valve
cones profile on a vertical boring machine.
The present invention relates to the indigenous development of a special tool
holder, using a long cassette to increase the length of tool without any vibration for
machining valve cones with conical profile on a vertical boring machine which results
in distinct advantages over conventional clamping procedure in respect of set up time,
and quality of products machined. The cassette type tool holder has been designed to
be used in a vertical boring machine for cylindrical jobs.
BACKGROUND OF THE INVENTION:
Valve cones with conical profile are regularly machined on vertical boring
machines. In order to machine the conical profile each time a long tool is required to
be clamped in such a way that while machining it should not touch the conical surface
and also it should not generate vibration. There is no provision on the machine to
clamp the long tool rigidly which can avoid vibration and also avoids collision with
ram. Thus it becomes very difficult to machine the conical profile of Valve-Cones as
well as similar profile which need long tool overhang and good surface finish. This
invention relates to designing of a cassette type tool holder for the machine which is
compatible with clamping arrangement of the ram of the machine.

OBJECTS OF THE INVENTION:
Therefore, it is an object of the invention to propose a Cassette type tool
holder for machining valve cones profile on a vertical boring machine which facilitates
employment of cassette type tool holder for different operation clamping different
type of tool and cassette in the same holder and thus to reduce machining time and
machining cost.
Another object of the invention is to propose a Cassette type tool holder for
machining valve cones profile on a vertical boring machine which is capable of
providing rigidity of tool clamping resulting better surface finish improving quality of
the job.
A further object of the invention is to propose a Cassette type tool holder for
machining valve cones profile on a vertical boring machine which is capable of
providing a special arrangement for machining internal and external profile with the
same holder.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS:
Fig. 1 : Shows the component to be manufactured.
Fig. 2 : Shows the present methodology and its constraints.
Fig. 3 : Shows high finish bore in the job.
Fig. 4 : Shows the side view of the tool holder as per prior art.
Fig. 5 : Shows the tool holder with the tool as per prior art.
Fig. 6 : Shows developed methodology with new Tool holder and Cassette.

Fig. 7a : Shows newly designed tool holder according to invention.
Fig. 7b : Shows a side view of cassette for new tool holder according to the
invention.
Fig; 7c : Shows cassette for holding tool according to the invention.
Fig. 7d : Shows new holder and cassette assembly according to the
invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION:
EXISTING METHODOLOGY:
Fig.l shows the component to be manufactured called 'Valve Cone'. This
component forms an integral part of valve cover assembly in steam turbine. The
component has a conical profile (D) at the top on outer dia. This conical profile (D) is
machined. As shown in Fig.2, in the present method the tool (T) having a length TL
emerging out of the holder is to machine the conical profile (O) for which TL is to be
greater than the length 'X' in order to avoid collision of the tool holder (H) or ram with
the job. Because of this extra extension of the length of the tool while machining at
lower end of the taper, it gives chattering on the surface and thereafter it becomes
almost impossible to machine the taper. Cuts at very low feed and speed are then
implemented to minimize the chattering on the surface, but still chattering cannot be
avoided.
To prevent the collision of the tool (T) holder (H) with the workpiece the
extended iength (TL) of the tool (T) is to be greater than X. To satisfy this constraint
tool is taken out from the holder more than the allowed length. This reduces the
rigidity of the tool because of the excess overhang and that results vibration of the
tool during machining producing chattering mark on the surface. As shown in fig. 4
and 5 the slot provided in the tool holder can only hold tool of shank size 32x32 mm.
Also, if a long tool is to be held in this holder it generates vibration in the job. Also for
machining internal and external profile machining different holder is used.

DEVELOPED AND IMPROVED METHODOLOGY:
In the Developed method the tool holder (3) has been modified in such a way
that it can accommodate a sturdy cassette (2) which in turn will hold the tool (1). This
reduces the working length of the tool and gives rigidity to the holding.
Also the length of the tool (1) and cassette (2) is adjustable which gives the
flexibility of varying tool lengths for different job. Also the cassette (2) can be
changed easily for any tool change. No need of changing the holder (3) for any tool
change. This developed method provides the arrangement for machining internal and
external profile with the same holder.
Fig. 6 and 7(d) shows the tool holder (3) holding the required cassette (2)
which holds the required tool for machining.
The cassette (2) is assembled in the tool holder (3) by taper nuts and screws.
The tool is fixed in the cassette by M10 screws. The length of the tool can be
adjusted inside the cassette while the extension of the cassette can also be adjusted
inside the slot of the holder.
The above arrangement has resulted an improved surface finish of the job
without any chattering marks when the machining time is also reduced as the
machining with developed method allows the tool to work in high feed and rpm.


BENEFITS ACCRUED:
The following are the benefits accrued after changing the process of machining
and the use of an improved tool.
1. Productivity: Total machining time of valve cone including tool changing
time on CNC VB reduced by nearly 21% (from 12hrs to 9.5hrs).
2. Financial Benefit: As cycle time is reduced critical CNC machine availability is
increased to take up more nos. of components.

3. Power Saving: Overall Productivity & Utilization of machine is increased
hence power consumption per component was reduced.
4. Quality: With use of improved process and tools, quality of
machining is also improved.
5. Health and working condition: As frequency of clamping and unclamping was
reduced so easier and safer for operators.
6. Financial Saving:
Time saved in machining of valve cone = 2hrs.
Time saved in tool changing = 0.5hrs.
Machining Cost = Rs. 4000 per hour
Total saving = 4000x2.5 = Rs. 10,000.
Average No. of valve cones per year =25
Total saving per year = Rs.2.5 Lac
7. Advantage of using the new process and improved tool from safety and
working condition point of view.
i) Tool Safety: Less tool breakages as working length is optimum which does not put
any high stress on the tool.
ii) Personal Safety: Frequent handling of tool is reduced. Tool change has become
simplified since now there is no peed of changing the entire holder.

WE CLAIM
1. Cassette type tool holder for machining valve cones profile on a vertical boring
machine comprising;
a tool holder (3) for holding a cassette;
a cassette (2) for holding a tool;
a tool (1) fixed in the cassette (2) for machining;
characterized in that,
the tool (1) in the cassette (2) and the cassette in the tool holder (3) is
adjustable length wise suiting the requirement of the machining and is operable to
machine the valve cone profile (D) without vibration and without creating any chatter
marks on the surface of the job.
2. The cassette type tool holder as claimed in claim 1, wherein the tool (1) is fixed
in the cassette (2) by M10 screws.
3. The cassette type tool holder as claimed in claim 1, wherein the cassette (2) is
held in the tool holder (3) by taper nuts and screws.
4. The cassette type tool holder as claimed in claim 1, wherein the cassette (2)
can be changed for any tool change for any different operation without changing the
tool holder.

ABSTRACT

A cassette type tool holder for machining valve cones profile on a vertical
boring machine comprises of a tool holder (3) for holding a cassette which can hold a
tool for machining the profile, the arrangement being introduced to reduce the
working length of the tool and providing rigidity of the holding. The length of the tool
(1) and cassette (2) is adjustable suiting the requirement of the machining. For
different operation, there is no need of changing the tool holder (3). Cassette (2) can
be changed for any tool (1) change without changing the tool holder (3).