FIELD OF INVENTION
The present invention relates to development and manufacturing of a device for
clamping abrasive wheel of bore size 20 mm for redressing purpose as the wheel
gets worn out after grinding the HSS/Carbide cutters on Tool and Cutter Grinder
machine. More particularly it relates to development of a set of device for holding
the abrasive wheel of bore size 20 mm in a Tool and Cutter grinder machine
spindle which facilitate the redressing of worn out wheel.
BACKGROUND OF THE INVENTION
Purpose of Tool and Cutter Grinder machines are to provide re-sharpening facility
for worn out / damaged tool. These tools are used for machining the steam
turbine blades. The efficiency and accuracy of Turbine blades depends upon the
manufacturing of blades by HSS/ Carbide Tools. During machining, these tools
gets blunt and therefore need to replace these blunt tools with new/ re-
sharpened tools for further machining. These blunt tools can be used again after
re-sharpening on Tool and Cutter grinder Machine by CBN/Diamond Abrasive
Wheel. In one prior art document, the machine spindle has provision for
accommodating Abrasive Wheel of 31.75 mm bore size only and in another prior
art have the machine spindle for accommodating Abrasive wheel of 20 mm bore
size.
After re-sharpening few qty of blunt tools, these Abrasive wheels get worn out
and radius is developed at the edges which affect the quality of re-sharpening.
To avoid these poor type of re-sharpening either new wheels are required or
dressed wheel are required. New CBN/Diamond Wheels are very costly and it is
not economical to use new wheels every time.

However dressing facility is available only on a particular machine for wheel of
31.75 mm bore size for dressing whereas there is no provision for dressing the
wheel of 20 mm bore size.
OBJECTS OF THE INVENTION
1. It is therefore an object of the invention to develop a device which can clamp
the 20 mm bore size of wheel on the particular machine spindle.
2. Another object of the invention is to perform dressing of worn out wheel of 20
mm bore size on particular machine which enhances productivity and cost
saving.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1- showing the Existing spindle attachment system for clamping 31.75
mm bore size abrasive wheel.
Figure 2- Drawing of novel device showing the coupling Part -I and Part -II-
according to the invention.
Figure 3- New set up showing the clamping of abrasive wheel with bore dia 20
mm in the machine spindle in combination with coupling part I and II.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The original technology for dressing the wheel bore size 31.75 mm of abrasive
wheel was provided for the machine for a particular make only.
The dia 31.75 mm wheel coupled with attachment shown in (Fig-1) was given by
the machine supplier.

However we have Tool and Cutter Grinder of other make where abrasive wheel
of 20 mm bore size are used. After re-sharpening few cutters these wheels get
worn out and declared them as a scrap because these CBN/Diamond wheel can't
re-sharpen the HSS/ carbide tools again with better quality of cutting edges and
other important dimensions present on the tools. Initially there was limited
number of machines for blade machining where HSS/carbide tools were used.
But with increase in load, consumption of HSS/ carbide cutters have increased.
As a result of high consumption of HSS/carbide cutter, the resharpening load has
increased which has indirectly resulted wearing out of abrasive wheels at a faster
rate.
The development of the coupling device has overcome this difficulty by
facilitating easy coupling for holding 20 mm bore size abrasive wheel on the
machine for which there was no such facility available earlier.

WE CLAIM
1. A coupling device comprising:
a coupling part II which holds the abrasive wheel 20 mm dia with a shoulder
abutting one face of the wheel;
a separate coupling part I which fits inside part II where the external peripheral
surface of coupling part I interface with the internal peripheral surface of
coupling part II and the internal threading surface of coupling part I fits with the
external thread of machine spindle, the shoulder of Part I abuts the other face of
the abrasive wheel such that the wheel sits tight in between the shoulder of
coupling part I and coupling part II.
2. A method of clamping the abrasive wheel of a particular size in machine
spindle as claimed in claim 1 comprising:
- holding the abrasive wheel over coupling part II with one face of the wheel
abutting the shoulder of part II
- inserting the coupling part I inside the coupling part II whereby the outside
diameter of part I fits within the inside diameter of coupling part II and the
internal thread of part I fits over the external thread of machine spindle, the
inner shoulder of the part I abuts the other face of the abrasive wheel thus
ensuring stability to the wheel during rotation.

ABSTRACT

1. A coupling device comprising:
a coupling part II which holds the abrasive wheel 20 mm dia with a shoulder
abutting one face of the wheel;
a separate coupling part I which fits inside part II where the external peripheral
surface of coupling part I interface with the internal peripheral surface of
coupling part II and the internal threading surface of coupling part I fits with the
external thread of machine spindle, the shoulder of Part I abuts the other face of
the abrasive wheel such that the wheel sits tight in between the shoulder of
coupling part I and coupling part II.