FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patent Rules, 2003
Complete Specification
(See section 10 and rule 13)
An Automatic Drill Stopper Device And A Method Controlled Drilling
Mahindra and Mahindra Ltd.
An Indian company registered under the Indian Companies Act, 1956.
Gateway Building, Apollo Bunder, Mumbai - 400001, Maharashtra, India.
The following specification particularly describes the invention and the manner in which it is to be performed.

An Automatic Drill Stopper Device And A Method Controlled Drilling
Field of Invention:
The present invention relates to drilling of holes. In particular, the present invention relates to controlled drilling of holes whereby the depth of drilling is controlled to a desired level.
Background of Invention:
Drilling of holes is a routine and standard but essential operation in many industries. In automotive industry, the heavy parts such as an engine crankcase have specialized drilling machines for the purpose of drilling holes, which is an extensive operation in itself. As an example, in typical cast iron 4-cylinder crankcase, total numbers of holes are about 140-180. These are of various diameters and depths. In components as complex as an engine crankcase, the accuracy and precision involved in hole-drilling operation is of paramount importance. Errors in drilling operations have expensive consequences including rejection of entire parts (i.e. the engine crank case) due to even a single hole not complying with the specification.
Although many drilling operations are automated, especially in industries such as automotive, manual drilling operations or drilling which has some manual control, are still common. Operator errors in setting the drill-hole parameters and precise starting and stopping of drilling operation are not uncommon. It is not uncommon to

come across instances of an operator exceeding the depth of drilling and piercing through a hollow passage where he's supposed to drill a blind hole, for example,
Even where the depth of the drill hole is set accurately, if the drill stops operating after the set depth is reached, the part being drilled will grind against the surface of the drill holder device. This damages the surface finish and sometimes the drill jig itself (jig bush), which, after a number of drilling operations, would result in effectively altering the set depth of the drill hole. Ongoing drilling operation using such worn out part has undesirable consequences.
Hence, there is a need to provide a method or a device by which the part that comes into contact with the surface of the component that received the drill hole will stop moving relative to the surface. This will serve to reduce the wear of the part that touches the surface being drilled as well drill bushes of drill jig
These issues are faced by a wide range of industries. For example, even the hand held drills which use relatively Might' drill machines compared to the 'heavy duty' drilling machines used in manufacturing. Providing a solution to this long existing problem will therefore reduce component wastage and contribute to economy and environment.
Objects of the invention:
Accordingly, one of the objects of the present invention is to provide a device used in manual drilling operation whereby at least the part in contact with the

surface of the component receiving a drill hole stops relative motion WRT the component surface.
Another object of the present invention is to allow drilling of holes without causing surface damage to the component receiving a drilled hole.
Yet another object of the present invention is to allow manual drilling without causing wear, of the part of the drilling machine that comes in contact with the drilled-component.
Brief description of figures:
Figure 1 shows a typical drilling set up.
Figure 2 shows the components of the present invention in an exploded view
Figure 3 shows a cross section of the assembled invention
Figure 4 shows a perspective view of the assembled invention
Figures 5 and 6 show the arrangement using a quick release mechanism
Summary of the invention:
The invention incorporates a system whereby during the drilling operation the drilling force is transferred from the driver motor to the tip of the drill bit but which ensures that the drilled surface does not suffer any damage in the case the drill machine is not removed even after completion of the drill hole. Once the hole

to the set depth is drilled, the drilling machine comes in contact with the surface of the component that receives the drill hole. At this point, the present invention provides that the contact part of the drill machine stops its motion WRT the component surface while the driving motor is still connected to the driven part. However, the transfer of drilling force now takes place to the component surface rather than to the apex of the progressing drill hole.
List of parts:
Drill holder body (1) Collar (9)
Shaft (1 A) Recess (10)
Drill bit (2) Rotatable components (11)
Lock nut (3) First gap (12)
Special ring nut (4) Second gap (13)
Holder cum thrust bush (5) Spring loaded sleeve (14)
Drill stopper component (6) Ball bearings (15)
Intermediate connector (7) Slot (16)
Annular lip (8)
Description of the invention:
Figure 1 shows a typical drilling set up showing the drilling machine and the component to receive the drill holes.

Figure 2 shows the exploded view of the automatic drill stopper device of the invention. It shows a threaded drill holder body (1) with a morse taper at its one end. Inside the drill holder body (1) is a hollow morse taper socket which helps receiving and holding the drill bit (2) firmly throughout the drilling operation.
In an alternative arrangement called quick coupler arrangement, the drill holder end (the end which has the male morse taper portion) can be replaced with straight shank. The advantage of this arrangement is that it makes it possible for the whole drilling unit to be engaged with or disengaged from driver portion of the m/c spindle very quickly, resulting in large saving in operating time.
As shown in Figure 2, the drill holder body (1) has a central shaft (1A) which is threaded on the outside and which extends to a suitable length. A locking assembly, comprising a lock nut (3) and a special ring nut (4), is provided which helps fix the position of the drill holder relative to the length of the drill bit (2).
A holder cum thrust bush (5) is provided to transmit axial thrust and to allow an intermediate connector (7) to rest upon it, while performing drilling operation. The intermediate connector (7) is an annular ring provided at its one end with an annular lip (8) that protrudes on its inside. The intermediate connector (7), with the help of its protruding annular lip (8), sits over a collar (9) that is provided to the holder cum thrust bush (5).

A drill stopper component (6) is provided which serves as the component which butts against the surface which is being drilled once the required drilling depth has been achieved. The drill stopper component (6) has an annular bore througli which the drill bit (2) passes. The drill stopper component (6) is threaded externally at its one end to facilitate its connection with the intermediate connector (7). At the top surface of the drill stopper component (6) is provided at least one recess (10) arrangement in where rotatable components (11) such as spherical ball bearings or cylindrical rollers can be accommodated. The ball bearings would be able to rotate about any axis whereas the cylindrical rollers are able to roll about their own longitudinal axes. A number of recesses (10) may be provided or there may be a single continuous recess (10).
It can be observed from Figure 3 that a first gap (12) is maintained between the top surface of the intermediate connector (7) and the bottom surface of the special ring nut (4). It can also be observed that a second gap (13) is maintained between the roller bearings arid the bottom surface of the holder cum thrust bush (5).
Assembly of the invention:
Figure 4 shows a perspective view of the entire assembled invention.
The lock nut (3) is first inserted on drill holder body (1). The lock nut (3) and the drill holder body (1) together are termed as first subassembly. Next, the holder

cum thrust bush (5) is inserted through intermediate connector (7) and allowed to rest on the annular lip (8) while at the same time the special ring nut (4) is tightened over holder cum thrust "bush (5) so as to set the predetermined First gap (12) between bottom surface of the special ring nut (4) and the top surface of the intermediate connector (7) (as shown in Figures 3 and 4). The special ring nut (4), the holder cum thrust bush (5) and the intermediate connector (7) together are. termed as second subassembly.
The purpose of the lock nut (3) is simply to ensure that the special ring nut (4), and consequently the drill bit (2) assembly does not change its setting during the drilling operation. A change in setting, which can occur due to vibration, would be highly undesirable. The presence of the lock nut (3) prevents this from happening.
The drill stopper component (6) filled with the ball bearing and grease in its recess (10) is termed as third subassembly. The third subassembly is next fitted on to the second subassembly using the female threading of the intermediate connector (7) to fit in with the male threading of drill stopper component (6).
The second and the third subassemblies fitted together are termed as forth subassembly, which in turn is fitted on to the threaded shaft (1A) of the drill holder body (1) (or on to the first subassembly).

Next, the drill bit (2) is inserted in the morse taper socket of threaded shaft (1A). By loosening the lock nut (3) and rotating the special ring nut (4), the drill bit (2) depth is adjusted or set.
While the invention thus assembled is readily understood to be suitable for drilling vertically downward holes, the invention is also readily applicable in drilling vertically upward and angular holes.
Operation of the invention:
The operation of the invention will now be explained for the case of a hole that is drilled vertically downwards.
The assembled drill stopper device incorporating a drill bit (2) is attached into the drilling machine. When hanging vertically, the drill holder body (I) supports the weights of all parts, namely itself, the lock nut (3), the special ring nut (4). the holder cum thrust bush (5), the intermediate connector (7), and the drill stopper component (6). In its neutral state, the weights of the drill stopper component (6) and the intermediate connector (7) rest on the collar (9). As the drill holder body (1) rotates, the lock nut (3) and the special ring nut (4) rotate as they are directly connected to the shaft (1A). The intermediate connector (7) and the drill stopper

component (6) together rotate due to the virtue of the fact that the lip (8) rests on the collar (9).
As the drill bit (2) touches the surface requiring drilling, it, under the action of the axial thrust and the rotational energy, begins to drill. All parts of the automatic drill stopper device are rotating at this stage. However, the only part that is under axial thrust at this stage is the drill bit (2) itself.
As the drilling progresses, the drill stopper component (6) progressively nears the surface of the drilled component. As the drill bit (2) finally reaches its intended drilling depth, the drill stopper component (6) touches the surface. At this stage, as the drill bit (2) cannot progress down any further, the axial thrust in the drill bit (2) is transferred through the surface back into the drill stopper component (6). The drill stopper component (6), through the set of ball bearings, transfers the axial thrust into the holder cum thrust bush (5), which in turn transfers the axial thrust back into the shaft (1A) of the drill holder body (1).
As the surface is stationary, the drill stopper, under the action of the axial force stops its own rotational motion. The axial force also pushes the drill stopper component (6), and along with it the roller bearings, upwards. The roller bearings now come in contact with the lower surface of the holder cum thrust bush (5). Through this contact, the rotational energy of the drill machine is transferred to

the roller bearings which, rotate in their respective recesses (10), while allowing the drill stopper component (6) to remain stationary under the axial load.
In an embodiment of the invention (see Figures 5 and 6), an alternative arrangement to secure the the automatic drill stopper device into a drilling machine is provided. This attachment uses a release mechanism using a spring loaded sleeve (14), ball bearings (15) and slots (16). A slot is provided on the shaft (1A) into which a ball resides and is restricted by a spring loaded sleeve. Upon release of the ball by movement of the sleeve, the entire drill stopper is removed. This avoids the action of release of the drill stopper from the main spindle with the help of a tapping pin, thereby adding safety and efficiency to the drill bit (2) release and change operation.
As Figure 5 shows, the lock nut (3) and the special ring nut (4) may be reduced in size to reduce overall weight of the drill stopper device making it more economical to produce and easier and safer to handle.
The advantage of the present invention is that even though the m/c spindle is rotating & driving the drill bit (2), the depth of the drilled hole in component does not extend beyond what has been set at the beginning.
A further advantage of the present invention is that although the drill stopper component (6) touches the surface of component or drill bush of drill jig, there is

no relative motion between two, thus protecting the surface of component from damage or wear.
A still further advantage of the present invention is that the weight of the present invention is substantially reduced with the use of lightweight materials.
It is evident from the foregoing discussion that the present invention has the following embodiments.
1. An automatic drill stopping device provided in a drill machine, characterized in that said drill stopping device has a contact part which, when it comes in contact with the surface in which a hole is being drilled by the drilling machine, stops its relative rotational motion with respect to said surface.
2. An automatic drill stopping device as described in embodiment 1 wherein said device comprises four subassemblies, namely a first subassembly, a second subassembly, a third subassembly and a fourth subassembly, characterized in that,
a. a lock nut and a threaded drill holder body together are termed as first subassembly, wherein said drill holder body has a first arrangement with which it is securely attached to the drilling machine, and a central shaft which is threaded on the outside and which extends to a first length,

b. a special ring nut, a holder cum thrust bush and an intermediate
connector together are termed as second subassembly, wherein said
intermediate connector, with the help of its annular internally
protruding lip, sits over said collar (9) provided on holder cum thrust
bush, such that a first gap is maintained between the top surface of the
intermediate connector and the bottom surface of the special ring nut,
and
c. a third subassembly comprises a drill stopper component with an
annular bore through which a drill bit passes, and wherein at the top
surface of the drill stopper component is provided at least one recess
arrangement in where rotatable components such as spherical ball
bearings or cylindrical rollers can be accommodated;
d. said second and third subassemblies are connected together threading
said intermediate connector onto said drill stopper component, to form
said fourth subassembly, such that a second gap is maintained between
the roller bearings and the bottom surface of the holder cum thrust
bush,
wherein, said fourth subassembly is adjusted over said shaft such that said lock nut and said special ring nut together help lock the drill bit in position along said shaft. 3, An automatic drill stopping device provided in a drill machine as described in embodiments 1 and 2, wherein said drill machine is any

machine selected from a group comprising hand held drilling machines, mobile drilling machines or fixed drilling machines.
4. A method of controlled drilling to a desired depth, said method comprises
the steps of:
- providing a drill stopper device as described in any of embodiments 1 to 3,
- inserting a drill bit through said annular bore and through said hollow morse taper socket, adjusting the drill length of said drill bit by adjusting said locknut and said fourth subassembly together into a locking position,
- drilling a hole into a stationary part under the action of an axial thrust and rotary motion of said drill bit,
upon said drill stopper component touching the surface of the part into which a hole is being drilled, automatic removal of axial thrust in the drill bit,
whereby said hole is drilled to a required depth without causing damage to said surface.
5. A method of controlled drilling as described in embodiment 4 wherein said holes are drilled in vertical, horizontal or any other direction.
6. A method of controlled drilling as described in embodiments 4 and 5, wherein instead of said part being stationary, the drill bit remains stationary and said part exerts rotational motion and axial thrust.

7. An automatic drill stopping device provided in a drill machine as described in embodiments 2 and 3, wherein said first arrangement comprises a morse taper at its one end, a hollow morse taper socket on the inside.
8. An automatic drill stopping device provided in a drill machine as described in embodiments 2 and 3, wherein said first arrangement is a quick release arrangement comprising a spring loaded sleeve, a set of balls, and a set of sockets, wherein when said spring loaded sleeve is slid over the sockets with the balls residing within the space between the sockets and the internal surface of said sleeve, the drill stopper device is attached securely to the drill machine, and the drill stopper is release by the movement of said sleeve by which the balls move out freely out of the sockets.
9. A method of controlled drilling as described in embodiment 6, wherein said first arrangement comprises a morse taper at its one end, a hollow morse taper socket on the inside.
10. A method of controlled drilling as described in embodiment 9, wherein said first arrangement is a quick release arrangement comprising a spring loaded sleeve, a set of balls, and a set of sockets, wherein when said spring loaded sleeve is slid over the sockets with the balls residing within the space between the sockets and the internal surface of said sleeve, the drill stopper device is attached securely to the drill machine, and the drill

stopper is release by the movement of said sleeve by which the balls move out freely out of the sockets.
While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

We claim:
1. An automatic drill stopping device provided in a drill machine, characterized in that said drill stopping device has a contact part which, when it comes in contact with the surface in which a hole is being drilled by the drilling machine, stops its relative rotational motion with respect to' said surface.
2. An automatic drill stopping device as claimed in claim 1 wherein said device comprises four subassemblies, namely a first subassembly, a second subassembly, a third subassembly and a fourth subassembly, characterized in that,
e. a lock nut (3) and a threaded drill holder body (1) together are termed
as first subassembly, wherein said drill holder body has a first
arrangement with which it is securely attached to the drilling machine,
and a central shaft (1A) which is threaded on the outside and which
extends to a first length,
f. a special ring nut, a holder cum thrust bush and an intermediate
connector together are termed as second subassembly, wherein said
intermediate connector, with the help of its annular internally
protruding lip, sits over said collar (9) provided on holder cum thrust
bush, such that a first gap is maintained between the top surface of the
intermediate connector and the bottom surface of the special ring nut
and

g. a third subassembly comprises a drill stopper component with an annular bore through which a drill bit passes, and wherein at the top surface of the drill stopper component is provided at least one recess arrangement in where rotatable components such as spherical ball bearings or cylindrical rollers can be accommodated;
h. said second and third subassemblies are connected together threading said intermediate connector onto said drill stopper component, to form said fourth subassembly, such that a second gap is maintained between the roller bearings and the bottom surface of the holder cum thrust bush,
wherein, said fourth subassembly is adjusted over said shaft such that said
lock nut and said special ring nut together help lock the drill bit in position
along said shaft.
3. An automatic drill stopping device provided in a drill machine as claimed in claims 1 to 2. wherein said drill machine is any machine selected from a group comprising hand held drilling machines, mobile drilling machines or fixed drilling machines.
4. A method of controlled drilling to a desired depth, said method comprises the steps of:
providing a drill stopper device as claimed in any of claims 1 to 3,
inserting a drill bit through said annular bore and through said hollow morse taper socket, adjusting the drill length of said drill bit by

adjusting said locknut and said fourth subassembly together into a locking position,
- drilling a hole into a stationary part under the action of an axial thrust and rotary motion of said drill bit,
- upon said drill stopper component touching the surface of the part into which a hole is being drilled, automatic removal of axial thrust in the drill bit,
whereby said hole is drilled to a required depth without causing damage to said surface.
5. A method of controlled drilling as claimed in claim 4 wherein said holes are drilled in vertical, horizontal or any other direction.
6. A method of controlled drilling as claimed in claims 4 and 5, wherein instead of said part being stationary, the drill bit remains stationary and said part exerts rotational motion and axial thrust.
7. An automatic drill stopping device provided in a drill machine as claimed in claims 2 and 3, wherein said first arrangement comprises a morse taper at its one end, a hollow morse taper socket on the inside.
8. An automatic drill stopping device provided in a drill machine as claimed in claims 2 and 3, wherein said first arrangement is a quick release arrangement comprising a spring loaded sleeve, a set of balls, and a set of sockets, wherein when said spring loaded sleeve is slid over the sockets with the balls residing within the space between the sockets and the

internal surface of said sleeve, the drill stopper device is attached securely to the drill machine, and the drill stopper is release by the movement of said sleeve by which the balls move out freely out of the sockets.
9. A method of controlled drilling as claimed in claim 6, wherein said first arrangement comprises a morse taper at its one end, a hollow morse taper socket on the inside.
10. A method of controlled drilling as claimed in claim 9, wherein said first arrangement is a quick release arrangement comprising a spring loaded sleeve, a set of balls, and a set of sockets, wherein when said spring loaded sleeve is slid over the sockets with the balls residing within the space between the sockets and the internal surface of said sleeve, the drill stopper device is attached securely to the drill machine, and the drill stopper is release by the movement of said sleeve by which the balls move out freely out of the sockets.