FORM-2
THE PATENTS ACT, 1970
(39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
SYSTEM FOR HIGH ACCURACY CHANGEOVER IN THE POSITION OF THE COMPONENT TO BE MACHINED
Applicant:
MAHINDRA & MAHINDRA LIMITED
GATEWAY BUILDING, APOLLO BUNDER,
MUMBAI - 400001,
MAHARASHTRA, INDIA.
Inventor:
Shankar P. Mahanta
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE USED.

FIELD OF THE INVENTION
The present invention relates to a system for positioning of jobs on work tables or machines in any manufacturing unit, particularly the invention relates to precisely locating the jobs during machining, more particularly the invention relates to a system for high accuracy changeover in the position of the components to be machined.
BACKGROUND OF THE INVENTION
Normally, locating pins are used for precisely controlling the positioning of a work piece on the machines in any tool room or manufacturing plant. The component needs to be located and kept in a precise position and/or orientation in the jig or fixture for accomplishing an accurate machining. Therefore, the jig or fixture also has to be correctly located and fixed with reference to the cutting tool and machine tool. It is also to be ensured that the component shall not move at all after fixing or clamping in its appropriate position or orientation. Figure 1 shows the possible twelve degrees of freedom in a solid body, which need to be arrested by suitable means to be accurately located, supported and clamped as shown in Figure 2.
According to the teachings of the lesson 33 on "Purposes of jigs and fixtures and their design principle", Version 2, ME, IIT Kharagpur under chapter (iv) "Principles and methods of locating, supporting and clamping blanks and tool guidance in jigs and fixtures" (kindly also refer to relevant Figures 1-4 and 5-6 explained in detail in the subsequent description):
- At least one, preferably machined surface and/or drilled / bored hole(s) shall be used as references
- Most important and significant features of the component, on which most of the dimensions are based, shall be used as reference surfaces.
- Locating method shall be easy, quick and precise.

- Locating pins as well as the mounting and contacting points thereof shall be sufficiently strong, rigid and hard.
- Minimum three points shall be used for locating a horizontal flat surface.
- Distance between the locating pins shall be as much as practically possible.
- Suitable V-blocks and cones shall be used for self-locating solid and cylindrical solid component.
PRIOR ART
In contrast to the lathe machine, the component is kept fixed on a flat surface, such as the machinebedror work table-ofcthe machine Jools^such as in drilling machine, boring machine, milling machine, planning machine, broaching machine and surface grinding machine. In these machine tools, fixtures are normally used and jigs are particularly used for drilling, reaming operations for batch production.
In particular, for machining these jigs and fixtures, the component is located different manners, e.g. locating by flat surfaces, wherein the component is located by using different types of flat-ended locating pins and buttons (Figure 3).
Normally, the side locking of a cylindrical pin shifts the axis of the pin by approximately 0.05 mm. The self-aligning MT / ISO / BT taper require a long length, whereas the available length was ju?t 15 mm. This has necessitated devising something different from the standard available taper, which would be also suitable from the quality aspects, e.g. Repeatability, Reliability and Reduction in time for set-up change. After each and every set-up change, the machine tool is kept idle for CMM to check the coordinates of the component. Subsequently, suitable correction is/are made as per the CMM report and only then the production can be started.

DISADVANTAGES WITH THE PRIOR ART
The modular type fixture requires change of locating pin for locating of the component as per model required by the customer. This locating pin is fixed over the tomb stone of the fixture. The locating dimension undergoes changes as per the length of the model. The bore size and the length of the locating pin are small, and thereby prevent the designer from using a self-locating type system. Moreover, the standard method available in the market is Cylindrical taper, MT taper, ISO or BT taper. But, there are always some disadvantages with each and every standard mentioned above. Conventionally, the clamping system is a single entity and a huge amount of time is required for set-up change activity during a change in type or model of the component to be machined. The conventional clamping system is a single entity and requires huge amount of time for set-up change while changing the type or model of the component to be machined. The clamping system has two different entities with a detachable collar and screw and this system is normally configured by using IS, BT or MT standards. In the conventional arrangements shown in the attachments (Figures 1, 2, 5 and 6), the locating pin locates the component.
However, in CNC machines, the locating position needs to be changed for
different models and even for different components. This requires that the
cylindrical pin to be changed for locating the component in the fixture with a
very high accuracy. However, since the diameter of the bore in the locating
base and the locating pin is to be provided with a certain clearance to enter
this bore. That is why, on changing the locating pin and tightening it in the
fixture, the co-ordinates which are otherwise precisely maintained, do not
gives the same co-ordinates, because of the clearance provided between the
locating pin and the bore in the locating base. Obviously, this leads to
geometrical inaccuracies in the components being machined. In order to
obtain the geometrical dimension of the components as per the accuracies
specified in the drawings, the machined components were checked by a 3D
. its CMM and the corrections were given in the machine for obtaining the correctly
machined components. But, this is a time consuming process prone to risks of
increased component rejections.

OBJECTS OF THE INVENTION
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:
An object of the present invention is to provide a system for high accuracy changeover in the position of the components to be machined.
Another object of the present invention is to provide a system for positioning the components, which can be used for different model or types of component without any difficulty.
Still another object of the present invention is to provide a system for positioning the components, which requires very little set-up time for change in model or types of components.
A further object of the present invention is to provide a system for positioning the components, which offers repeatability of operation with same accuracy.
A still further object of the present invention is to provide a system for positioning the components, which utilizes the technique of Single Minute Exchange of Dies (SMED) for reducing set-up time.
Another object of the present invention is to provide a system for positioning the components that reduces machine idle time.
Still further object of the present invention is to provide a system for positioning the components, which reduces Coordinate Measuring Time (CMM).
SUMMARY ORTHE INVENTION v,.
In accordance with the present invention, there is provided a system for high accuracy changeover in the position of the component to be machined by locating it in the fixture, wherein the system comprises:

(i) a locating base having an upper abutment portion; a central portion with a profiled cavity and an internally threaded seat thereunder, and a lower straight cylindrical portion extending below the central portion, the lower straight cylindrical portion configured for guiding the locating base in the respective slot provided in the tombstone of the fixture; and
(ii) a locating pin of a predetermined length and having a straight cylindrical upper portion; a flat cylindrical middle collared portion for providing abutment with the upper abutment portion of the locating base; a profiled lower portion extending below the flat cylindrical portion; and an externally threaded portion protruding below the profiled lower portion,
wherein the profiled lower portion of the locating pin is adapted to match the internal profile of the locating base cavity for accurate positioning of the locating pin in the locating base and the externally threaded portion under the profiled lower portion of the locating pin is adapted to match the internally threaded seat configured in the central portion of the locating base.
Typically, the locating base comprises:
an upper portion having a flat collar and a profiled central cavity configured therein, which extends further below;
a central portion having a top portion sloping down towards the circumference thereof, and a lower cyHnd(igal portion having the remaining part of the central profiled cavity configured therein, a central internally threaded hole extending up to a predetermined depth below the central profiled cavity; and
a straight cylindrical portion extending below the central portion and having a smaller diameter and length than the diameter and length of the central portion, the straight cylindrical portion configured for guiding the locating base in the respective slot provided in the tombstone of the fixture.

Typically, the locating pin comprises:
- a straight cylindrical upper portion having a predetermined length;
- aflat cylindrical middle portion havinga diameter greater than the diameter of the straight cylindrical upper portion and having a length smaller than the straight cylindrical portion, and configured for providing abutment with the upper collared portion of the locating base;
- a profiled lower portion extending below the flat cylindrical portion, the profiled lower portion adapted to match the internal profile of the locating base cavity for accurate positioning of the locating pin in the locating base; and
- an externally threaded extension protruding below the profiled lower portion; the externally threaded extension having a diameter smaller than the lower end of the profiled lower portion;
wherein the locating pin includes a through hole for inserting the Allen key for tightening and loosening thereof into/from the locating base and the profiled lower portion having a length and profile adapted to match the central profiled cavity of the locating base.
Typically, the internally threaded seat of the locating base includes left-handed threads and the externally threaded portion of the locating pin includes right-handed threads for a quick and secure fastening of the locating pin in the locating base.
Typically, the central portion of the locating base includes at least three
' ! .
threaded holes for securing the locating base the respective fixture.
Typically, the central portion of the locating base is configured flat on a part of the solid portion on the circumference thereof for securely locking the locating base in the respective fixture.

Typically, the central portion of the locating base includes an internally threaded hole extending below the threaded seat for securing the locating pin in the locating base by means of a long threaded differential screw.
Typically, the size of the locating pin is selected according to the size of the component to be secured on the fixture for precise machining of the component.
Typically, the repeatability and reliability of positioning the locating pin within the locating base fixed in the tombstone of the respective fixture is within approximately within 0.003 mm, preferably 0.002 mm.
Typically, the system comprises:
(a) a locating base having an upper abutment portion configured with a flat collar and a profiled cavity partially configured therein and extending further below; a central portion having a top portion sloping down towards the circumference thereof and a lower straight cylindrical portion extending below and configured with the remainder of the profiled cavity and an. internally threaded seat thereunder and an internally threaded hole extending up to a predetermined depth below the profiled cavity; and a straight cylindrical portion extending below the central portion and having a smaller diameter and length than that of the central portion;
(b) a locating pin having a straight cylindrical upper portion of a predetermined length; a flat cylindrical middle collared portion having a diameter greater than the diameter of the straight cylindrical upper portion and having a length smaller than the straight cylindrical portion; and a profiled lower portion extending below the flat cylindrical portion, and an externally threaded extension protruding below the profiled lower portion and having a diameter smaller than the lower end of the profiled lower portion;

wherein the profiled lower portion is adapted to match the internal profile of the locating base cavity for accurate positloning of the, locating pin in the locating base and the externally threaded portion under the profiled lower portion is adapted to match the internally threaded seat in :the central portion of the locating base and the locating pin includes a through hole for inserting the Allen key for tightening and loosening thereof into/from the locating base and further the profiled lower portion having a length and profile adapted to match the central profiled cavity of the locating base; and the repeatability and reliability of positioning the locating pin within the locating base fixed in the tombstone of the respective fixture is within approximately within 0.003 mm, preferably 0.002 mm.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
i
The present invention will be briefly described with reference to the accompanying drawings, wherein:
Figure 1 shows several types of locating pins for locating the components to be machined;
Figure 2 shows locating the work pieces using the flat surfaces thereof by employing different types of flat-ended locating and buttons pins as shown in Figure 1a above;
Figure 3 shows the degrees of freedom possible for a solid body;
Figure 4 shows a schematic arrangement for arresting all possible degrees of freedom of components in a fixture;
Figure 5 shows the component conventionally supported by a flat surface;
Figure 6 shows the component supported conventionally supported by the
locating pins;
Figure 7 shows the fixed locating base of the locating pin arrangement in accordance with the present invention;

Figure 8 shows the locating pin in accordance with the present invention;
Figure 9 shows the top, bottom and front view of the locating base shown in Figure 5.
Figure 10 shows the top and front view of the locating pin shown in Figure 6.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the following, the locating pin arrangement in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.
Figure 1 shows several types of locating pins for locating the components on a mounting plate 8. Here, locating pins at (i) and (ii) relate to a small head configuration and locating pins at (iii) and (iv) relate to a large head configuration thereof. At position (v), the lead feature 2 allows a smooth transition while performing a locating operation of the components 10 on the mounting plate 8. The head 4 has a clearance fit with the mounting plate 8 as well as the components 10. Here, the tolerance is a function of the desired locating accuracy. The shank 6 is press-fitted into the mounting plate 8.
Figure 2 shows locating the component 10 using the flat surfaces 12 thereof,
by employing different types of flat-ended locating pins 12 and buttons pins.

Figure 3 shows all twelve degrees of freedom possible for a solid body, four each in X, Y and Z planes. All possible degrees of freedom in the components need to be arrested for accurate machining of the components.
Figure 4 shows a schematic arrangement for arresting all possible degrees of freedom of a component 10 in a fixture 16. For this purpose, the component 10 is placed and maintained in a correct position and orientation in the jig and/or fixture 16. Similarly, the iig and/or fixture 16 is also be located and fixed with respect to the cutting tool and machine tool, so that the component does

not move at all after fixing or clamping on the jig and/or fixture. Here, the locating pins 12 locate the component in correct pp.sition and the clamping forces 14 oriented and applied on different faces of the component 10 accurately fix or clamp the component 10 in desired position on the jig and/or fixture 16.
Figure 5 shows the component 10 conventionally supported on a fixture 16 by a flat surface in a conventional manner.
Figure 6 shows the component 10 conventionally supported by a locating pin 12 on a fixture 16 using clamping forces 14.
Figure 7 shows the fixed locating base 20 of the locating pin arrangement in accordance with the present invention. It includes a left-handed threading 22 for the differential screw. The base can be fixed permanently in the tomb stone of the fixture (Figure 6), so that there is no possibility to change the coordinates thereof.
Figure 8 shows the locating pin 24 in accordance with the present invention. It also includes a right-handed threading 26 for the differential screw and hole 28 for inserting the Allen screw. The replaceable locating pin 24 is provided with a special taper 30 and its face butting with the locating base 20 ensure the repeatability of locating operation with the desired accuracy. The opposed or differential screw threading, i.e. left-handed threading 22 on the locating base 20 and right-handed threading 26 provided on the spigot formed at the rear end of the locating pin 24 ensures proper fixing or clamping of the locating pin 24 on the locating base 20 as well as accuracy every time the locating pin arrangement is used on component.
Figure 9 shows the top (A) and front (B) view of the locating base 20 shown in Figure 7. The top view (A) includes three holes 34 for tightening Allen bolts (not shown) on the fixing this base 20 in the tomb stone of the fixture. A truncated conical cavity 42 is also provided for accommodating the corresponding matching portion of 30 of the locating pin 24 (Figure 10). The

locating base 20 has a flat surface 32 on one side thereof for locking the locating base in the respective fixture. Further, the front view (B) also shows one of the three holes 34 truncated conical cavity 42 provided in the upper portion 40 of the locating base 20. The extension under this cavity 42 has left-handed internal threads to match with the corresponding external threads provided on the locating pin 24. This upper portion 40 has a partially tapered profile 36, in the center of which the locating pin 24 can be accommodated with little inaccuracy, i.e. a maximum accuracy of the order of 0.003 mm, preferably within 0.002 mm is achieved while placing the locating pin 24 in the locating base 20, which is quite good from the reliability and repeatability point
of view. The cylindrical bottom portion 38 is provided for locating the locating

base 20 in the tomb stone of the fixture.
Figure 10 shows the top (A), bottom (C) and front (B) view of the locating pin shown in Figure 6. The outer profile of the tapered portion 30 of the locating pin 24 precisely corresponds to the truncated cavity 30A to accurately locate the locating pin 24 in the locating base 20 fixed on the tomb stone of the fixture. As discussed with respect to Figures 7 and 8 above, the threads 26 provided on the lower portion of the locating pin 24 are right-handed and perfectly match the left-handed internal threads 22 provided under the truncated tapered portion 30A.
WORKING PRINCIPLE OF THE INVENTION
In accordance with the present invention, the special locating 5^ taper is configured with the face abutment and the differential screw configuration, thereby providing the option to achieve the important criteria of Repeatability and Reliability well within the specified coordinate accuracy. The Repeatability obtained is approximately within 0.003 mm when checked for about 25 times.
However, the clamping system in accordance with the present invention uses HFS Standard of taper to ensure a proper abutment of the face, which results in complete load transfer to the tombstone of the jigs/fixture. A small change in the taper angle provides a better location and reliability of operation.

The locating system in accordance with the present invention has been running at the applicant's manufacturing facilities for the last 10 months without any CMM check or any rejection due to coordinate inaccuracies. The locating pin 24 accommodated from the top within a special tapered cavity 30A in the locating base 20 and their face butting system ensures that the reliability and repeatability of locating the components is always within 0.002mm, preferably within 0.002 mm, which is considered to be very well within the desired general machining accuracy limits.
Therefore, the present invention provides a unique configuration of the locating pin, which facilitates in reducing the SET-UP time (from model to model and for one component to the other) and thus, reduces the risk factor drastically.
TECHNICAL ADVANTAGES & ECONOMIC SIGNIFICANCE
Some of the technical advantages of the proposed in accordance with the present invention are as under:
- Use of HFS Standard of taper to ensure proper locking and proper abutment of the face of the component.
- Testing has been done in house.
- Results have been positive.
- TPM Consultants from CM and JIPM have also approved this system.
- Repeatability and Reliability are well obtained within the desired coordinate accuracy
Throughout this specification the word "comprise or variations such as "comprises" or "comprising", shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression "a", "at least" or "at least one" shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.
The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. The description provided herein is purely by way of example and illustration.
Although the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.
While considerable emphasis has been placed on the specific features of the
preferred embodiment described here, it will be appreciated that many
additional features can be added and that many changes can be made in the
preferred embodiments without departing from the principles of the invention.
These and other changes in the preferred embodiment of the invention will be
apparent to those skilled in the art from the disclosure herein, whereby it is to
be distinctly understood that the foregoing descriptive matter is to be
interpreted merely as illustrative of the invention and not as a limitation.

WE CLAIM:
1. A system for high accuracy changeover in the position of the component
to be machined by locating it in the fixture, wherein said system
comprises:
(iii) a locating base having an upper abutment portion; a central portion with a profiled cavity and an internally threaded seat thereunder, and a lower straight cylindrical portion extending below said central portion, said lower straight cylindrical portion configured for guiding said locating base in the respective slot provided in the tombstone - ~ of the fixture; and
(iv) a locating pin of a predetermined length.- and having a straight
cylindrical upper portion; a flat cylindrical middle collared portion for
providing abutment with the upper abutment portion of said locating
base; a profiled lower portion extending below said flat cylindrical
portion; and an eternally threaded portion protruding below said
profiled lower portion,
wherein said profiled lower portion of said locating pin is adapted to match the internal profile of said locating base cavity for accurate positioning of said locating pin in said locating base and said externally threaded portion under said profiled lower portion of said locating pin is adapted to match said internally threaded seat configured in the central portion of said locating base.
2. System as claimed in claim 1, wherein said locating base comprises:
an upper portion having a flat collar and a profiled central cavity configured therein, which extends further below;
a central portion having a top portion sloping down towards the circumference thereof, and a lower cylindrical portion having the remaining part of said central profiled cavity configured therein, a

central internally threaded hole extending up to a predetermined depth below said central profiled cavity; and
a straight cylindrical portion extending below said central portion and having a smaller diameter and length than the diameter and length of said central portion, said straight cylindrical pprtion configured for guiding said locating base in the respective slot provided in the tombstone of the fixture.
3. A system as claimed in claim 1, wherein said locating pin comprises:
- a straight cylindrical upper portion having a predetermined length;
- a flat cylindrical middle portion haying a diameter greater than the diameter of said straight cylindrical upper portion and having a length smaller than said straight cylindrical portion, and configured for providing abutment with the upper collared portion of said locating base;
- a profiled lower portion extending below said flat cylindrical portion, said profiled lower portion adapted to match the internal profile of said locating base cavity for accurate positioning of said locating pin in said locating baseband
- an externally threaded extension protruding tbelow said profiled lower portion; said externally threaded extension having a diameter smaller than the lower end of said profiled lower portion;
wherein said locating pin includes a through hole for inserting the Allen key for tightening and loosening thereof into/from said locating base and said profiled lower portion having a length and^profile adapted to match the central profiled cavity of said locating base.
4. A system as claimed in claim 1, wherein said internally threaded seat of
said locating base includes left-handed threads and said externally
threaded portion of said locating pin includes right-handed threads for a
quick and secure fastening of said locating pin iri said locating base.

5. A system as claimed in claim 1, wherein the central portion of said locating base includes at least three threaded holes for securing said locating base the respective fixture.
6. A system as claimed in in claim 1, wherein the central portion of said locating base is configured flat on a part of the solid portion on the circumference thereof for securely locking said locating base in the respective fixture.
7. A system as claimed in in claim 1, wherein the central portion of said locating base includes an internally threaded hole extending below said threaded seat for securing said locating pin fh said locating base by means of a long threaded differential screw.
8. A system as claimed in in claim 1, wherein the size of said locating pin is selected according to the size of the component to be secured on the fixture for precise machining of said component,
9. A system as claimed in in claim 1, wherein the repeatability and reliability of positioning said locating pin within said locating base fixed in the tombstone of the respective fixture is within approximately within 0.003 mm, preferably 0.002 mm.
10. System as claimed in claim 1, wherein said system comprises:
(c) a locating base having an upper abutment portion configured with a flat collar and a profiled cavity partially configured therein and extending further below; a central portion having a top portion sloping down towards the circumference thereof and a lower straight cylindrical portion extending below and configured with the remainder of said profiled cavity and an internally threaded seat thereunder and an internally threaded hole extending up to a predetermined depth below said profiled cavity; and a straight cylindrical portion extending below said central portion and having a smaller diameter and length than that of said central portion;

(d) a locating pin having a straight cylindrical upper portion of a predetermined length; a flat cylindrical middle collared portion having a diameter greater than the diameter of said straight cylindrical upper portion and having a length smaller than said straight cylindrical portion; and a profiled lower portion extending below said flat cylindrical portion, and an externally threaded extension protruding below said profiled lower portion and having a diameter smaller than the lower end of said profiled lower portion;
wherein said profiled lower portion of the locating pin is adapted to match the internal profile of said locating base cavity for accurate positioning of said locating pin in said locating base and said externally threaded portion under said profiled lower portion of the locating pin is adapted to match said internally threaded seat configured in the central portion of said locating base and said locating pin includes a through hole for inserting the Allen key for tightening and loosening thereof into/from said locating base and further said profiled lower portion having a length and profile adapted to match the central profiled cavity of said locating base; and the repeatability and reliability of positioning said locating pin within said locating base fixed in the tombstone of the respective fixture is within approximately within 0.003 mm, preferably 0.002 mm.