FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION A SYSTEM FOR IMPROVED MACHINING FIXTURE


APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTOR
Suresh Kadam an Indian national
of TATA MOTORS LIMITEP,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in
which it is to be performed.


FIELD OF INVENTION
This invention relates to machining fixture system and more particularly it relates to improved machining fixture system for job resting confirmation on Gap milling, Drilling and tapping SPM machine while drilling, tapping and gap milling operation.
BACKGROUND OF INVENTION
Generally for machining of gearbox housing, Gap milling, drilling and tapping SPM machine is used. These machines do not have a mechanism for job resting confirmation, when job is in incorrect position no proper machining will be done. These happen when some foreign particles are on the said fixture. If Burr/metal piece is found between rest pads and gear box housing, there is chance of drill axis will be skewed due to metal chip, in turn job will be rejected.
OBJECTS OF INVENTION
Main object of this invention is to provide improved machining fixture for job resting confirmation on machine.
Another object of the present invention is to provide improved machining fixture for job resting confirmation on machine which to reduce machine accident.
Another object of the present invention is to provide improved machining fixture for job resting confirmation on machine which to reduce rejection of gearbox housing due to wrong resting of job on contact surface .
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STATEMENT OF INVENTION
Accordingly the present invention discloses, a system for improved machining fixture
comprising
fixture having at least two resting pads for resting of job;
at least two air pressure sensors;
at least one control circuit;
at least one electrical control panel and;
indicator means for indicating signal received from said air pressure sensors.
BRIEF DESCRIPTION OF DRAWINGS
In accordance to the present invention,
Figure-01 shows schematic diagram of machining fixture with metal chip in between
rest pad and object.
Figure-02 shows improved rest pad.
Figure-03 shows schematic diagram of improved machining fixture.
BRIEF DESCRIPTION OF INVENTION
Improved machining fixture comprises; Fixture housing having at least two resting pad
(1) for resting the job, At least two air pressure sensors (2) for sensing the back
pressure, Electrical control panel (3), Indicator means (4) for indicating the signal
received from said sensor.
Wherein each said resting pads having holes (5) at the centre. The said holes are
connected with pressure sensor (2) with the help of air pipeline.
The holes diameter is at least 1.2mm. Two air pressure sensors are provided therein for
sensing the back pressure. Compressed air pressure at 2 Kg/cm2 is allowed to purge on
butting places of job and said fixtures through the holes provided on centre of said
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resting pads. Job is kept on fixture and the back pressure is sensed by the said air pressure sensor.
Method of confirming job resting on fixture comprises;
• Providing holes at centre of resting pads of fixture,
• Providing at least two air pressure sensor,
• Allowing compressed air to purge on butting places of job and fixture,
• Placing the job on the fixture
• Sensing air back pressure with the help of sensor provided therein
DETAILED DESCRIPTION OF INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same,
Now referring to figure-01 to figure-04, Improved machining fixture system
comprises;
Fixture housing having at least two resting pad (1) for resting the job, At least two air
pressure sensors (2) for sensing the back pressure, Electrical control panel (3),
Indicator means (4) for indicating the signal received from said sensor.
Wherein each said resting pads having holes (5) at the centre. The said holes are
connected with pressure sensor (2) with the help of air pipeline
Wherein said resting pads having holes (5) at the centre. The said holes are connected
with pressure sensor (2) with the help of air pipeline and pneumatic fitting . Said
electrical control panel (3) comprises air pressure sensor and indication lamp (4) and
control circuit.
The holes (5) provided in the rest pad having diameter at least 1.2 mm at one end
where the job is located. Said hole (5) is thorough hole has bend at 90 degree and
threaded at other end for connecting said air pipeline say at least M5 threading. The
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said rest pads also comprise mounting holes (8) for mounting it to the fixture. Two air pressure sensors are provided on said electric control panel for sensing the back pressure. Compressed air pressure at 2 Kg/cm2 is allowed to purge on butting places of job and said fixtures through the holes provided on centre of said resting pads. When there is no gap between rest pads and job to be machined then compressed air is returned back and back pressure is sensed by the said air pressure sensor and indicator means indicate the green signal. If there is metal chip in between said resting pad and job to be machined then there will be gap formation and leakage of compressed air due to this low air pressure indicator means turns red by which users come to know there is chip present on the rest pad of fixture.
In Figure 1: AA' shows the required drill axis on component and BB" shows the skewed drill axis due to presence of metal chip between the job and the resting pad.
In accordance with the present invention, Method of confirming job resting on fixture comprises;
• Providing holes at centre of resting pads of fixture shown in figure no2 and no3 by section DD'
• Providing at least two air pressure sensor,
• Allowing compressed air to purge on butting places of job and fixture,
• Placing the job on the fixture,
• Sensing air back pressure with the help of sensor provided therein.
On Gap milling, drilling and tapping machine three operations are done with following sequence
1) Drilling (Dl) operation
2) Tapping(Tl)operation
3) Gap milling (Ml) operation
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While doing above said three operation, job' (7) is rested on said fixture and it is hydraulically clamp with cylinder (6). Said fixture of machines having rest pads on which is job is rested.
If Bun/metal piece (9) is found between said rest pads and component, then there is chance of drill axis to be skewed due to metal chip and due to faulty machining component is rejected.
Compressed air (from compressor denoted as 11 in fig nol )through airline tubes (10) at 2 to 2.2 Kg/cm2 is allowed to purge on butting places of job and fixture, through a 1.2 mm hole. Job is kept on the fixture and the back pressure is sensed by the pressure sensor.
In ideal conditions the back pressure is to be 2 Kg/cm . This means there is no gap between the job surface and fixture. Improper machining or presence of foreign object/metal chip /Burr will cause the air leakage and thus the reduction in back pressure. The same back pressure is sensed and the out put is given to electrical control panel.
The Compressed air at 2 to 2.2 Kg/cm . is allowed to purge on butting places of job and fixture, through the said holes provided at the centre of said resting pad. The job is kept on the said fixture and the back pressure is sensed by the said air pressure sensor. If burr /metal piece is found between the work piece and said rest pads then it will cause the air leakage from and thus the reduction in back pressure. Same air back pressure will be less than set pressure 1.2 Kg/cm2 , The reduction in back pressure is sensed by said air pressure sensor and said air pressure sensor will generate output signal and send it to indicator means which will indicate it by turning the lamp to Red and Machine cycle will not start.
If said job is rested on resting pad in correct position then there will be no gap between said job and said rest pads and therefore there will not be any air leakage between
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said rest pads and said job .then back pressure will be generated and it will be sensed by said air pressure sensor. It will generate output, it will turn the lamp to Green and Machine cycle will start.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.
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WE CLAIM
1. A system for improved machining fixture comprising
at least two resting pads fastened to said fixture configured for resting job; at least one air compressor;
plurality of air pipes for connecting air compressor with air sensors and further to said resting pads;
at least one electrical control panel comprising
at least one control circuit for controlling whole system;
at least two pressure sensors adapted for sensing air back pressure which governs starting of machine and;
indicator for indicating signals received from said air pressure sensors.
2. The system for improved machining fixture as claimed in claim 1, wherein said resting pads have hole threaded at one end configured to be connected to said air pressure sensor by said air pipes.
3. The system for improved machining fixture as claimed any of the above claims, wherein other end of said hole opens on butting surface of the rest pad and job.
4. The system for improved machining fixture as claimed in claim 1, wherein said resting pads have at least two holes for mounting it on the said fixture.
5. The system for improved machining fixture as claimed in claim 1, wherein said air pressure sensors, said indicating means and said control circuit are mounted on said electrical control panel.
6. The system for improved machining fixture as claimed in claim 1, wherein said indicators are the indicating lamps.
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7. The system for improved machining fixture as claimed in claim 1, wherein said air pressure sensors are adapted to sense the back pressure of compressed air.
8. The system for improved machining fixture as claimed in claim 1, wherein starting of machine is governed by back pressure input.
9. The system for improved machining fixture substantially as herein above described and as illustrated in accompanying drawings.