FORM 2


THE PATENTS ACT, 1970 (39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A -method of making segmental compound blanking tool elements
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
Inventor
Keluskar Chandrashekar, Crompton Greaves Limited, Tool Room, M-6 Stamping Division, Kanjurmarg (East), Mumbai 400 042, Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:


FIELD OF THE INVENTION
This invention relates to a method of making segmental compound blanking tool elements.
BACKGROUND OF THE INVENTION
Stator cores of rotating electric machines like motors or alternators are made from segmental laminations generally in a punching press such as H-frame press comprising segmental compound blanking tool elements which include die, punch, stripper and ejector and die and punch backups. The blanking tool elements are made by drilling clamping holes in the die blanks in the inner portions thereof corresponding dies and in the punch blanks in the outer portions thereof corresponding to punches followed by hardening the blanks by heating them usually at 800 to 1000°C. On cooling the blanks to ambient temperature, punches are wire cut from the outer portions of punch blanks and the inner portions of the punch blanks are disposed of as slug and scrap. Dies are wire cut from the inner portions of die blanks and the outer portions of the die blanks are disposed of as slug and scrap. Clamping holes are drilled in the stripper blanks and ejector blanks in the inner portions and outer portions thereof corresponding to ejector and stripper respectively and the blanks are hardened by heating them usually at 800 to 1000°C. On cooling the blanks to ambient temperature, strippers are wire cut from the inner portions of stripper blanks and the outer portions of the stripper blanks are disposed of as slug and scrap. Ejectors are wire cut from the outer portions of the ejector blanks and the inner portions of the ejector blanks are disposed of as slug and scrap. Die backups and punch backups or spacers are required for making up the required height of dies
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and punches, respectively. These backups are wire cut from die and punch backup blanks respectively and annealed usually at 600 to 800°C and cooled to ambient temperature before the clamping holes are drilled therein. The above method in general requires separate blanks for dies, punches, strippers and ejectors and die backups and punch backups and hence a large quantity of material. It generates a large quantity of wastage material. It also requires substantial wire cutting. Therefore, material cost and wire cutting cost are very high and there is substantial wastage of material. Production time is increased and productivity is reduced. Further, it is also cumbersome and difficult to carry out as it requires to handle large number of blanks and substantial wire cutting.
OBJECTS OF THE INVENTION
An object of the invention is to provide a method of making segmental compound blanking tool elements, which method requires reduced number of blanks and reduced wire cutting to make the tool elements and which method prevents wastage of material and is economical.
Another object of the invention is to provide a method of making segmental compound blanking tool elements, which method reduces production cost and time and increases productivity.
Another object of the invention is to provide a method of making segmental compound blanking tool elements which method is simple and easy and convenient to carry out.
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DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a method of making segmental
compound blanking tool elements, the method comprising the following steps:
i) drilling clamping holes in a first blank of segmental lamination corresponding
to a punch in the inner portion thereof and drilling clamping holes in a second blank
of segmental lamination corresponding to a die in the outer portion thereof;
ii) hardening the first and second blanks by heating them at 800 to 1000°C
followed by cooling them to ambient temperature;
iii) wire cutting a punch from the inner portion of the said first blank and wire
cutting a die from the outer portion of said second blank;
iv) annealing the outer portion of the said first blank and the inner portion of (he
said second blank by heating at 600 to 800°C followed by cooling the outer and inner
portions to ambient temperature;
v) drilling clamping holes in the outer portion of the said first blank
corresponding to the clamping holes in the die to form a die backup and drilling
clamping holes in the inner portion of said second blank corresponding to the
clamping holes in the punch to form a punch backup;
vi) drilling clamping holes in a third blank of segmental lamination
corresponding to an ejector in the inner portion thereof and a stripper in the outer
portion thereof;
vii) hardening the third blank by heating at 800 to 1000°C followed by cooling to
ambient temperature; and
(viii) wire cutting the third blank with the inner portion thereof forming an ejector
and the outer portion thereof forming a stripper.
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The following is a detailed description of the invention with reference to the accompanying drawings, in which
Fig 1 is a blank of segmental lamination and Figs la and lb are a punch and a die backup wire cut from the blank of Fig 1 respectively;
Fig 2 is a blank of segmental lamination and Figs 2a and 2b are a die and a punch backup wire cut from the blank of Fig 2 respectively;
Fig 3 is a blank of segmental lamination and Figs 3a and 3b are an ejector and stripper wire cut from the blank of Fig 3 respectively.
According to the invention, clamping holes are drilled in the blank 2 of Fig 1 of the accompanying drawings in the inner portion thereof corresponding to a punch and clamping holes are drilled in the blank 4 of Fig 2 of the accompanying drawings in the outer portion thereof corresponding to a die. The blanks 2 and 4 are hardened by heating them at 800 to 1000°C followed by cooling them to ambient temperature. Punch 5 is wire cut from the inner portion of the blank 2 and a die 6 is wire cut from the outer portion of blank 4 (Figs la and 2a of the accompanying drawings respectively). The outer portion of blank 2 and the inner portion of blank 4 are annealed by heating them to 600 to 800°C followed by cooling the outer and inner portions to ambient temperature. Clamping holes are drilled in the outer portion corresponding to clamping holes in the die to form a die backup 8 (Fig lb of the accompanying drawings). Clamping holes are drilled in the inner portion corresponding to the clamping holes in the punch to form a punch backup 10 (Fig 2b
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of the accompanying drawings). Clamping holes are drilled in the blank 11 of Fig 3 of the accompanying drawings in the inner and outer portions thereof corresponding to an ejector and a stripper, respectively. Blank 11 is hardened by heating at 800 to 1000°C followed by cooling to ambient temperature. Blank 11 is wire cut such that the inner portion thereof forms an ejector 12 as shown in Fig 3a of the accompanying drawings and the outer portion thereof forms a stripper 13 as shown in Fig 3b of the accompanying drawings.
According to the invention the segmental blanking tool elements namely die and die back up, punch and punch backup, ejector and stripper are made from three blanks of segmental laminations. The number of blanks is thus substantially reduced. There is considerable saving in material and wastage of material is completely eliminated. Material cost is considerably reduced. Wire cutting is substantially reduced correspondingly reducing wire cutting cost. Production time is considerably reduced and productivity is substantially increased. The method is also simple and easy and convenient to carry out.
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We claim
1. A method of making segmental compound blanking tool elements, the method
comprising the following steps:
i) drilling clamping holes in a first blank of segmental lamination corresponding
to a punch in the inner portion thereof and drilling clamping holes in a second blank
of segmental lamination corresponding to a die in the outer portion thereof;
ii) hardening the first and second blanks by heating them at 800 to 1000°C
followed by cooling them to ambient temperature;
iii) wire cutting a punch from the inner portion of the said first blank and wire
cutting a die from the outer portion of said second blank;
iv) annealing the outer portion of the said first blank and the inner portion of the
said second blank by heating at 600 to 800°C followed by cooling the outer and inner
portions to ambient temperature;
v) drilling clamping holes in the outer portion of the said first blank
corresponding to the clamping holes in the die to form a die backup and drilling
clamping holes in the inner portion of said second blank corresponding to the
clamping holes in the punch to form a punch backup;
vi) drilling clamping holes in a third blank of segmental lamination
corresponding to an ejector in the inner portion thereof and a stripper in the outer
portion thereof;
vii) hardening the third blank by heating at 800 to 1000°C followed by cooling to
ambient temperature; and
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(viii) wire cutting the third blank with the inner portion thereof forming an ejector and the outer portion thereof forming a stripper.
Dated this 29th day of January 2009
(Jose M A)
of Khaitan&Co
Agent for the Applicants