FORM - 2
THE PATENTS ACT, 1970
(39 OF 1970)
AND
THE PATENTS RULES, 2003
"COMPLETE SPECIFICATION"
(SEE SECTION 10; RULE 13)
"A PRESS USING SINGLE PIECE CASTING DIE FOR STAMPING OF HOOD INNER AND OUTER SHEET METAL PARTS OF CAR BODY"
MAHINDRA & MAHINDRA LIMITED
AN INDIAN COMPANY,
R&D CENTER, AUTOMOTIVE SECTOR,
89, M.I.D.C., SATPUR,
NASHIK-422 007,
MAHARASHTRA, INDIA
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES AND ASCERTAINS THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF INVENTION:-
The present invention is related to vehicle body panel manufacturing die and process of manufacturing. More particularly, the present invention is related to press using single piece casting die for stamping of hood inner and outer sheet metal parts of vehicle body.
BACKGROUND OF THE PRESENT INVENTION:-
Conventionally two separate dies are made for stamping of inner and outer. With one press stroke hood inner is formed and with second press stroke Hood Outer is formed means two separate dies are required and two press strokes are required. Another conventional way is manufacturing of two separate dies and mounting them on one common platform and then stamping together. In one press stroke, two panels are formed that means Hood Outer and Hood inner.
Therefore, to integrate two different outputs in a single stroke, simulation was done with the help of auto-form software to arrive at method plan which can take care of the different tonnage and cushion pressure requirement. Various iterations were carried out with different cushion pressure and press-tonnage to arrive at the best method plan. Even with the best method plan panel cracking and wrinkles were observed in some of the areas. As the panel design was undergoing a change we chose simultaneous engineering route minor design changes were incorporated to overcome cracking and wrinkle issue. After ensuring fool-proof method plan through simultaneous engineering and simulation and taking care of part orientation for automation of press-line, single piece casting die of the present invention was developed.
OBJECTIVES OF THE PRESENT INVENTION;-
The main objective of the present invention is to provide single piece casting die for stamping of hood inner and outer sheet metal parts of vehicle body.

Another objective of the present invention is to have a method plan for the dies in such a way that leads to die-design which can take care of different tonnage and cushion pressure requirement for inner and outer panels in a one piece casting die-set.
Still further objective of the present invention is to overcome the drawbacks of conventional stamping process known in the art.
STATEMENT OF INVENTION:-
Accordingly invention provides a press, having single piece casting die for stamping of hood inner and outer sheet metal parts of car body, comprises of a top moving press slide holding a single piece cavity die having a pair of cavities side by side for outer panel stamping and other inner panel stamping ; a bottom stationary press bolster mounted with three number of cushion pins; a single piece blank holder mounted over the said each of the cushion pins; a pair of three piece punch mounted over the said bottom stationary press bolster side by side facing the said cavity die; one of the said three piece punch meant for hood inner sheet stamping and other for hood outer sheet stamping; and a method plan adapted by using auto form software for the die in such a way that leads to die-design which takes care of different tonnage and cushion pressure requirement for inner and outer panels in a one piece casting die-set.
DESCRIPTION OF THE FIGURES:-
Figure 1 shows single piece casting die for stamping of hood inner and outer sheet metal parts of vehicle body in accordance with the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION:-
Hood Outer and Hood inner has major difference in terms of skin, profile, features, Formability and quality and tonnage requirements. Therefore a dedicated effort has been made to have the die face generation of both inner

and Outer draw dies in such a way that tonnage requirement of both the parts get balanced without affecting the skin panel quality of Hood Outer.
Referring to figurel, single piece casting die of the present invention comprises of press slide (1), single piece cavity (2), single piece blank holder (3), three piece punch (4), cushion pin (5), press bolster (6), hood outer sheet (7) and hood inner sheet (8). As shown in figure 1, items (2), (3) and (4) are stamping die elements. Items (1), (4) and (6) are press elements. Dies elements are made with single piece casting. Item (3) is inserted in item (4). Item (2) is inserted in the item (3) and this is how the Die assembly is carried out.
Total die assembly is clamped on mechanical press. Item (2) is mounted on item (1). Assembly of item (3) and (4) is clamped on item (6). Item (3) is in floating condition which is rested on item (5) and guided on item (4).
In the present invention, Hood Outer and Hood Inner sheet metal parts (required for car body) are stamped together. Single piece casting die is made for stamping of hood inner and outer together. One blank (plane sheet metal) is loaded for outer and another blank is loaded for inner in single piece casting die. After stamping, plane sheet metal is formed to required shape of inner and outer part means in one press stroke two parts are formed, one is Hood Outer and another is Hood Inner.
Thus the present invention targets to have a method plan for the dies in such a way that leads to die-design which can take care of different tonnage and cushion pressure requirement for inner and outer panels in a one piece casting die-set. The die set as disclosed above is manufactured and productionized for in-house use. It is in running condition and used for car body panel stamping.
The technical advantages achieved by this process invention are as under-• One set of die on press is eliminated.

• Die Manufacturing and initial prove-out time is reduced.
• Die Material cost is reduced.
• Press capacity is reduced for some other job stamping.
• Maximum press tonnage capacity utilisation is achieved.
• Outer and inner press parameters commonization with delivering same quality level of sheet metal body panel is achieved.
• Improvement in Efficiency e.g. Reduction in cycle time, reduction of waste, etc.
• Capacity improvement-5% improvement in press-line .
• Set-up time reduction-50% w.r.t. current set up time for hood inner and outer.
• Efficiency improvement- 2% due reduction in no of stroke per vehicle.
• No need of panel offloading to cater the increased volume requirement
and also possible to cater the spares requirement.
The other benefits in light of economic significance of the present invention are,
- Capital investment saving of 18% w.r.t. separate die set (Rs. 60 lacs).
- Reduction of one line stroke gives the benefit of 117 Rs/Veh saving, annualised saving of Rs 89.7 lacs.( This is ongoing saving every year).
- After implementation till date the saving received is 112.6 lacs. (Including capital investment)
- As a part of customer delight, due to combined die set up time and die handling has been reduced.

WE CLAIM:-
1. A press, having single piece casting die for stamping of hood inner and outer sheet metal parts of car body, comprises of a top moving press slide holding a single piece cavity die having a pair of cavities side by side for outer panel stamping and other inner panel stamping ; a bottom stationary press bolster mounted with three number of cushion pins; a single piece blank holder mounted over the said each of the cushion pins; a pair of three piece punch mounted over the said bottom stationary press bolster side by side facing the said cavity die; one of the said three piece punch meant for hood inner sheet stamping and other for hood outer sheet stamping; and a method plan adapted by using auto form software for the die in such a way that leads to die-design which takes care of different tonnage and cushion pressure requirement for inner and outer panels in a one piece casting die-set.