US3668914A — Method of stamping metal convex articles from she…

Claim 1

Independent Claim 154 words

A method of stamping metal convex articles from sheets, preferably reservoir bottoms, on a stamping press, comprising; placing a sheet blank on a ring-shaped die, clamping the edges of said blank with a hold-down means, deforming said blank by a punch which is attached to an upper cross-head of the press so as to form a convex cylindrical portion therein, and finally shaping the article by delivering a pressurized fluid into the space between said punch and the convex part of said blank, until the final convex configuration of the article obtained, concurrently during the forming and final shaping of the article moving the edges thereof uniformly towards its center, said edge movement being responsive to a predetermined adjustment of the clamping force applied by said hold-down means to said blank, said adjustment obviating the formation of corrugations on the article and the thinning out of its cross-sectional thickness in the critical portions thereof.

Claim 2

Independent Claim 154 words

A method of stamping metal convex articles from sheets, preferably reservoir bottoms, on a stamping press, comprising; placing a sheet blank on a ring-shaped die, clamping the edges of said blank with a hold-down means, deforming said blank by a punch which is attached to an upper cross-head of the press so as to form a convex cylindrical portion therein, and finally shaping the article by delivering a pressurized fluid into the space between said punch and the convex part of said blank, until the final convex configuration of the article obtained, concurrently during the forming and final shaping of the article moving the edges thereof uniformly towards its center, said edge movement being responsive to a predetermined adjustment of the clamping force applied by said hold-down means to said blank, said adjustment obviating the formation of corrugations on the article and the thinning out of its cross-sectional thickness in the critical portions thereof.

Claim 3

Dependent Claim 29 words

A method as claimed in claim 1, comprising maintaining the fluid pressure in the spaCe between said punch and said blank within the range of 40 to 300 atm.

Claim 4

Dependent Claim 111 words

A die set for carrying out the method of stamping metal convex articles from sheet blanks, preferably reservoir bottoms, on a stamping press, comprising a punch attached to an upper movable cross-head of the press; a die mounted on the bed of the press; hold-down means for clamping the blank edges attached to said upper cross-head of the press; said punch comprising a flat disc having a radial chamfer about its blank-contacting working surface; a channel in said punch for forcing fluid between said punch and said blank; said die comprising a ring fastened to a tubular member at a distance from the plane of a lower cross-head of said press.

Claim 5

Dependent Claim 111 words

A die set for carrying out the method of stamping metal convex articles from sheet blanks, preferably reservoir bottoms, on a stamping press, comprising a punch attached to an upper movable cross-head of the press; a die mounted on the bed of the press; hold-down means for clamping the blank edges attached to said upper cross-head of the press; said punch comprising a flat disc having a radial chamfer about its blank-contacting working surface; a channel in said punch for forcing fluid between said punch and said blank; said die comprising a ring fastened to a tubular member at a distance from the plane of a lower cross-head of said press.

Claim 6

Dependent Claim 59 words

A die set as claimed in claim 3, comprising an article pusher located below said ring-shaped die in the center portion of said lower cross-head; an adjustable limiter for controlling the shape of the article, said limiter being mounted on said pusher and adapted to discontinue flow of said fluid into the space between said punch and said blank.

Claim 7

Dependent Claim 103 words

A die set as claimed in claim 3, wherein said hold-down means comprises a flat ring clampingly engaging said blank; a plurality of power cylinders connected to said upper cross-head; said power cylinders each having piston rods articulated to said flat ring; a follow-up device for adjusting the uniform movement of the edges of said blank towards its center by varying the clamping force exerted by the rods of said power cylinders on said flat ring, said device being operative during the course of the forming of said blank by said punch and during the final shaping of the article by said fluid.

Claim 8

Dependent Claim 106 words

A die set as claimed in claim 5, wherein the follow-up device comprises a system of feelers having pick-ups equidistantly spaced about the circumference of said flat ring; said feelers being provided with helical threading on their external surface; a drive for said feelers imparting motion to said feelers to follow up the positioning of the edges of said blank; pick-ups connected to said feeler drive; a valve for adjusting the required fluid pressure in respective ones of said power cylinders; and electromagnets acting upon the slide of a respective fluid-pressure adjusting valve at the instant of contact between a corresponding pick-up and the blank edge.

Claim 9

Dependent Claim 71 words

A die set as claimed in claim 6, wherein said drive to feelers comprises a system of pulleys inter-connected by a belt transmission; an electric motor having a reducing gear, said motor being adapted to impart rotation to said system of pulleys; and paired worm wheels and worms, said worms being positioned on the shafts of said pulleys, and the worm wheels being engaged on the helical thread of said feelers.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1975-06-13	1975-12-13	1976-06-13	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1979-06-13	1979-12-13	1980-06-13	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1983-06-13	1983-12-13	1984-06-13	$7700.00	Window Closed / Lapsed

Method of stamping metal convex articles from sheets

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