An Improved Method of and Apparatus for Manufacturing Hollow Ware.
Year: 1899

page_text: Date of Application, 18th Mar., 1899
Complete Specification Left, 1st July, 1899-Accepted, 11th Nov., 1899
PROVISIONAL SPECIFICATION.
An Improved Method of and Apparatus for Manufacturing Hollow
Ware.
I, LUIGI STAMPACCHIA, of 2, Via Farini, Bologna, Italy, Engineer, do hereby
declare the nature of this invention to be as follows:-
My invention relates to the manufacture of deep hollow ware, principally
to such manufacture from thin metallic plates or sheets.
My principal object is to produce very deep drawn articles, that is, articles
deep in proportion to their diameter, from thin sheet, by a minimum number of
operations in the cold, dispensing entirely with hot metal drawing or with heat-
ing and annealing operations.
The invention however may be applied with advantage to thicker plates or
sheets operated at a suitable heat.
My invention consists in a special process of drawing, and in new apparatus
for carrying this special process into effect. The new process consists 1st. In
cupping metal plate or sheet in the usual manner, and then drawing the cup so
produced through a die, first between inclined surfaces of the dic and an
annular punch also having inclined surfaces, over a certain rounded projecting
surface within the die by means of an inner solid punch, this part of the opera-
tion increasing the drawn depth of the article, without diminishing the thick-
ness of the material, or even permitting of increase of thickness due to reduc-
tion in diameter. 2nd. In drawing down the sides of the article produced by a
second operating edge within the die of smaller diameter than the first bending
or forming edge, this second edge operating together with the internal solid
punch to reduce the thickness of the sides of the article, and thus increase the
depth of the draw.
An article so drawn by one operation after cupping attains a relatively great
depth. By drawing through a second die, with annular and solid punches
similarly arranged, I am enabled, without heating or annealing, to produce a
hollow article of a depth equal to or greater than its diameter. By my inven-
tion therefore I produce exceedingly deep drawn articles from thin plates in two
draws after the initial cupping, and without any annealing.
My new apparatus consists in a drawing die, comprising an inclined circular
surface, and a bending surface, together with an annular punch having a
similarly inclined surface, and an internal solid punch having rounded advance
edges and a central cavity, with an air discharge passage through the punch,
the die being formed with a second ring surface for drawing the metal and
increasing the depth.
As a subsidiary part of my invention, I also apply a spring operated extractor,
which snaps over the end of the plate when the punch draws it past the
extractor, and on the return of the punch removes the drawn article from the
punch.
In one construction of dies and punches or plungers, carrying my invention

page_text: into effect, I construct the die in four ring sections, one ring fitting the top of
the next succeeding ring, and checked into it or otherwise fastened to it to keep
the relative positions accurately. The upper ring I form or fairly hard steel,
and I provide in it an inclined surface passing from a larger diameter-the
outside diameter of the eup to be inserted-to a smaller diameter, the smaller
diameter being the external diameter of the article to be formed at that particular
draw.
I cause the inclined or conical surface to terminate at the upper end in a
concave curved ring surface, leading gently from the diameter of the outside
of the cup to the conical surface. At the lower end of the conical surface I
provide a rounded ring projecting surface, struck with a suitable radius, and
passing smoothly from the conical surface. I reduce the metal under this bead
or ring, to leave a clear space from the middle of the curve, in order to prevent
friction between the die and the plunger where such friction would be disad-
vantageous. Under the first mentioned steel ring carrying the conical surface
with its entrance and exit curves, I provide another steel plate, which plate I
construct with a drawing surface projecting nearer to the plunger, than the
forming surface first described. The distance between this drawing surface
and the plunger is determined by the thickness of metal desired, and the amount
of reduction permissible by the draw. The surface is suitably shaped to operate
gradually upon the metal, in order to draw as much as may be desired without
straining the metal. Another ring is provided also of steel, on which this
drawing ring is mounted, and the lower ring checks upon a metal block, which
may or may not be of steel, the surface underneath the drawing edge being
removed to prevent contact with the outside of the vessel being formed. The
lower block carries an extractor, which consists of a series of arc shaped pro-
jecting trippers or pawls held up by suitable springs. The punch, in carrying
the article formed past the tripper or pawl, depresses the end, and immediately
the edge of the formed article passes the tripper, the spring forces it up, and on
the return stroke the article is removed from the punch, and allowed to fall out
of the machine.
To operate with the forming and drawing die, which I have described, I
provide two punches, one a solid punch, sliding within an outer punch of
annular shape. The annular punch is arranged with a conical face of the same
configuration as the conical surface in the die, and its lower edge is rounded
to prevent it from cutting the metal when it is forced down. The internal
punch also is round at its outer edges, to approximate nearly in shape to the
next conical surfaco die to be used in the process, that is, it is so rounded that
the deep article produced by one draw fits approximately into the die used for the
next and last formation and draw. The angle of the conical converging surface
may be varied within certain limits, but 45 degrees I find to be a limiting
angle, that is, 45 degrees from the vertical internal plunger. Some metals
require greater pressures to avoid wrinkling in the process of converging from
the larger diameter to the smaller diameter. For such metals a more acute
angle such an angle, for instance, as 30 degrees-is suitable. The radius, too.
of the curve passing from the cone to the cylindrical surface depends upon the
nature of the metal and its thickness. Thus, with a thick metal, the radius
must by greater than with a thin metal.
The angle, too, of the conical surfaces, varies with the thickness of the metal
operated on. When greater pressure is required, the angle is more acute.
The object of the variations in augle and radius of the forming curve is to
obtain a sufficient and uniform pressure upon the metal in the act of converging
from a large diameter to a small diameter to prevent the formation of cording
or wrinkling. The possible pressure of course is limited by the tensile strength
of the material, and my object is to obtain the necessary normal surface pres
sures to prevent wrinkling during converging, while at the same time reducing
friction to a minimum, so as to avoid tearing out the bottom of the vessel being

page_text: formed.
find, too, that the radius of the forming surface requires to be varied
with the nature of the material used. For a given article, for instance, formed
in steel or soft iron, the suitable radius to be 1; in copper, brass, or nickel, the
radius would require to be about 1.25, while in zinc or aluminium it would
require to be 1.5.
An Improved Method of and Apparatus for Manufacturing Hollow
Ware,
I, LUIGI STAMPACCHLA, of 2, Via Farini, Bologna, Italy, Engineer, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
My invention relates to the manufacture of deep hollow ware, principally
to such manufacture from thin metallic plates or sheets..
My principal object is to produce very deep drawn articles, that is, articles
deep in proportion to their diameter from thin sheet, by a minimum number of
operations in the cold, dispensing entirely with hot metal drawing or with heat-
ing and annealing operations.
The invention, however, may be applied with advantage to thicker plates or
sheets operated at a suitable heat.
My invention consists in a special process of drawing, and in new apparatus
for carrying this special process into effect. The new process consists Ist:-In
cupping metal plate or sheet in the usual manner, and then drawing the cup so
produced through a die, first between inclined surfaces of the die and an
annular punch also having inclined surfaces, then over a certain rounded pro-
jecting surface within the die by means of an inner solid punch, this part of the
operation increasing the drawn depth of the article without diminishing the
thickness of the material, and may even permit of increase of thickness due to
reduction in diameter. 2nd:-In drawing down the sides of the article by
means of a second operating edge, within the die, of sunaller diameter than the
first bending or forming edge, this second edge operating together with the
internal solid punch to reduce the thickness of the sides of the article, and thus
increase the depth of the draw, and to give an improved surface finish to the
drawn articles.
An article so drawn by one operation after cupping attains a relatively great
depth. By drawing through a second set of dies with annular and solid punches
similarly arranged, I am enabled, without heating or annealing, to produce a
hollow article of a depth equal to or greater than its diameter. By my invention
therefore I produce exceedingly deep drawn articles from thin plates in two
draws after the initial cuppings, and without any annealing.
My new apparatus consists in a drawing die, comprising an inclined circular
surface, and a bending surface, together with an annular punch having a
similarly inclined surface, and an internal solid punch having rounded advance
edges and a central cavity, with an air discharge passage through the punch,
the dio being formed with a second ring surface for drawing the metal and
increasing the depth.
As a subsidiary part of my invention I also employ a spring operated extractor,
which snap over the end of the plate when the punch draws it past the

page_text: extractor, and on the return of the punch removes the drawn article from the
punch.
In one construction of dies and punches or plungers carrying my invention
into effect, I construct the die in four ring sections, one ring fitting the top of
the next succeeding ring, and checked into it or otherwise fastened to it to keep
the relative positions accurately. The upper ring I form of fairly hard steel,
and I provide in it an inclined surface passing from a larger diameter-the
outside diameter of the cup to be inserted-to a smaller diameter, the smaller
diameter being approximately the external diameter of the article to be formed
at that particular draw.
I cause the inclined or conical surface to terminate at the upper end in a
concave curved ring surface, leading gently from the diameter of the outside
of the cup to the conical surface. At the lower end of the conical surface I
provide a rounded ring projecting surface, struck with a suitable radius, and
passing smoothly from the conical surface. I reduce the metal under this bead
or ring, to leave a clear space from the middle of the curve, in order to prevent
friction between the die and the plunger where such friction would be disad-
vantageous. Under the first mentioned steel ring carrying the conical surface
with its entrance and exit curves, I provide another steel ring, which ring I
construct with a drawing surface projecting nearer to the plunger, than the
forming surface first described. The distance between this drawing surface
and the plunger is determined by the thickness of metal desired, and the amount
of reduction permissible by the draw. The surface is suitably shaped to operate
gradually upon the metal, in order to draw as much as may be desired without
straining the metal. Another ring is provided also of steel, on which this
drawing ring is mounted, and the lower ring checks upon a metal block, which
may or may not be of steel, the surface underneath the drawing edge being
removed to prevent contact with the outside of the vessel being formed. The
lower block carries an extractor, which consists of a series of are shaped pro-
jecting trippers or pawls held up by suitable springs. The punch, in carrying
the article formed past the tripper or pawl, depresses the end, and immediately
the edge of the formed article passes the tripper, the spring forces it up, and on
the return stroke the article is removed from the punch, and allowed to fall out
of the machine.
To operate with the forming and drawing die, which I have described, I
provide two punches, one a solid punch sliding within an outer punch of
annular shape. The annular punch is arranged with a conical face of the same
configuration as the conical surface in the die, and its lower edge is rounded
to prevent it from cutting the metal when it is forced down. The internal
punch also is rounded at its outer edges to approximate nearly in shape to the
next conical surface die to be used in the process, that is, it is so rounded that
the deep article produced by one draw fits approximately into the die used for the
next and last formation and draw. The angle of the conical converging surface
may be varied within certain limits, but 45 degrees I find to be a limiting
angle that is, 45 degrees from the vertical internal plunger. Some metals
require greater pressures to avoid wrinkling in the process of converging from
the larger diameter to the smaller diameter. For such metals a more acute
angle, such an angle, for instance, as 30 degrees, is suitable, the radius, too, of
the curve passing from the cone to the cylindrical surface depends upon the
nature of the metal and its thickness. Thus, with a thick metal, the radius
must be greater than with a thin metal.
The angle too of the conical surfaces, varies with the thickness of the metal
operated on. When greater pressure is required, the angle is more acute.
The object of the variations in angle and radius of the forming curve is to
obtain a sufficient and uniform pressure upon the metal in the act of converging
from a large diameter to a small diameter to prevent the formation of a cording

page_text: or wrinkling. The possible pressure of course is limited by the tensile strength
of the material, and my object is to obtain the necessary normal surface pres-
sures to prevent wrinkling during converging, while at the same time reducing
friction to a minimum, so as to avoid tearing out the bottom of the vessel being
formed.
I find, too, that the radius of the forming surface requires to be varied with
the nature of the material used. For a given article, for instance, formed in steel
or soft iron, assuming the suitable radius to be 1; then in copper, brass, or
nickel, the radius would require to be about 1.25, while in zinc or aluminium it
would require to be 1.5.
In carrying my invention into effect according to one modification, as illus-
trated in the accompanying drawing, which is a vertical section through my
improved apparatus, showing an article in the process of being made, a hollow
die is built up of a number of steel rings checked into each other or otherwise
fastened to avoid displacement; these rings are lettered A, B, C, and D. The
uppermost ring A is made of fairly hard steel, and has an internal inclined
surface whose greatest diameter is equal to the outside diameter of the cup to
be inserted, and whose least diameter is just a little larger than the outside
diameter of the cup produced by this draw. A section of the inclined surface
commences at the top with a concave curve a. It has then a straight or nearly
straight part a', and then a convex curve a³. The curve a³ is continued beyond
the vertical so as to increase again the internal diameter of the die. This is to
prevent friction when the cup is being drawn through the die.
The angle which makes with the axis of the die may be varied within cer-
tain limits. The best angle to use depends on the thickness and nature of the
material, but 45 degrees I find to be a limiting angle, that is, 45 degrees to the
axis of the die. In many cases 45 degrees is too great an angle to prevent
wrinkling or creasing, and in such cases I use an angle of say 30 degrees to the
axis, and thereby obtain greater normal pressure on the surface of the plate
dealt with. The radii of the curves a and also depend on the nature and
thickness of material used, and also on the diameter of the cup. The relative
proportions indicated in the drawing of the radii of the curves a and a to the
diameter of the cup are suitable for tin plate of ordinary thickness.
Under the ring A is the second steel ring B, which ring I construct with a
drawing surface having a slightly less diameter than the ring A at its narrowest
part a The difference between the inside diameter of the ring B and the out-
side diameter of the punch hereinafter described depends on the thickness of
metal desired, and the amount of reduction permissible in this part of the draw.
The surface is suitably shaped with a gradual taper 7 so as to operate gradually
upon the metal in order to draw as much as may be desired without straining
the metal, and so as to produce a good finish on the article produced, and is cut
away beneath the drawing edge as at 31 to reduce friction. The ring C is below B,
and is of such a diameter as not to come in contact with the cup being drawn.
This ring is checked on the metal block D, and is also quite clear of the cup
being drawn. The block D carries an extractor, which consists of a series of arc
shaped projecting trippers or pawls G pivoted on carriers E and held up by
suitable springs such as F. The carriers E are secured to blocks H which are
held in place in the block D by pins h or by other suitable means. The punch P
in carrying the article formed past the trippers or pawls G, depresses the end
of each pawl, and, immediately the edge of the formed article passes the trippers,
they are forced up by the springs, so that, on the return stroke, the article is
removed from the punch and allowed to fall out of the machine.
To operate with the forming and drawing die which I have described I provide
two punches, one a solid punch P, sliding within another punch of annular shape
Q. The annular punch Q has a conical face 9 of the same configuration as the
surface of the die block A, except for its lower edge which is rounded to prevent
it from cutting the metal when the punch is forced down. The internal punch P

page_text: is also rounded at its outer edges to approximate nearly in shape to the next
conical surface die to be used for the next formation and draw. The inner punch
has also a suitable internal channel or channels for the escape of air.
The process of drawing is carried out in the following way:-The metal
plate, having been dished, is placed under the punch in the part a of the die. The
two punches then descend together, and the annular punch Q presses the metal
into the upper conical die A. The inner solid punch P now continues its course
and draws the metal over the rounded surface a³; by this means all creasing
or wrinkling of the metal is prevented. The metal is now drawn through the
second ring B and the thickness of metal is reduced, giving a good finish on the
drawn article, the internal diameter of the.cup remaining unaltered. The punch
depresses the metal below the extracting pawls of the carrier E, which, as soon
as the top of the cup has passed them, snap up and prevent the return of the cup
on the back stroke of the punch, thus causing the finished cup to drop out of
the machine.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:-
1. The herein described method of drawing metal cups having considerable
depth in relation to their diameter, as and for the purposes specified.
2. In apparatus for producing deep drawn metal articles a die such as A
having a concave entering surface, a conical or nearly conical contracting surface
and a convex exit surface, as and for the purposes net forth.
3. In the manufacture of deep drawn cups, the combination of a forming
draw such as that between die A and punch Q, with a finishing draw such as
that between punch P and the die B, substantially as described.
4. In apparatus for producing deep drawn metal articles the combination of
punches such as P and Q with special dies such as A and B, substantially as
herein before described.
6. In apparatus for producing deep drawn metal articles, the combination with
the punches and dies, as claimed in Claim 3 of an automatic cup extractor,
substantially as described.
6. The hereinbefore described apparatus for producing deep drawn articles,
all constructed and operated substantially as herein before described with refer-
ence to the accompanying drawing.
T.... 1800
day of July
T..1.. 1900
MARKS & CLERK,
18, Southampton Buildings, London, W.C.,
13, Temple Street, Birmingham, and 25, Cross Street, Manchester, Agents