An Improved Hydraulic Drawing Press.
Year: 1894

page_text: Date of Application, 13th Nov., 1894-Accepted, 5th Jan., 1895
An Improved Hydraulic Drawing Press.
I, LOUIS SCHULER, of Goeppingen, in the Kingdom of Wurtemberg, Germany,
Manufacturer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement :-
My invention relates to an improved hydraulic drawing press characterized
essentially by two pistons, constructed the one inside the other, one of which acts
on the plate-holder, and the other upon the drawing die.
In order to secure uninterrupted working the drawing press is provided with an
automatic reversing mechanism, which reverses the inner piston on the upstroke,
and the outer one on the downstroke.
Arrangements are also made which allow of the downstroke being effected more
quickly than the upstroke.
To enable my invention to be fully understood I will describe how it can be
carried into practice by reference to the accompanying drawing, in which :-
:-
Figure 1 is a vertical section of a hydraulic drawing press constructed according
to my invention; and,
Figure 2 is a similar view illustrating a modification.
A piston 6 is arranged to slide in the frame a of the press, and in this piston is a
second and smaller piston c. The outer piston moves the table or plate holder d,
whilst the inner piston c moves the drawing die.
On the under side of the outer piston of the arrangement shewn in Figure 1 is
provided a valve e which is pressed up to the piston by the action of a spring e¹ as
soon as the piston arrives at the lowest point of its stroke.
The valve e is guided by a rod the upper end of which is rigidly connected
with the piston c, whilst the lower end is guided by a tubular support secured to
the frame. The interior diameter of the support is greater than that of the rod r³,
so that water under pressure may be able to enter it."
The water under pressure is led in through a valve in the direction of the arrow
and led off by a valve g. These valves, 9 are so connected with each other that
when one is open the other is shut, and conversely. If for example the valve ƒ be
pressed home on its seating, the valve g is raised from its seating by the compression
of the spring s.
If, on the other hand, the valve be raised from its seating, the spring s drives
the valve g back, and the latter is closed.
The movement of the outer piston band of the table d is limited above by
clamping nuts k, k and below by a stop whilst the inner piston c and the drawing
die strike on the throw-out plate m in the upstroke. The latter is connected to the
cross-bar n which comes into contact with the stop o on the guide rod p, as the
upstroke proceeds. On the lower end of the rod p there is secured a bell-crank
lever q rotating on q¹ which is connected with the valve f.
The two pistons begin their upward movement at the same time, but the outer
one 6 is arrested as soon as the plate-holder which is connected with it strikes
against the matrix, or the table d comes into contact with the clamping nuts k, k.
Since the valve e is by this time somewhat separated from the piston
pressure can enter below the inner piston, so that the latter, and with it the drawing
die, continues its upward movement, until the stop o is raised by the cross bar.
water under

page_text: At
The action of the drawing press is thereby reversed, since the rod P
raised, and the valve f is closed by the action of the bell-crank lever q.
the same moment, however, the valve is opened, so that the water under
pressure is able to issue from the piston and the latter aud the drawing-tools are
moved back.
Just before the lowest position the prolongation d' of the table d strikes against
the lower stop and this reverses the motion, since the rod p is pressed down, the
pressure valve opened, and the exit valve g closed.
The water under pressure is now admitted again, and the upward motion is thus
caused to repeat itself.
In order to move the drawing die down again, mechanically, as soon as it
encounters any opposition to its downward motion, whether from the adhesion of
the drawn vessel to the die, or from any other increase of friction, I provide
the rod already referred to which carries a small piston as shewn. The
downward motion of the inner piston e would, in the case supposed, proceed as
follows:-
:-
As soon as the outer piston band with it the table d has reached its lowest point,
the reversal is effected as above described, and the water under pressure flows in.
The latter presses first upon the piston of the rod r, whereupon the latter, and with
it the piston e are moved downwards, before the upward movement (caused by the
continued entrance of the water under pressure) results.
For the reason that the exit opening for the water is greater than the inlet, the
This effect is
descent of the piston is effected in a shorter time than the ascent.
augmented still further by the fact that the outflowing waste water is sucked
through the air-tight water space which is first deprived of the water under
pressure by a pump, whereby a vacuum chamber is formed.
Usually, that is to say, when no opposition is offered to the die both pistons b, c
reach their lowest point at the same moment, since the die, i.e., the inner piston c is
loaded with the cross-bar n which forms a weight causing the inner piston to descend
more quickly than the outer piston. Any other form of weight can obviously be.
used for this purpose.
The form of construction shewn in Figure 2 is similar to the one just described,
only in this case instead of the valve e there is a valve 2 placed in the end of the
piston b, which valve is provided with a small opening e³ and is pressed up to the
piston b by a spring e as shewn in the drawing. The rod and the support ŕ are
here dispensed with.
The mode of action of this modification is similar to that of the form previously
described. When the water under pressure enters the large piston rises, and the
small one with it, so far that the table d strikes against the nuts k, k but in the
Whilst
meantime some water under pressure has entered through the opening e³.
the piston bis at rest the space between the valve e² and the lower part of the
piston c continues to fill until the pressure on both sides of the valve e² reaches the
same point.
When this has happened, the valve falls down, the water under pressure can
enter freely, and the small piston continues to rise, until the die strikes the plate m
and is thereby reversed. The further mode of action is then the same as that
described for the previous form of construction.
It is evident that the form of the valves, e or e², as also of the valves f, g may
undergo slight modifications, without altering anything of the substance of the
invention.
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. A hydraulic drawing press comprising two pistons b, c arranged one within the
other, one of which pistons b moves the plate-holder, and the other piston c moves

page_text: 2. In a hydraulic drawing press, the combination of the pistons b, c adapted to
operate the plate holder and die respectively with a system of valves f, g, in such a
way that the inner piston c as it ascends, and the outer piston b as it descends,
alternately open and shut the valves f, g which are connected to each other, where-
upon the press reverses, and continuous working is effected, substantially as set
forth.
3. In a hydraulic drawing press having two pistons arranged one within the
other and adapted to operate the plate holder and die respectively. the com-
bination with the inner piston c of a rod r carrying a piston guided in a support r
which rod draws the piston c downward, as soon as the die which is connected with
the latter encounters any resistance, substantially as set forth.
4. In a hydraulic drawing press having two pistons arranged one within the
other and adapted to operate the plate holder and die respectively, an exit opening
for the water made of larger size than the inlet, so that the descent of the piston
shall be effected more quickly than the upward movement, substantially as set
forth.
5. In a hydraulic drawing press having two pistons arranged one within the
other and adapted to operate the plate holder and die respectively, an air-tight
chamber for the water in which a vacuum is formed by the removal of the water
under pressure, whereby the descent of the piston is hastened, substantially as set
forth.
6. In a hydraulic drawing press having two pistons arranged one within the
other and adapted to operate the plate holder and die respectively, the combination
with the inner piston
cor the die of a suitable weight, such as n, in order to
cause the said inner piston to descend more quickly than the outer piston b so
that both pistons may reach their lowest point at the same moment, substantially
as set forth.
7. In a hydraulic drawing press having two pistons arranged one within the
a valve e which
other and adapted to operate the plate holder and die respectively,
is pressed up to the outer piston by means of a spring e as soon as the piston has
reached its lowest point, substantially as set forth.
8. The modified arrangement of hydraulic drawing press having two pistons
arranged one within the other and adapted to operate the plate holder and die
respectively, in which a valve e2 is attached to the piston which valve is kept up
to the piston by a spring & and is provided with an opening e³ for the water under
pressure, the rod and its piston and support shewn in Figure 1 being dispensed
with, substantially as set forth.
1
1001
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.