IMPROVEMENTS IN STEAM HÁMMERS
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by William Robert Lake at
"
the Office of the Commissioners of Patents, with his Petition, on the.
15th May 1874.-A communication from abroad by T. Pregél, of:
Wiener, Neustadt, Empire of Austria, Engineer.
I, WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co.,
Patent Agents, Southampton Buildings, London, do hereby declare the:
nature of the said Invention for “IMPROVEMENTS IN STEAM HÁMMERS,” a:
communication, to be as follows:-
These improvements relate to that class of steam hammers in which
the hammer head is connected by the piston rod to a piston working in
a vertical steam cylinder. They consist in a peculiar arrangement of.
steam distributing ports and valves for the purpose of utilizing above
the piston steam conducted from beneath the piston, and further
in arrangements for facilitating the movement of unbalanced slide
valves.
The utilization of steam from below the piston for acting above the
piston is attained in the following manner :-After the steam which has
entered below the piston has raised it to a certain height, communication

page_text: is made from beneath the piston to the space above it by opening a valve
leading to an inlet arranged at some distance below the top of the
cylinder. This having taken place and there. being thereupon no outlet
open for the escape of the steam from either side of the piston, there
will temporarily be the same pressure on both sides, but as by that time
the piston has already attained a certain energy it continues to proceed
upwards, and passing the before-mentioned inlet to the upper space in
the cylinder compresses the steam now confined above.
The pressure on the upper side of the piston will thereupon be not
only equal to that existing at the time of the entrance of the steam
from below the piston, but will also be increased by the compression
proceeding from the pistons rising until the whole of the vis viva or
energy of the hammer is absorbed in this steam confined above the
piston. On the lower part of the cylinder being then caused to com-
municate with the atmosphere by opening an exhaust valve, the steam
beneath the piston escapes, and the pressure below the piston will be but
slightly different from the atmospheric pressure. The piston thereupon
falls with a speed increased by the pressure of the steam taken from
below the piston and compressed above it in the upper space of the
cylinder. The initial pressure of this steam compressed above the
piston is all the higher the more head space the forging takes up, the
expansion being then proportionally lower, so that this construction of
steam hammer allows a complete utilization of a volume of steam
corresponding to the height of the forging.
c
In order to insure the admission of steam from below the piston to
the space above it, even if the valve used for this purpose should fail to
act, a second opening may be arranged in the side of the cylinder a
little below the inlet mentioned above, and in such wise as to com- :
municate with this inlet through a pipe outside the cylinder. The
distance between these two openings is made greater than the thickness
of the piston, so that as soon as the piston has passed this lower opening
the steam beneath the piston must communicate through the lower
opening with the inlet above the piston until the piston proceeding
upwards first closes and then passes this upper opening.
For distributing the steam in this arrangement either common slide
valves, piston slide valves, or other suitable valves can be applied.
When unbalanced slide valves are used and when they are to be
moved by hand and with a single lever an exact distribution of steam
.
:

page_text: with a tightly closing valve may be attained in the following manner :—
The inlet and outlet openings for the steam below the piston are each
fitted with a slide valve, preferably with a short stroke, and these valves
are moved in such wise that when one of the valves is moving the other
is at rest, and vice versa. For effecting this motion discs or plates with
curved slots or grooves are used in which the lower ends of the valve
rods slide, so that by turning these discs or plates in the one or other
direction partly around their axis by means of a hand lever connected.
therewith, the valve rods, and with them the valves, can be readily
pushed upwards or drawn downwards.
.
It is evident that. by arranging two differently slotted plates on the
same axis and in connection with valve rods leading the one to the inlet
valve and the other to the outlet, the movement of the axis in the one
direction may be made to open or shut one valve while leaving the
other at rest during part of its motion, and vice versa.
It has been found in practise that by these means the unbalanced
slide valves of large steam hammers up to six tons and more may be
readily operated by hand.
Instead of using slide valves both for the inlet and outlet of the steam
below the piston, a slide valve may be used for the inlet, and a piston
valve, ordinary valve, or tap, for the outlet.