IMPROVEMENTO TAY DID RO AGUTINE. HURD LETT IA LOUIENES BAD DIVET
Year: 1883

page_text: LETTERS PATENT to Ralph Hart Tweddell of Delahay Street Westminster
in the County of Middlesex, James Platt and John Fielding both of the
Atlas Engine Works Gloucester in the County of Gloucester for an Invention
of IMPROVEMENTO TAY DID RO
AGUTINE. HURD LETT IA
LOUIENES BAD DIVETTIVA
PROVISIONAL SPECIFICATION left by the said Ralph Hart Tweddell,
James Platt, and John Fielding at the Office of the Commissioners of Patents
on the 3rd February 1883.
RALPH HART TWEDDELL of Delahay Street Westminster in the County of
Middlesex, JAMES PLATT and JOHN FIELDING both of the Atlas Engine Works
Gloucester in the County of Gloucester " IMPROVEMENTS IN DIRECT ACTING
HYDRAULIC MACHINES FOR RIVETTING, PUNCHING, FORGING AND SUCH LIKE
OPERATIONS
"
Our invention relates to means of varying the power of direct acting hydraulic
machines employed for rivetting, punching, forging and such like operations, so
that their tools can be applied with more or less force according to the nature of
the work to be done. For this purpose, we provide the hydraulic cylinder of the
machine with a differential plunger, and with suitable valves so that the fluid
pressure can be made to act either on the smaller area of the plunger or on its
annular area or on both areas, the force with which the plunger carrying the tool
is advanced being thus capable of three variations. In order to provide for varia-
tions between those that are thus determined, we, in some cases connect to the
moving plunger a lever against which abuts the plunger of another or auxiliary
cylinder, and we mount this cylinder on a.trunnion, so that its plunger can be
directed against the lever nearer to or farther from its fulcrum, thus aiding less or
or more the differential plunger to which the lever is connected. Or, otherwise, the
position of the fulcrum of the lever may be shifted, the auxiliary cylinder being
fixed in position, but its plunger acting with greater or less leverage the farther
from it or the nearer to it the fulcrum of the lever is placed. In cases where
rivetting machines are made with additional plungers for closing together the plates
to be rivetted as described in the Specification to Letters Patent granted to us ou
D

page_text: the 10th November 1880 N° 4609, we utilise the area of the additional plunger for
giving additional force to the rivetting tool as it is completing its stroke in the
following manner. The plungers being advanced as described in the Specification
above referred to so that the one presses the plates together, when it stops, the
rivetting plunger continuing to advance causes discharge of fluid from behind the
closing plunger, and therefore acts with a force depending on the difference of the
areas of the rivetting and the closing plungers, but as the tool is completing the
rivetting operation, we open discharge from behind the closing plunger and thus
relieve the rivetting plunger from the counterpressure due to the area of the
closing plunger, so obtaining the pressure due to the whole area.
A convenient construction of rivetting machine to act in this way is the
following. On the frame of the machine we fix a plunger. having such area that
the available pressure acting on it will give the maximum force required. To this
plunger is fitted a cylinder which carries at its end the rivetting tool, and which
may be termed the rivetting cylinder. This cylinder is bored centrally to receive
a plunger considerably less in area than the fixed plunger above mentioned. This
smaller plunger, working in the bore which may be termed the closing cylinder,
carries at its end the closing tool which is in the form of a fork having a limb on
each side of the rivetting tool. At the side of the smaller plunger there is a still
smaller plunger for effecting the back stroke of the tools, working in a stationary
cylinder which may be termed the push-back cylinder. The hydraulic connections
to these three cylinders are thus arranged. The small push-back cylinder is
always in communication with the pressure reservoir or accumulator, so that the
pressure on its plunger can push back the rivetting cylinder and the closing
plunger when the former is relieved from the hydraulic pressure. The rivetting
cylinder is provided with valves by which it can be made to communicate either
with the pressure reservoir or with the free discharge. The closing cylinder can
also be made to cominunicate with the pressure reservoir or the discharge, or its
outlet can be entirely closed. In rivetting with this machine, the pressure is in
the first place allowed to act in both the rivetting and closing cylinders, the closing
tool presses the plates together and the rivetting tool upsets the rivet with the
force due to the excess of the area of the rivetting cylinder over that of the closing
cylinder. On now opening the discharge from the closing cylinder, the rivetting
cylinder is relieved from the back pressure due to the area of the closing cylinder,
and consequently the force applied to the rivetting tool is that due to the full
area of the rivetting cylinder. The rivetting being completed, the rivetting
cylinder is opened to discharge and thereupon, the push-back plunger effects the
backstroke of both the rivetting and the closing tools. When only a moderate
rivetting force is required, and closing is unnecessary, the rivetting tool may be
fixed instead of the closing tool on the closing plunger which can effect the
rivetting, the large rivetting cylinder remaining stationary.
Although we have described the cylinders and plungers arranged in a compact
form, it is obvious that they might be arranged otherwise to operate in the
manner described. For example, the rivetting cylinder might be stationary in the
frame, and fitted with a trunk plunger which carries the rivetting tool and has its
trunk encircled by an annular plunger carrying the closing tool.
In order to economise the high pressure liquid employed, we make the rivetting
cylinder communicate by a passage governed by a check valve with the discharge
cistern and we connect the closing plunger to the rivetting cylinder by side links.
At first we admit fluid under pressure only to the closing cylinder, and its
plunger advancing to effect closing of the plates, draws with it the rivetting
cylinder which becomes filled with low pressure liquid. We then admit liquid
under high pressure to the rivetting cylinder thus effecting the rivetting as above
described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Ralph Hart Tweddell, James Platt, and John Fielding in the
Great Seal Patent Office on the 1st August 1883.
RALPH HART TWEDDELL of Delahay Street Westminster in the County of
Middlesex, JAMES PLATT and JOHN FIELDING both of the Atlas Engine Works
Gloucester in the County of Gloucester "IMPROVEMENTS IN DIRECT ACTING
HYDRAULIC MACHINES FOR RIVETTING, PUNCHING, FORGING AND SUCH LIKE
OPERATIONS
"
Our invention relates to means of varying the power of direct acting hydraulic
manchines for rivetting, punching, forging and such like operations, so that their
tools can be applied with more or less force according to the nature of the work to
be done. For this purpose, we provide the hydraulic cylinder of the machine with
a differential plunger and with suitable valves, so that the fluid pressure can be
made to act either on the smaller area of the plunger or on its annular area, or on
both areas, the force with which the plunger carrying the tool is advanced being
thus capable of three variations.
Fig. 1 of the accompanying drawings is a section partly in elevation of the head
of a hydraulic rivetting machine with one arrangement according to our invention
for varying the power, Fig. 2 is a front view The plunger A is made differential so
that the pressure can be made to act only on the annular area B, or by opening
a valve C, it can be made to act on both the annular area and the circular end
area D. The head E of the plunger which carries the rivetting tool is made
eccentric so that, when the cylinder G is unscrewed from its place, and the draw
back cylinder F is withdrawn, the plunger and head can be lowered sufficiently far
to allow the head E to pass under the upper part H of the frame. By this con-
struction, we are enabled to make the plunger and head in one piece. By providing,
as shewn in Fig. 3, stop valves C and C¹ for both areas D and B we can apply the
pressure on the annular area B, or on the end area D or on both together. The
cylinder and plunger presenting variable area may be constructed as shewn in
Fig. 4, the draw back being effected by a rod I. It is of advantage to make a
communication provided with a check valve, as shewn at K, from either or both
parts of the cylinder to a low pressure cistern, so that when the one area of the
plunger is used for the working pressure, water can flow freely into the other.
Thus, assuming that the plunger has made part of its forward stroke subject to
pressure on one of its areas, the power can be increased by causing the pressure
also to act on its other area, without waste of high pressure liquid. Fig 5 is a
section shewing another construction of differential cylinder and plunger, the
cylinder in this case being the moving part while the plunger is stationary. The
parts in this figure corresponding with those in Fig. 1 are marked by similar
letters.
In order to provide for variations between those that are thus determined, we,
in some cases, connect to the moving plunger a lever against which abuts the
plunger of another or auxiliary cylinder, and we mount this cylinder on a trunnion,
so that its plunger can be directed against the lever nearer to or farther from its
fulcrum, thus aiding less or more the differential plunger to which the lever is
connected.
Fig. 6 is an elevation partly in section of the head of a hydraulic rivetter with
an auxiliary cylinder with plunger L. The cylinder is mounted on a trunnion and
the plunger can be made to bear against a curved lever M nearer to or farther from

page_text: its fulcrum according as less or greater power is required to assist the main working
plunger. By reversing the position of the auxiliary cylinder and lever, as indicated
by the dotted lines, the plunger L may be used to oppose more or less the main
plunger, and to operate the draw back. The attitude of the auxiliary cylinder
may be shifted by means of a worm and toothed segment N or other convenient
gearing. Or, otherwise, the position of the fulcrum of the lever may be shifted,
the auxiliary cylinder being fixed in position, but its plunger acting with greater
or less leverage the farther from it or the nearer to it the fulcrum of the lever is
placed.
Fig. 7 shews an arrangement of this kind, the auxiliary cylinder being in this
case fixed in position, but the lever M and the framing of the machine being
provided with a number of holes into any of which the fulcrum pin O can be
inserted so as to alter the leverage with which the auxiliary plunger L acts in aid
of the main plunger.
In cases where rivetting machines are made with additional plungers for closing
together the plates to be rivetted, as described in the Specification to Letters
Patent granted to us on the 10th November 1880 N° 4609, we utilize the area of
the additional plunger for giving additional force to the rivetting tool as it is
completing its stroke in the following manner. The plungers being advanced, as
described in the Specification above referred to, so that the one presses the plates
together, when it stops, the rivetting plunger continuing to advance causes
discharge of fluid from behind the closing plunger, and therefore acts with a force
depending on the difference of the areas of the rivetting and the closing plungers;
but, as the tool is completing the rivetting operation, we open discharge from behind
the closing plunger and thus relieve the rivetting plunger from the counter
pressure due to the area of the closing plunger, so obtaining the pressure due to the
whole area.
A convenient construction of rivetting machine to act in this way is shewn by
the longitudinal section Fig. 8. On the frame of the machine we fix a plunger P
having such area that the available pressure acting on it will give the maximum
force required. To this plunger P is fitted a cylinder Q which carries at its end
the rivetting tool 9 and which may be termed the rivetting cylinder. This cylinder
is bored centrally to receive a plunger R considerably less in area than the fixed
plunger P. This smaller plunger R working in the bore R¹ which may be termed
the closing cylinder, carries at its end the closing tool r which is in the form of a
fork having a limb on each side of the rivetting tool, as shewn in elevation Fig. 9.
At the side of the smaller plunger R there is a still smaller plunger S, for effecting
the back stroke of the tools, working in a stationary cylinder T which may be
termed the push back cylinder. The bydraulic connections to these three cylinders
are thus arranged. The small push-back cylinder T is always in communication
with the pressure reservoir or accumulator, so that the pressure on its plunger can
push back the rivetting cylinder Q and the closing plunger R when the former is
relieved from the hydraulic pressure. The rivetting cylinder Q is provided with
valves U of ordinary construction, by which it can be made to communicate either
with the pressure reservoir or with the free discharge. The closing cylinder R¹
can also be made to communicate with the pressure reservoir or the discharge, or
its outlet can be entirely closed.
Fig. 10 is a sectional plan to an enlarged scale of the valves for this purpose.
vis the high pressure supply and w is the discharge and x is a check valve which
allows passage from the cylinder R¹ back to the high pressure supply.
In rivetting with this machine, the pressure is in the first place allowed to act
in both the rivetting and closing cylinders Q and R'; the closing tool presses the
plates together, and the rivetting tool q upsets the rivet with the force due to the
excess of the area of the rivetting cylinder Q over that of the closing plunger R.
On now opening the discharge from the closing cylinder R¹, the rivetting cylinder
is relieved from the back pressure due to the area of R', and consequently the force
applied to the rivetting tool q is that due to the full area of the rivetting cylinder Q.

page_text: The rivetting being completed, the rivetting cylinder Q is opened to discharge by
means of the valve U, and thereupon the push-back plunger S effects the back-
stroke of both the rivetting and the closing tools q and r. When only a moderate
rivetting force is required, and closing is unnecessary, the rivetting tool q may be
fixed, instead of the closing tool r, on the closing plunger R which can effect the
rivetting, the large rivetting cylinder Q remaining stationary.
Although we have described the cylinders and plungers arranged in a compact
form, it is obvious that they might be arranged otherwise to operate in the manner
described. For example, the rivetting cylinder might be stationary in the frame,
and fitted with a trunk plunger which carries the rivetting tool and has its trunk
encircled by an annular plunger carrying the closing tool, the cylinders being in
this case arranged as shewn in Fig. 4.
In order to economise the high pressure liquid employed, we make the rivetting
cylinder communicate by a passage governed by a check valve with the discharge
cistern, and we connect the closing plunger to the rivetting cylinder by side links.
At first we admit the fluid under pressure only to the closing cylinder, and its
plunger advancing, to effect closing of the plates, draws with it the rivetting
cylinder which becomes filled with low pressure liquid. We then admit liquid
under high pressure to the rivetting cylinder, thus effecting the rivetting as above
described.
Fig. 11 is a longitudinal section shewing this arrangement, the rivetting
cylinder being connected to the closing plunger R by side links. As the plunger R
advances to press the plates together it draws forwards the cylinder Q, and water
enters Qby the check valve K from a low pressure supply, so that when the water
at working pressure is admitted to act on Q for the purpose of rivetting, there is
no empty space for it to fill up in Q.
Having thus described the nature of our invention and in what manner the
same is to be performed, we claim, in respect of direct acting hydraulic machines
for rivetting, punching, forging and such like operations:-
First. Constructing the cylinder and plunger with a circular and an annular
area in combination with stop and check valves, so arranged that the working
pressure can be made to act on either area or both, substantially as and for the
purposes herein set forth with reference to Figs. 1, 2, 3, 4 and 5 of the accompanying
Drawings.
Second. In combination with the main working cylinder and plunger, an
auxiliary cylinder and plunger arranged to act with variable leverage, substantially
as described with reference to Figs. 6 and 7.
Third. The method, substantially as herein described with reference to Figs. S,
9, 10 and 11, of effecting closing of plates and rivetting by successive stages of
force, first a force suitable for closing, then a force suitable for upsetting the rivet,
and finally an increased force force for completing the rivetting operation.
Fourth. The construction of rivetting machine with closing and rivetting tools
operating separately and in conjunction, substantially as described with reference
to Figs 8, 9, 10 and 11
In Witness whereof We the said Ralph Hart Tweddell and James Platt
have hereunto set our hands and seals this Thirtieth day of July in the
year of our Lord One thousand sight hundred and nighter thone