Improvements in Apparatus Applicable for Cutting or Chiselling Metal or other Material and Operated by Air or Fluid Pressure.
Year: 1889

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus Applicable for Cutting or Chiselling
Metal or other Material and Operated by Air or Fluid Pressure.
A communication from abroad by FRANZ JACOB LAUN, of Villingen, in the Grand
Duchy of Baden, Empire of Germany, Mechanic."
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.L.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool and 6, Bank Street, Manchester, both in
the County of Lancaster, and 323 High Holborn in the County of Middlesex, Civil
Engineer, 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 :-
Pneumatic tools hitherto in use have, in their present condition, two leading
imperfections:-
1st. When at work, they vibrate so much that they are quite unsuitable for delicate
work, and
2nd. They wear away very rapidly at one side, which arises from the faulty
arrangement of the guide channels or open spacings, and largely diminishes the
practical value of these tools.
In the pneumatic tools forming the subject of this invention, the first of the faults
mentioned is avoided, in that, the chisel holder, after receiving a blow from the
driving piston, is raised again by means of the compressed air, and not, as formerly,
done by means of a spring, and in that the chisel holder is driven further forward by
the blow of the driving piston than the stroke of the latter.
By the employment of compressed air for raising the chiselholder, not only a
shortening of the apparatus and, consequently, a considerable reduction of weight, is
attained, but also above all, any obstacle to the forward movement of the chiselholder
is removed, and thin air cushions are formed between the working surfaces of the
apparatus which prevent damage to these parts. In consequence of these improvo-
ments, not only is the working power very considerably increased, but also so steady
a motion is attained, that the workman guiding the tool with only one hand, can
execute, for instance, the finest engraving in steel.
The prevention of the second fault, the one-sided wear of the driving piston, is
achieved by means of a new and special arrangement of the access or guiding
channels, and open spaces, so that the fresh compressed air always works simulta-
neously and evenly on two opposite sides of the driving piston.
Through this peculiar arrangement of the guiding channels and open spaces, yet a
third advantage is derived, very beneficial to the productive power of the apparatus,
namely, the increase of the stroke of the piston combined with earlier exhaust openings
and the consequent even and quiet movement of the driving piston.
On the annexed drawings are shown in Figures 1, 2, and 3, two longitudinal
sections of the apparatus in two different working positions, whilst
Figures 4 and 5 illustrate details of the apparatus.
Figure 6 is a modification of the form.
In a chamber made direct across the direction of the axis of the driving piston A,
rests a little pusher piston B, which alternately opens and shuts the channels a a' for
the fresh compressed air, and for the exhaust air in the usual manner.
If the
piston has reached its lowest position (Figure 1), the fresh air passes direct through
a little pipe C, channel a, chamber I, channel a', and branch channel cc, indirectly
under the driving piston A. From here the compressed air passes through the central
bore tube d, and angle pipe d' of the chiselholder D under the piston E, fixed in this

page_text: 2
holder. The compressed air now lifts the little piston E, together with the chisel-
holder D and the driving piston A so high that it can escape through the side
opening e in the outside case F of the apparatus. Through this, the chiselholder
reaches sooner the end of its stroke than does the driving piston A. The piston thus
reaches its highest position, (Figure 3). The air contained above the driving piston,
on the upward notion of the latter, passes through channel into chamber , from
here through channel. into the cross boring f1, and then into the groove
(Figure 4) from whence, passing through the length of channel f³, it escapes out of
the bore hole g, (Figure 2) in the outer case F of the apparatus. If the driving
piston A has reached the highest position, the fresh compressed air from the channel a
passes through the small pipe 7, and open space 1 on to the regulating piston B, and
pushes it to the right, whereby the air in front of it escapes through the reserve
space 3, and the small opening 2, into the cross bore hole f, and from there again by
means of the grooves f³, reaches the upper exit g.
The piston is thus guided round, that is, the fresh compressed air passes again
through channel a into chamber ☐, and from here through channel over the
driving piston A: the latter is pressed down, and jerks thus the chisel holder, D,
forward. The air found under the piston escapes at the commencement into the
outside air, through the channel e; as soon, however, as this channel is closed through
the piston E, it (the air) passes through the channels d', d, c, and a', back into
chamber 1, and from there through the channel into the cross borehole f, and
finally reaches the upper exit through the grooves f², f. The chiselholder D
actually, in consequence of its shortened head-piece, springs forward a trifle further
than the driving piston A, of which the stroke is already finished. No hard blow
from the chisel resting on the article to be worked is produced, in consequence of this
springing forward of the chiselholder, and the workman finds no vibration worth
mentioning, so that he can guide the tool with the greatest exactness.
The return guiding of the piston B, when the piston A. is at its lowest position, is
effected by fresh compressed air entering through the opening h, (Figure 1), and the
open spaco 3, behind the guide piston B, and pushing the latter from right to loft,
(Figure 1). Then the air found on the left behind the guide piston passes through
reserve space 2, bore hole ³, and cross bore f', into the groove f, (Figure 4), from
whence it reaches exit 7, (Figure 2) through the groove.ƒ³.
In the arrangement shown in Figure 6, the under part of the apparatus and the
chiselholder are altered in such a way that a considerable simplification of construction
is thereby effected.
The surrounding guide ring of the piston E of the chiselholder D is here omitted,
and replaced by a ring-shaped inner shoulder in the lower part of the apparatus.
The piston E" is made full, and the bore hole is in the above named inner shoulder,
so that the compressed air can again, through it, pass under the piston E, and lift it,
together with the chiselholder D. If the latter be raised high enough to uncover
the side opening e, the air then escapes through this latter: A too long stroke of the
chiselholder is prevented by a thick. string placed underneath the frame of the
apparatus.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent,. I declare that what. I claim is :—
1. In cutting or chiselling apparatus operated by, air or fluid pressure, the
arrangement of a. second piston (E), connected with the chiselholder (D), under
which the compressed air, which raises the driving piston, is conducted in such a
imanner that both the former and the latter are raised before the air can escape from
the exit, for the purpose of insuring a steady working of the apparatus,, substantially
as described.
2. In the chiselling apparatus shown in Figure 1, the arrangement of three open
spaces (1, 2, 3) in the outer wall F of the apparatus, of which two (1 and 2): lie on one

page_text: side, and the third (3) in a mid-position between the other two, but on the opposite
side, whilst above and below the controlling piston valve (B) in the driving piston (A)
are arranged small bore holes h h h h so that fresh compressed air always works
evenly on the two opposing sides of the driving piston and thus prevents an uneven
wearing away of the piston, substantially as described.
Dated this 9th day of August 1889.
WM. P. THOMPSON & Co.,
Agents for the Applicant.