Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
SINGI~-B~OW PN~UMATIC PERCUSSIVE T~O~
q`he invention relates to pneumatic percus~i~e tools
used in the construction and mining indu~tries, mechanical
engineering and metallurgy, and more specifically, it deals
with single-blow pneumatic percussive tools.
The invention may be most advantageously used in tool~
designed for marking, center-popping, riveting, marking-out
and gate trimming.
q'he invention may also be used in apparatuses for min-
ing working roof trimming, for demolishing concrete, mak-
in~ holes and performing other operations in the construc-
tion industry.
Pneumatic percussive tool~, in particular, pneumatic
ha~mers al~ used for marking, center-popping, riveting,
marking-out and gate trimming. Depending on a specific ap-
plication, the pneumatic hammer has a working member such
as a ~tamp, center punch or chisel mounted in a ca~ing hav-
ing an interior ~pace. q`he interior space of the casing
accommQdates a hammer piston dividing the interior space
of the casing into an upper chamber and a lower chamber.An
air distribution device is mounted on the casing. An energy
carrier i~ compressed air which i~ supplied to the tool
from a portable or stationary compressor, along a flex-
ible hose. During operation of the tool, the hammer piston
axially reciprocates under the action of a gaseous fluid
under pre~sure admitted to the working chambers through
the air distribution device following the command of the
operator to impart a blow to the end face of the working
, 3~
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member at every working cycle. rlhe working member performs
work under the action of blows whereby, depending on the
type of the working member, marking, center-popping, trimm-
ing or riveting takes place.
Since operations performed by pneumatic hammers are
effected with the direct participation of the operator,such
hammers are to have minimum weight and ~ize.
Known in the art i9 a ~ingle-blo~ pneumatic percussive
tool (cf. USSR Inventor's Certificate No. 946912, Int.Cl.
B 25 D 9/00), comprising a hollow cylindrical casing ac-
commodating a riciprocatable hammer piston and an air dist-
ribution device disposed in a handle mounted on the casing.
'l'he hammer piston divides the casing interior into lower
and upper chambers. The tool alæo has a tube adapted to
establish communication between the lower chamber and gase-
ou8 fluid under pressure at regular intervals.
In this tool, the tube is mounted outside the casing
so that auxiliary devices should be provided outside the
tool. As a result, the size and weight of the tool held
by the operator are increa~ed.
Known in the art i~ a single-blow pneumatic percus~ive
tool (cf. USSR Inventor' 6 Certificate No. 683828, Int.Cl.
B 21 C 51/00), comprising a hollow cylindrical casing ac-
commodating a reciprocatable hammer piston dividing the
interior BpaCe of the casing into upper and lower chambers.
A ~pring-biased valve to which a working member i9 secur-
ed is mounted on the side of the lQwer chamber. An air
distribution deivce having passages and a control lever is
1~90996
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mounted on the side of the upper chamber. A tube ~or sup-
plying gaseous fluid under pressure into the interior space
of the chamber is mounted out~ide the casing.
The arrangement of the tube outside the casing leades
to large size and heavy weight of the tool held by the ope-
rator.
It i9 an object of the invention to reduce size of the
tool.
This object is accomplished by that in a single-blow
pneumatic percus~ive tool com~rising a hollow cylindrical
casing acco~nodating a reciprocatable hammer piston which
divides the interior space of the ca~in~ into an upper chamb-
er and a lower chamber, a spring-biased valve having a work-
ing member secured thereto and mounted on the ~ide of the
lower chamber for establislling com~unicatioll of the lower
chamber with atmosphere at regular intervals, an air dis-
tribution device having passages and a control lever, mount-
ed on the casing on the side of the upper chamber and es-
tablishing communication of the upper chamber with gaseous
fluid under pressure and atmosphere via the passages at re-
gular intervals, a tube for adn~tting gaseous fluid under
pressure to the lower chamber at regular intervals, and a
ratainer for retainin~ the hammer piston in the upper posi-
tion, according to the invention, the hammer piston has an
axial passage and the tube is mounted in this pa~sage and
has an outer shoulder, a continuous internal partition wall
and upper and lower ports provided on either side of the in-
ternal partition wall, a spring-biased air-distribution
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sleeve urged away from the air distribution device is mo-
unted on the tube and has an inner recess, the sleeve be-
ing movable under the action of the hammer piston towards
the upper position in which the ilmer surface thereof cov-
ers the lower ports and being movable under ~he action of
the spring into the lower position defined by the shoulder
in which it establishes communication between the upper
and lower ports via the imler recess for supplying gaseous
fluid under pressure to the lower chamber for moving the
hammer piston upwards.
This construction of the tool makes it possible to mi-
nimize its weight and size because the tube and air dis-
tribution means are disposed inside the tool.
~ he invention will now be described witil reference to
the accompanying drawings showing a specific embodiment
thereof, in which:
Fig. 1 schematically shows a single-blow pneumatic
percusæive tool according to the invention with the hammer
piston in the uppermost position, in longitudinal section;
Fig. 2 schematically ~hows a single-blow pneumatic
percussive tool according to the invention with the hammer
piston in the lowe~nost position, in longitudinal section.
A single-blow pneumatic percussive tool shown in
Figs. 1, 2 comprises a hollow cylindrical casing 1 accommodat-
ing a recip~?ocatable hammer piston 2 which divides the in-
terior space of the casing 1 into an upper chamber 3 and
a lower chamber 4. A spring-biased valve 5 to which is se- `
cured a working member 6 is mounted on the side of the low-
er chamber ~. The valve ~ e~tablishes communication of the
-- 5 --
lower chamber 4 with atmosphere at regular intervals. An
air distribution device 7 having passages 8,9 and 1~ and
a control lever 11 cooperating with a spring-bia~ed spool
valve 12 are mounted on the side of the upper chamber 3. The
upper chamber 3 alternately communicates, via the passagei
8,9,10 o~ the air distribution device 7, with gaseou~ flu-
id under pressure and with atmosphere. An axial passage 13
i8 made in the hammler piston 2 and a tube 14 having an
outer shoulder 15 and a continuous inner partition wall 16
is mounted in this passage. ln this embodiment, the tube
14 is made composite of two tubes of different diameters.
It should be noted that the tube may also be made integral.
'l`he tube 14 has upper port~ 17 above the partition wall 16
and lower ports 1~ below the partition wall 16. An air dis-
tribution sleeve 19 is movably mounted on the tube 14. A
spring 2~ engageable with the air distribution sleeve 20
is mounted on the side of the air distribution device 7.
An inner recess 21 i9 made in the sleeve 19 for establish-
ing ¢o~nunication between the upper and lower ports 17,18
for admitting gaseous fluid under pressure to the lower
ch~mber 4. The hammer piston 2 has a retainer 22 for re-
taining the h~mmer piston in the uppermost position.
q`he single-blow pneumatic percussive tool functions
in the following manner~
Gaseous fluid under pre~sure is admitted through a
socket pipe of the air distribution device 7 (~ig. 1),
spool valve 12, passage 8, upper ports 17, recess 21, low-
1X 9~ ~6
er port~ 18 and tube 14 to the lower chamber 4 and act~upon the h~mmer piston 2 to move the latter to the upper
position. 'l`he hammer piston 2 will move the air distribution
~leeve 19 by its upper end face to compress the spring 2
80 that the sleeve will cover with its i~ner surface the
lower ports 18 and ~aseous fluid under pressure will cease
to get into the lower chamber 4, the h~nmer piston 2 being
retained in the uppermost position by the retainer 22. ~he
upper chamber 3 will thus communicate with atmosphere thro-
ugh the pas~ges 9,1u of the air distribution device 6.
When the valve 5 (~ig. 2) is moved (uepre3sed) into the
interior of the casing 1, the lower chamber 4 communicates
with atmo~phere through the now open valve 5, and gaseous
fluid under pressure iB discharged from the lower chamber
4 into atmosphere. ~Yhen the control lever 11 is depressed
80 as to move the spool valve 1, the passages 8 and 1~ are
shut-off, and ga~eous fluid under pressure is admitted,
via the pa~sage 9, to the upper chamber 3 to act upon the
end face of the hammer piston 2 retained by the retainer
22. As 800n as pressure in the upper chamber re~che~ a pre-
set value, the ha~mer piston 2 is released to rnoYe to the
lower position (~ig. 2). The air distribution sleeve 19
will be moved by the spring 2V to the lowermo~t position
deflned by the ~houlder 15 80 aQ to establish communication
between the upper and lower ports 17, 18 throu~h the recess
21, and ~aseous fluid under pressure is discharged from
the lower chamber 4 through the spring-biased valve 5 into
atmosphere. At the end of travel, the hammer pi3ton 2 de-
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livers a blow at the ~pring-biased valve 5 to which is se-
cured the working member ~ which i8 ill contact with a work-
piece surface to perform useful work. If the tool is lift-
ed above the workpiece surface, the valve 5 is moved by the
spring 23 to the lowermo~t position so a6 to interrupt com-
munication of the lower chamber 4 with atmosphere. When
the control lever 11 is released ~ig. 1), the 8p~01 valve
12 will move so a~ to open the pa6sa~es 8 and 1~, and ad-
mission of gaseous fluid under pres~ure through the pas-
sage 9 is interrupted. I'he upper chamber 3 will communicate
with atmosphere through the passages 9 and 1~. Gaseous flu-
id under pressure is admitted to the lower chamber 4 thro-
ugh the passage 8, upper ports 17, recess 21, lower ports
18 an~ tube 14 to act upon the end face of the ha~ner pis-
ton 2. The hammer piston 2 will start movin~ towards the
upper position under the action of fluid under pressure
on the side of the lower chamber 4. During its movement,
the harnmer piston 2 engages the air distribution sleeve 19
to move lt bo the u~per po~ition and to compre~s the spring
20. ~he air distribution sleeve 19 will cover the lower
ports 18 with its inner surface, and gaseous fluid admis-
sion to the lower chamber 4 is interrupted, and the hammer
piston 2 is retained by the retainer 22. The cycle is then
repeated.
In comparison with prior art ~ingle-blow pneumatic
percussive tools, the tool according to the invention mak-
es it possible to arra~ge the tube and air distribution
means in the interior of the tool thus reducing the tool
siz~ and imprDving its ergDnDmic characteristics.
