Note: Descriptions are shown in the official language in which they were submitted.
11S7327
The present invention relates to a method of automatic
operation of a percussion apparatus and the percussion apparatus
itself.
The present invention relates more particularly to
a percussion apparatus, a pile driver, especially of the free-
fall type.
Free-fall-type pile drivers normally comprise a
platform on which are mounted a winch and a mast. A pulley
is fixed at the upper end of the mast, a cable wound around
lQ the winch drum passing round the pulley and descending verti-
cally down to a hammer or percussion element supported thereby.
The hammer is of course aligned with the pile or the object
to be struck in order to be driven into the ground. During
the operation, the winch motor operates permanently and the
~perator controls a clutch and a drum brake. Thus, when the
hammer is at the desired height, the clutch is disengaged,
thus allowing the hammer to fall freely and resulting in a
free rotation of the drum. At the moment the hammer contacts
the pile, the operator actuates the brake so as to prevent
2Q continued unwinding of the cable upon sudden stoppage of the
hammer. Immediately after, he disengages the brake and actuates
the clutch so that the winch can drive the drum in the opposite
direction and thus relift the hammer.
There are also known other free-fall-type pile
drivers using for example a crane, the stages of the operation
remaining however the same.
This conventional system suffers from certain draw-
backs,
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for the whole of the operation depends on the operator's
skill. In the first place, the frequency of the operation,
that is, the number of strikes per minute applied to the pile,
depends not only on the possibilities of the machine, but also
on the operator's experience. Moreover, any inattention on
the part of the operator in actuating the drum brake causes
the unwinding of the cable after the stoppage of the hammer,
thus resulting in a highly dangerous si-taation. Likewise,
should the operator actuate the brake too early, the hammer
will be braked before the completion of the strike on the
pile, since the precise moment for stopping the drum is at the
end of the strike, when the pile has accomplished its pene-
tration into the ground.
Only a highly experienced operator can actuate the brake
at the ideal moment, which moment varies according to the
machine, since its action is not instantaneous.
Moreover, the actuation of the brake while the hammer is
still at a certain height of the pile may result in complete
deterioration, through deterioration of the brake or even
through rupture of the cable, which constitutes a great hazard.
Consequently, in order to obtain optimum operation of the
machine, the operator must be highly experienced and skilled
in order to choose the precise moment when he must discontinue
applying the brake and actuate the clutch to relift the hammer
without losing time.
Lastly, the operator must keep the fall height constant,
which height must always be measured with respect to the top
of the pile and, of course, is every time at a lower level.
In practice, it often occurs that, as a result of in-
sufficient brake efficiency or even for the sake of operator's
convenience, the drum is not stopped by actuating the brake but
by actuating the clutch a few moments before the hammer strikes
the pile. This of course results in increased wear of the
clutch, the life of which is thus considerably reduced.
One of the purposes of the present invention is to avoid
one or several abovementioned drawbacks, by providing a per-
cussion apparatus whose operation is entirely automated, thus
making the presence of a highly experienced operator un-
necessary.
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To this end, the invention provides a method of
automatic operation of a percussion apparatus of the type
consisting in letting the percussion element fall, or in
driving the same, onto an object to be struck such as a pile,
a nail, a tube or the like, in order for example to drive it
into the ground, in relifting or displacing the said percussion
element by means of a cable passing round a pulley and connected
to ~a drum, in driving the said drum in rotation by driving
means at least in one direction of rotation, characterized
lQ in that the said percussion element is connected by a mechanical
means to the said drum to form a closed circuit in such a
manner as to cause the stoppage of the drum to substantially
caincide with the moment the strike of the said percussion
element on the said object ends.
Advantageously, the aforementioned mechanical means
of connection are constituted by the cable referred to as a
"return cable".
Thus, at the moment the hammer ends its strike on
the object to be struck and stops, the winch drum is auto-
matically stopped by the return cable.
When such a system is used manually, the operator'sw~ark consists merely in actuating the clutch upon stopping
the drum and in disengaging it when the hammer is suspended
at the required height before its following fall onto the object
to be struck.
Preferably, according to the invention, the operation
of the percussion apparatus is completely automated by the fact
that the stoppage of the drum automatically results in starting
the means for driving the latter in order to relift the per-
cussion element to a predetermined height, and that the heightat which said percussion element is relifted is controlled
by measuring the number of revolutions of the said drum.
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Under such conditions, the operation of the percussion
apparatus is completely automatic and it is sufficient for
the operator to start the operation and then stop it when the
struck object is completely driven in.
Moreover, the invention is also directed to a
percussion apparatus for carrying out the above-described
method of
lQ
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operation, of~etype comprising a driving drum, driving means
for causing the said drum to rotate at least in one direction,
a pulley, a cable referred to as an "operating cable" passing
round the pulley connected to the drum, and to which is
attached a percussion element, characterized in that the per-
cussion element is connected by a second cable, referred to as
a "return cable", to the said driving drum so as to form a
closed circuit in such a manner as to cause the stoppage of
the drum to substantially coincide with the moment the strike
of the percussion element on the object to be struck ends.
According to another charac-terizing feature of the in-
vention, the said closed circuit is obtained by means of a
single cable both ends of which are attached to the said
driving drum, the percussion element being attached to an
intermediate portion of the said cable.
Advantageously, the apparatus according to the invention
comprises means for tensioning the cable or cables. Moreover,
it comprises devices for connecting the aforesaid driving
means for causing the aforesaid driving drum to rotate in a
first direction and for disconnecting the said driving means
after a predetermined rotation of the driving drum in the said
first direction. Thus, the percussion element is relifted to
a predetermined height above the object to be struck. More-
over, the aforementioned connecting and disconnecting means
connect the aforementioned driving means to the driving drum
substantially at the moment the percussion element contacts
the object to be struck.
Advantageously, said driving means and driving drum are
mounted on a winch, and comprise a clutch device allowing the
driving means and the driving drum to be coupled together,
the said clutch device being preferably controlled by the said
connecting and disconnecting means.
Other characterizing features, advantages and details of
the invention will appear more clearly from the following
explanatory description made with reference to the appended
diagrammatic drawing illustrating several forms of embodiment
of the present invention and given solely by way of example
and wherein,
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- Figure 1 is a diagrammatic view illustrating a per-
cussion apparatus according to -the present invention, in its
most usual form ;
- Figures 2 to 5 are diagrammatic views illustrating
various forms of embodiment of a free-fall-type pile driver
according to the present invention ; and
- Figure 6 is a diagramma-tic view of a device for auto-
mating the driving of the drum of the percussion apparatus
according to the present invention.
The device in the Figure illustrates the application
of the method of the invention to any percussion apparatus,
which is not necessarily a pile driver. Indeed, the method of
automatic operation according to the present invention can be
applied to all types of percussion apparatus, whether hydrau-
lic, mechanical or electrical, provided with at least one
winch.
As shown in Figure 1, according to the invention, the
closed circuitof a percussion apparatus comprises a drum 1, a
pulley 2 and a cable 3 wound several times around the drum 1
thereafter passing round the pulley 2 to lastly return onto
the drum 1. At a given point of the cable 3 extending between
the drum 1 and the pulley 2, a percussion element 4 is fixed
so as to strike any body designated by the reference numeral
5.
The cable or the chain 3 may be continuous, it may have
both its ends connected to a percussion element 4, or it may
have both its ends attached to the drum 1. Whatever t~e case,
according to the invention, the circuit formed by the cable is
closed, and any movement of the percussion element 4 results in
a corresponding automatic and forced rotation of the drum 1 and
of the pulley 2, and vice-versa.
Both the drum 1 and the pulley 2 are connected to the
apparatus and the pulley 2 is advantageously acted upon by
resilient means (not shown) which keep the cable 3 under per-
manent tension.
In case the movement of the percussion element 4 is sub-
stantially horizontal, as illustrated in Figure1, andtherefore
there is no free fall of the percussion element 4, the drum 1
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is provided with reversible driving means. Thus, during the
operation, the drum 1 is operated so as to rotate in the
direction of arrow S1, the percussion element 4 being dis-
placed leftward in Figure 1, until a strike is applied to the
body 5. This strike on the body 5 stops the displacement of
the percussion element 4, thus automatically resulting in the
stopping of the drum 1 and the disconnection of the means for
driving the drum 1 in the direction S1. Immediately after,
the drum 1 is actuated by the driving means in the direction
S2 to again move the percussion element 4 away from the body
5. The distance over which the percussion element 4 is moved
away from the body 5 is controlled by measuring the number of
revolutions of the drum 1, and when this number reaches a pre-
determined value, other adequate means reverse the rotation of
the drum 1 to thereafter begin a new cycle.
It should be noted that, in view of the configuration of
the closed circuit, the reaction between the percussion element
4 and the body 5 produces a braking effect on the drum 1, thus
making completely unnecessary the use of a conventional brake.
Moreover, since the distance over which the percussion element
4 automatically moves away from the body 5 is determined by the
number of revolutions of the drum 1, from the moment the per-
cussion element is stopped in contact with the body 5, the
said distance is constant with respect to the position of the
body 5. Stated in other words, the impact of the percussion
element 4 always results from its displacement over a pre-
determined distance.
The apparatus illustrated in Figure 7 has many applications
such as horizontal nailing of iron or other elements, driving
in of tubes, piles or the like into the ground. However, its
main application is a percussion apparatus or pile driver of
the free fall type such as the one illustrated diagrammatically
in Figure 2.
Referring to Figure 2, a pile driver comprises conven-
tionally a platform 6 on which is mounted a winch carrying a
drum 1 and a mast 7 provided at its upper end with a pulley 2
to ensure the rotation of the cable 3.
According to the invention, a second pulley 8 is mounted
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1 157327
at the upper portion of the mast 7 to ensure the rotation and
guiding of the return cable 3 in such a manner as to maintain
vertical the cable portion located below the percussion element
or hammer 9. In the case illustrated in Figure 1, the appara-
tus comprises two cables 3, 3a to form the closed circuit
according to the invention.
The cable 3, referred to as the "operating cable", having
one end attached to the drum 1, is wound several times round
this drum then passes round the pulley 2, has its other end
attached to the upper end of the hammer 9. Likewise, the cable
3a having one end attached to the drum 1 is wound round the
drum in the contrary direction to the winding direction of the
cable 3, and then passes round the pulley 8 and is attached by
its other end to the lower end of the hammer 9.
It is understood that the points of attachment of the cable
to the drum are given by way of example, thus the end of the
cable 3a may be attached to any portion of the hammer without
however departing from the scope of the invention.
Moreover, it is obvious that, as described previously, use
may be made of a single cable 3 wound round the drum 1 and
having both its ends attached to the hammer 9.
Advantageously, the pulley 9 is acted upon by resilient
means (not shown) so as to maintain the cable 3a under tension.
From a mere analysis of Figure 2 it appears that when the
hammer 9 strikes on a pile 10 to be driven for example into the
ground, and when the latter, after having been driven to a
certain depth into the ground, stops the displacement of the
hammer, drum 1 also is simultaneously stopped by the return
cable 3a. In the preferred form of embodiment of the invention,
this stoppage of the drum 1 actuates the clutch of the winch,
whose motor is in permanent opèration, so that the drum 1 is
driven to relift the hammer 9 to the desired height to allow
the following stage of the operation to be carried out. In
other words, after a predetermined number of revolutions of the
drum 1, corresponding to the desired lifting height of the
hammer 9, the clutch is again actuated to disconnect the means
driving the drum 1 to allow the latter to rotate freely. At
that moment, the hammer 9 falls by gravity onto the head of the
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1157327
pile 10, and so on.
Thus, owing to the con-trol of the number of revolutions
of the drum 1 during the relifting of the hammer 9, -the fall-
ing height of the latter is constant with respect to the top of
the pile, independently of the degree of penetration thereof
into the ground. There is thus obtained a pile driver whose
operation is completely automated, which continues to apply
strikes to the pile 10 until the operator stops the system
when the pile has been sufficiently driven into the ground.
One example of the means allowing automatic control of
the r.1eans for driving the drum 1 is illustrated in Figure 6.
It is understood that there exist many means or devices
allowing such automation, the system described hereunder
serving merely to indicate one of those means. The device com-
prises a case 11 within which is mounted shaft 12 supported by
a bearing 13. The end 14 of the shaft 12 is connected by any
appropriate means to the winch of Figure 2, so as to be ro-
tatable jointly with the shaft of the drum 1. The medial
portion of the shaft 12 is provided with a thread15000perating
with a nut 16, the latter being provided with a projection 17
engaged into a straight guiding slot 18 formed on one of the
inner walls of the case 11, in parallel relationship to the
shaft 12. When the shaft 12 rotates, the nut 16 is displaced
axially. The nut 16 is also provided with a second projection
or stop 19 whose function will be explained hereafter.
Moreover,ablock 20 subjected to the action of a spring 21
is mounted in the case 11 on the shaft 12 between the end 14 of
the latter and the thread 15. The distance between the block
20 and the thread 15 is slightly smaller than the thiokness of
the nut 16, so that when the shaft 12 rotates and causes the
nut 16 t~leavethethread 15, the block 20 prevents the nut from
continuing its horizontal displacement and always keeps it
against the starting point of the first turn of the thread 15,
under the action of the spring 21. When the rotation of the
shaft 12 is reversed, the nut 16 can thus again engage the
thread 15 and be displaced leftward (Figure 6).
The case 11 is provided with two electric connections 22
and 23. Connection 23 is connected to the electric contact 24
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" 1157327
of the spring type, whereas the connection 22 is electrically
connected to a shaft 25 parallel with the shaft 12 and to a
second electric contact 26 at the end of the shaft 25. The
shaft 25 can thus perform small displacements towards the left
or the right, so as to separate or join together the contacts
24 and 26, respectively. The end of the shaft 25 is also pro-
vided with a groove 27 which, in the closed position of the
contacts, bears upon a steel ball 28 supported by a spring, the
shaft 25 thus being resiliently maintained in the circuit
closing position.
On the other hand, substantially below the block 20, a
member 29 in the form of a nut adapted to co-operate with the
stop 19 of the nut 17 is mounted on the thread 30 provided on
the shaft 25. This thread also receives a second nut 31 pro-
vided with a lateral projection 32 engaged into a slit 33
formed in another wall of the case 11 in parallel relationship
to the shaft 25.
The end 25a of the shaft 25 is provided with an extension
passing through the wall of the case 11 thus allowing the po-
sition of the nut 31 of the shaft 25 to be controlled, that is,
the axial position of the nut 31 to be modified by merely ro-
tating the button 34.
Likewise, the end 12a of the shaft 12 is provided with an
extension which passes through the wall of the case 11 and ends
with a button 35, so that when the button is pulled outward the
end 14 of the shaft 25 is disconnected from the winch or from
the drum 1, so that it is possible, by rotating this button, to
adjust the initial position of the nut 16.
Thus, with the device illustrated in Figure 6, mounted
in co-operation with the pile driver of Figure 2, the hammer is
first positioned above the pile 10 and bears upon the latter.
By rotating the button 35, the nut 16 is displaced towards the
right in Figure 6 until it leaves the thread 15 and comes into
contact with the member 29, pushing the shaft 25 into the closed
circuit position of the contacts 24 and 26, the sphere 28 being
located in the groove 27. By connecting the winch or the drum
1 and a manual key of the clutch circuit, the winch begins to
wind the operating cable 3, supporting the hammer 9 and simul-
.... ....
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1157327
taneously causes the shaft 12 to rotate, thus causing the dis-
placement of the nut 16 towards the left until the stop 19
comes into contact with the nut 31 of the shaft 25. This con-
tact results in the displacement of the shaft 25 towards the
lef~, ~s s~ating the contacts 24 and 26 and disconnecting the
clutch. The hammer 9, having reached the desired height, then
freely falls onto the pile. Its fall caE;es the shaft 12 to
rotate in the opposite direction and the nut 16 is quickly
displaced towards the right until it comes into contact with
the member 29 at the moment it leaves the thread 15. This
contact on the member 29 again displaces the shaft 25 towards
the right in Figure 6, thus interconnecting the contacts 24 and
26 and again connecting the clutch. It is obvious that, even
with the clutch thus connected, the hammer descends additionally
over a small distance equivalent to the penetration of the pile
into the ground, as a result of the action of the hammer on its
head. However, this distance is relatively reduced and does
not result in an abnormal wear of the clutch. It is of course
obvious that once the nut 16 is adjusted by means of the button
35, at the beginning of the driving in of a given pile, and
the block 20, owing to the spring 21, always maintains the nut
16 applied against the initial turn of the thread 15, the
lifting height of the hammer 9, with respect to the pile head,
is always determined, from the position of the said pile head
at the end of the strike, by the distance between the member 29
and the nut 31 on the shaft 25. This height is of course ad-
justable by rotating the button 34, as was described previously.
It should also be noted that the device described above
and shown in Figure 6 illustrates only one of a number of man-
ners of performing the automation of a pile driver by using the
present invention. It is also possible, for instance, to de-
termine the moment of disconnection of the clutch so as to
make it accurately coincide with the stoppage of the winch
drum 1, i.e. the moment the pile 10 ends its penetration into
the ground, thus completely stopping the hammer 9.
Referring to Figures 3, 4, 5, there will now be described
other forms of embodiment for forming the closed circuit con-
stituted by the operating and return cables of a percussion
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11
1 157327
element or hammer, according to the invention, and usable no-
tably in pile drivers of the free fall type.
In the form of embodiment illustrated in Figure 3, hammer
9 is connected by its upper end to tl~e operating cable 3
passing round a pulley 2 mounted at the top of the mast (not
shown) of the pile driver, the other end of the said operating
cable being connected to the shaft of a pulley 35 so as to
support the latter. Moreover, the cable 3 passes round a guide
pulley 36. The hammer 9 is also connected to the return cable
3a which passes round the pulley 8 attached to the bottom
portion of the mast, and after passing round the guiding pulley
37, is connected to the shaft of the pulley 38 so as to support
the latter. As appears from this Figure, pulleys 38 and 35 are
therefore movable and their displacement depends upon the dis-
placement of the end of the operating and return cables 3 and
3a, respectively, connected to the hammer. The displacement of
these pulleys is adjusted and controlled by a third cable 39
and a fourth cable 40, respectively, having one of their ends
connected to fixed points 41 and their other end attached to
the driving drum 1 of the pile driver. In the preferred form
of embodiment of the invention, the drum 1 is connected to a
device for automating the operation of the pile driver. On the
other hand, according to the invention, the third and fourth
cables ~9 and 40 are wound round the drum 1 in opposite direc-
tions. Thus, the closed circuit according to the invention is
constituted by the cable 39, the operating cable 3, the return
cable 3a-and the cable 40. This form of embodiment is par-
ticularly advantageous when the hammer 9 is of great weight.
In another form of embodiment illustrated in Figure 4, the
pile driver comprises two drums 1, 42. Drum 1 is referred to
as the "driving drum" for it is driven and connected to the
driving means controlled by the automating device according to
the invention, whereas the drum 42 is a conventional drum for
winding the hammer operating cable. In this form of embodiment,
the operating cable 3 connected to the hammer 9 passes round a
pulley 35a so as to support the latter, and round guiding
pulleys 36, and is wound onto the drum 42 The shaft of the
pulley 35a is connected to the shaft of the pulley 35, in such
a manner that these two pulleys are movable jointly. In other
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1 157327
words, when the pulley 35 is displaced upwards, the pulley
35a is also displaced upwards, or vice-versa. The thus
assembled pulleys 35, 35a define a movable block 43. In a
manner similar to the foregoing form of embodiment, a third
cable 39 having one end attached to a fixed point 41 and its
other end attached to the automated drum 1 passes round the
pulley 35 so as to control the displacement of the movable
block 43. The circuit is closed by the return cable 3a wound
in the opposite direction to the direction of winding of the
cable 39 on the drum 1 and connected to the hammer 9.
In another variant of embodiment illustrated in Figure 5,
and usable notably for bottom striking during the driving of a
tube 44 into the ground, and comprising a hammer 9 penetrating
into the tube in order to compact the earth at the lower por-
tion of the latter and a striker 45 striking on a damper 46
placed at the end of the tube 44 to drive the latter into the
ground. The movable block 43 comprises two pulleys 35a round
which pass the cables 3 for operating the hammer and striker
45. In this apparatus, it is obvious that the return cable 3a
is attached to the striker and not to the hammer 9. However,
since the striker and the hammer 9 moye in synchronism, the
operation of this form of embodiment is in conformity with the
present invention. Advantageously, the operating cable 3 of
the striker and the return cable 3a may be constituted by a
single cable, and in this case the striker is attached to an
intermediate portion of the said cable.
Thus, the present invention provides a percussion apparatus
whose operation is automated, allowing the drum 1 to be stopped
when the percussion element is stopped on the element to be
struck. Such automatic stoppage of the drum allows the wear of
the elements of its clutch mechanism to be reduced.
Moreover, the productivity of a percussion apparatus ac-
cording to the present invention is considerably increased
even when the latter is used by fairly skilled operators.
Another advantage of the invention resides in the fact that
the time necessary for the installation and starting of a per-
cussion apparatus according to the invention is very short,
thus reducing investments, compared notably to the diesel ham-
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13
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mer used heretofore.
Of course, the invention is by no means limited to theforms of embodiment described and illustrated which have been
given by way of example only. Thus, thoæ various forms of em-
bodiment may be combined according to the use of the per-
cussion machine.
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