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The present invention relates to a machine for pounding
and grinding materials in general, in particular on a
wooden base, in simple or aggregate form.
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Machines for pounding and grinding materials in
general, such as for example on a wooden and non-wooden
base, are known. Although their operation is quite good
in normal conditions, in these machines of the prior
art technical problems may arise in the presence of
particularly hard bodies, such as for example metal
bodies, accidentally introduced into them, or in the
presence of bridging of material inside them.
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In fact, if a hard body - such as a metal bar or else -
is even accidentally introduced, the latter is brought
into contact with the cutting and crushing disks and
causes a great disturbance or even serious problems.
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If the hard body is of extremely small shape and
dimensions, generally there are no problems, but if the
same is quite large, it may interfere with the pounding
and grinding elements, thus breaking them or causing
connected parts of the machine to deform. Therefore, it
is necessary to consequently stop the entire machine,
manually remove the foreign body, and proceed to repair
the damaged parts or, in case, to replace them, if
irremediably damaged.
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This fact implies switching the machine off, carrying
out manual interventions of personnel, who if needed
shall be skilled personnel, and an overall cost which
may be hard to sustain.
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Furthermore, as already said, bridging of material may
form during the operation of the machine, which slows
down the machining and may imply that the machine be
switched off, as it is almost impossible to
continuously feed the material to be pounded and
ground.
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Also in this case, known machines must be switched off,
and the bridging of material must be manually broken
and removed. Although quite easy, also this operation
implies a loss of time and of productivity.
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Furthermore, in both cases a manual intervention in the
machine can be dangerous for the operator, even if the
machine is stationary.
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Therefore, object of the present invention is that of
solving the technical problems mentioned above by
providing an automation of the machine for pounding and
grinding materials, in particular on a wooden base.
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Another related object of the present invention is that
of providing a machine of extreme constructive
simplicity, which would therefore be easy to realise by
the operator in charge.
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A further object of the present invention is that of
providing a machine that would automatically discharge
undesired bodies and break possible bridging of
materials.
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In view of the objects mentioned above, according to
the present invention, a machine has been devised, for
pounding and grinding materials in general, for example
on a wooden base, in simple or aggregate form, having
the features described in claim 1 and in the further
claims herewith enclosed.
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The structural and functional features and advantages
of the present invention with respect to the prior art
will appear more clearly from an examination of the
following description, made with reference to the
attached drawings, which show an example of machine
realised according to the invention. In such drawings:
- Figure 1 shows a schematic front section of the
machine for pounding and grinding materials in general,
in a first operating step of normal work,
- Figure 2 shows a top plan schematic view of the
machine of Figure 1,
- Figures 3-5 show sections similar to those of Figure
1 in different operating steps,
- Figures 6 and 7 show sections of two further
alternative exemplifications of the machine with two
movable and detachable bearing structures.
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With reference to the drawings, according to the
present invention, a machine for pounding and grinding
materials in general, for example on a wooden and non-wooden
base, in simple or aggregate form, is as a whole
referred to with reference numeral 10.
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In the following description, it will be noted that the
machine is particularly intended for pounding and
grinding materials on a wooden and non-wooden base. A
machine of this type will be provided with self-diagnostic
characteristics for the purpose of being
completely automated in any of its operating steps,
thus being adapted to face the most frequent defects.
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In the exemplificative embodiment shown, machine 10 for
pounding and grinding wood according to Figure 1 is
made up of an upper loading portion, or hopper 11,
arranged on a frame 35, at the base of which there are
arranged baffle devices 12 for intercepting the
material to be pounded and ground in feeding.
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In its central portion, machine 10 comprises a portion
where the material is machined, made up of two counter-rotating
shafts 13 on which there are engaged arrays of
cutting and crushing disks 14, provided with a suitable
profile adapted for grinding. The shafts can also be
four or more. In the lower portion, the machine is
provided with a discharge portion 15, which is
associated and put into communication with a conveyor
unit 16 for discharging the pounded and ground
material.
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From a more detailed examination, it can be noted that
in the example, in the central machining portion, a
pair of bearing structures 17 is provided, in the shape
of two half bearings supporting the two shafts 13, that
is to say, the driving unit of the same shafts. The two
bearing structures 17 are hinged in 18 to a bedplate 19
of the machine itself. In fact, said constructive
special feature allows - by means of actuators, such as
hydraulic cylinders 20, hinged at their ends in 21 to
bedplate 19, and in 22 to the bearing structures 17 -
causing a rotation of the bearing structures or half
bearings 17 such as to free a lower aperture 23 of the
machine, thus making the self-cleaning cycle start, as
it will be explained hereafter.
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In fact, actuators 20 cause the bearing structure 17 to
pivot from a faced position and a distanced position at
the sides of the central portion.
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As it is evident, the rotational motion is transmitted
to shafts 13 through motors 24, of the hydraulic or
electric type, associated to a reduction gear and/or to
a torque limiter 25, as schematised. Pairs of motors 24
with relevant reduction gears or torque limiters at
both ends of shafts 13 can be provided for limiting the
torsions on shafts 13.
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Inside the bearing structures 17, facing the cutting
and crushing disks 14, alternated between them, fixed
cutting blades 26 integral with the bearing structures
17 are provided.
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There is also provided a locking unit 27, for example
of the hydraulic/mechanic type, which makes the two
bearing structures 17 integral with each other during
the working step and frees them during the cleaning
step.
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The upper mobile members of the machine, that is,
baffles 12, are moved by at least one cylinder 28, near
hopper 11, from each side. Cylinder 28 operates a
leverage 29, which in turn determines the movement of a
rack rod 30, pivoted at one end in 31 to the respective
baffle 12. Baffles 12 are pivoted in 34 to hopper 11.
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When the machine is in the condition illustrated in
Figure 1, the material to be ground is arranged in the
loading portion, that is, into the hopper. The baffle
devices 12 in this step are closed against the walls so
as to allow the feeding of the material to the central
machining portion, that is to say, to the pounding -
grounding portion.
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In this intermediate portion, the particular
arrangement of the cutting and crushing disks 14, their
profile, together with the difference of the directions
of rotation of shafts 13 and their different angular
velocity, as well as the presence of the fixed cutting
blades 26, allow an optimum machining of the material.
In fact, there will be a combined action of cutting and
tearing made even more efficient by the above-mentioned
difference of rotational regimes. Thus, the slow shaft
defines a sort of braking effect on the material, and
said effect allows an efficient grinding action to the
array of disks 14 mounted on the fast-rotating shaft.
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The speeds of rotation can be varied in function of the
productivity required of the machinery, and in function
of the typology of material to be treated.
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For the purpose of ensuring a lasting and effective
use, the machine is provided with a self-diagnosis and
self-stop device to prevent possible operation
anomalies.
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In fact, two conditions of automatic machining stop are
provided to face the following unexpected occurrences:
- a - the presence of ferrous and non-ferrous material,
such as a bar 32, of large dimensions in the grinding
portion, which causes an abnormal cutting stress.
- b - self-generation of bridging by the material.
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In fact, should a hard element, such as a bar 32,
proceed beyond a possible interception portion, drum,
magnetic plate or gravity trap (not shown), or should
it accidentally come into the charging mouth and
arrange between disks 14, as shown in Figure 3, it
could cause anomalies and malfunctioning, or it could
even cause the system to break down.
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To overcome this problem, the machine being examined is
provided with a device for limiting the transmitted
torque, such as for example a viscous joint 25,
connected to a driving unit 33, such as for example a
control gearcase.
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When the machine is in the condition of operating under
excessive stress, since the resisting action of the
foreign body 32 is such as to overcome the cutting
action of disks 14, motors 24 lean towards a dangerous
instability condition, and the driving unit 33 starts.
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Said unit or gearcase 33 operates according to the
following steps. In a first step, the direction of
rotation of shafts 13 reverses for a portion of turn or
for some turns so as to move the hard foreign body 32
away from disks 14 and, after a fixed interval of time,
the former direction of rotation is restored to attempt
crushing the resisting body 32.
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In a second step, the first step is carried out for n
attempts and, if after said operation the machine has
not been capable of crushing the hard metal piece 32,
said attempt stops. In fact, at this point, having
assessed that for n times it has not been possible to
pound or grind the foreign body, attempt is made to
discharge it from the machine body.
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In this case, the direction of rotation of shafts 13 is
reversed with respect to the operating condition, for
at least one turn, only after the driving unit 33 has
provided for making cylinders 28 and thus, rack rod 30
rotate. This movement brings the closing baffles 12 to
a position of material blocking, as in Figure 4. Once
the material has been blocked in the hopper 11, the
self-moving bearing structures 17 of the machine are
released through the actuation of the blocking unit 27.
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At this point, it is possible to actuate the lifting
cylinders 20 for the purpose of removing the bearing
structures 17 with the relevant shafts 13 and the
rotating disks 14 from one another, as well as the
fixed cutting blades 26. With this removal, a discharge
light is defined, from which - thanks to the combined
action of force of gravity and of the normal direction
of rotation of shafts 13 - it is possible to let the
element 32 fall down, which element had caused the
disturbance to the grinding cycle. In this case, in
fact, said element 32 which was inside the machine
during the self-cleaning cycle, will settle on a
conveyor belt 16, arranged below the machine, which in
turn reverses its motion, and ends its stroke in a
special discharge member or container.
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Once the cleaning cycle has ended, the machine returns
to its operating condition, through the driving unit
33, by first moving cylinders 20 to rest condition, and
then continuing the normal motion of shafts 13.
Afterwards, baffles 12 close against the walls through
cylinders 28 and leverages 29 with the relevant rack
rod 30.
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Associated to the problem of the intrusion of iron into
the material to be ground, the possibility of a self-generation
of bridging of materials has to be taken
into account, which may bring to a drop in production.
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Also in this case, the machine is programmed for
overcoming problems of this kind.
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In fact, a self-diagnosis and self-cleaning cycle
assimilable to the previous one is carried out.
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Should a bridging of material form, in absence of
material to be pounded, the absorption of motors 24
would suddenly decrease. A special detector for
controlling the absorptions in the driving unit 33
indicates the anomaly and actuates a subsequent step.
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In this second step, the operating direction of
rotation as regards disks 14 is kept unaltered; the
lifting cylinders 20 stay in a rest configuration;
cylinders 28 connected to baffles 12 are actuated for a
fixed number of times n to attempt moving the material
that has formed the bridging through the action of the
same baffles, as shown in Figure 5.
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Then, after n strokes, cylinders 28 return to such
position as to close baffles 12 against the walls of
hopper 11, and the machine resumes its working cycle.
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Should there still be a low absorption, after a preset
time of idling operation, the machine enters into alarm
and stops. Now, a manual intervention is necessary for
checking whether the bridging is still present and the
feeding material is lacking. Once checked and restored,
the machine can restart.
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Thanks to these self-diagnostic devices, the machine is
totally automated in any operating step, and it is
capable of coping with the most frequent anomalies.
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Figures 6 and 7 show two further exemplifications of
embodiment of the machine of the invention in which,
where possible, the same reference numerals are used.
In these illustrations, it can be noted that the
bearing structures 17 can be alternatively moved being
driven by two sliding wheels 40 onto planes 41 integral
with bedplate 19 or onto further inclined planes 42
according to a preselected angle. The translation is
driven by actuators 20, and it allows disengaging the
rotating disks 14, as partly shown in the drawing. All
of the above using the same inventive principle.
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The problems of the prior art have thus been solved.
