Self-propelled crushing machine

Details Self-propelled crushing machine Self-propelled crushing machine

2001-08-31

2002-11-05

Rosenbaum, Mark (Department: 3725)

Solid material comminution or disintegration

Apparatus

With automatic control

C241S101761

Reexamination Certificate

active

06474577

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a self-propelled crushing machine for crushing thrown rocks, concrete, woods and the like and discharging to an outer portion.
BACKGROUND OF THE INVENTION
There exist various kinds of self-propelled crushing machines for crushing rocks, for crushing concrete, for crushing woods and the like. For example, the self-propelled crushing machine for crushing woods has, as shown in
FIGS. 1 and 2
, a rotary crusher
1
and a rotary tub
3
which introduces a wood
2
thrown from an outer portion to the rotary crusher
1
due to a rotation on a self-propelled truck
4
, crushes the wood
2
introduced from a rotary tub
3
to the rotary crusher
1
and discharges to the outer portion. The details are as follows.
The rotary crusher
1
is a so-called hammer mill. This has a plurality of cutters
1
b
on an outer periphery of a shaft
1
a
which is structured to be made rotatable by crusher drive means, and crushes the wood
2
by the cutters
1
b
. The crusher drive means is driven by an oil hydraulic pressure, directly driven or the like.
The rotary tub
3
has a funnel
3
b
which is made rotatable by the tub drive means on a fixed bottom plate
3
a
. A part of the fixed bottom plate
3
a
is open, and the cutters
1
b
of the rotary crusher
1
can be overviewed from the opening. The tub drive means is also of an oil hydraulic driven type, a direct driven type or the like.
When throwing the wood
2
having a long size into the rotary tub
3
, a lower end of the wood
2
is brought into contact with the upper portion of the fixed bottom plate
3
a
and the cutters
1
b
within the opening. On the contrary, the wood
2
falls down and an upper side surface thereof is brought into contact with an inner wall of the funnel
3
b
. A plurality of convex portions are provided on the inner wall of the funnel
3
b
in a vertical direction, and the convex portion presses the wood
2
due to a rotation of the funnel
3
b
. As a result, the lower end of the wood
2
reciprocates between the upper portion of the fixed bottom plate
3
a
and the cutter
1
b
while the wood
2
changes an attitude thereof, so that even the long wood
2
can be crushed by the cutters
1
b
. The crushed wood
2
is used for a pulp raw material, a manure, a fuel and the like.
In this case, the self-propelled crushing machine is structured such that when the raw materials are large or hard, or when they are mixed with the small raw materials or the soft raw materials, a load of the crusher is increased, a rotational speed is reduced, and a crushing efficiency is lowered. The reduction of the rotational speed causes a breakage of the crusher. Then, there is a structure made such as to automatically stop a raw material supply apparatus (the rotary tub
3
in the case of being used for crushing the wood) when the rotational speed of the crusher is lowered to a predetermined value Nb, and to automatically start the raw material supply apparatus when the rotational speed of the crusher is inversely increased to a predetermined value Na. In this case, in order to prevent the automatic stop and the automatic start from generating a hunting, a relation between the predetermined values Na and Nb is set to, for example, a relation Na>Nb+50 rpm.
However, the prior art mentioned above has the following problems.
(1) Since the raw material supply apparatus is automatically started or automatically stopped in accordance with a rotational change of the crusher, there is no function for automatically returning the crusher to a normal rotation although the reason of breaking the crusher is solved. Accordingly, a reduction of a crushing efficiency is unavoidable.
(2) A crushed grain size (a piece size in the case of the crusher for crushing the wood) becomes finer as the rotational speed of the crusher becomes higher. If the normal rotational speed of the crusher is set to Ns, a relation Ns>Na and Ns>Nb is established. In this case, since the relation Na>Nb is established as mentioned above, the changing range of the rotational speed of the crusher becomes wide to Ns to Nb. Accordingly, it is hard to obtain the crushed material having a fixed grain size.
(3) In particular, the self-propelled crushing machine for crushing the wood has the rotary tub, however, there has not been suggested a technique structured such as to preferably control the rotational speed and perform a crushing having a higher efficiency.
(4) The start and stop of the rotary tub depend only upon the rotational change of the crusher, and the rotary tub itself does not have an automatic control function. Further, the breakage of the crusher is indirectly prevented by the automatic start and the automatic stop of the rotary tub, and the crusher itself does not have an automatic control function.
(5) For example, when a long member made of a wood
2
and the like is held-between the convex portion of the rotary tub
3
and the cutters
1
b
, a rotational force of the rotary tub
3
pushes the cutter via the wood
2
. Accordingly, an excess load is generated in the rotary crusher
1
, and the rotational speed is suddenly reduced. However, in the self-propelled crushing machine for crushing the wood
2
, there is an operational effect that the rotary tub
3
is further rotated, so that the nipped wood
2
is taken out and the crushing is again started. In the case that the predetermined value Na is set so as to automatically stop the rotary tub
3
, as in the prior art, this operational effect can not expected. On the contrary, when the thick and hard wood
2
is completely meshed with the cutters
1
b
, it is impossible to discharge the meshed wood
2
only by the automatic stop of the rotary tub
3
as in the prior art and it is necessary to discharge the wood
2
by human hands, so that the crushing efficiency is bad.
SUMMARY OF THE INVENTION
The present invention is made by taking the conventional problems mentioned above into consideration, and an object of the present invention is to provide a self-propelled crushing machine in which a crushed material having a widely desired grain size can be obtained, a degree of freedom for automatically controlling a rotary tub and a crusher can be preferably improved, and a crushing having a high efficiency can be performed.
In accordance with a first aspect of the present invention, there is provided a self-propelled crushing machine in which a rotary crusher and a rotary tub for introducing a material to be crushed thrown from an outer portion to the rotary crusher are provided on a self-propelled truck, and the material to be crushed which is introduced from the rotary tub is crushed by the rotary crusher and freely discharged to the outer portion, comprising target crushing rotational speed setting means for setting a target crushing rotational speed Nhm of the rotary crusher, actual crushing rotational speed detecting means for detecting an actual crushing rotational speed Nh of the rotary crusher, crusher drive means for setting the rotary crusher to be freely rotated, and control means for inputting a target crushing rotational speed Nhm from the target crushing rotational speed setting means, inputting the actual crushing rotational speed Nh from the actual crushing rotational speed detecting means and outputting a crushing rotation control signal Nhn for maintaining a relation Nh−Nhm=0 to the crusher drive means by comparing them.
In accordance with the first aspect, since the control means maintains the relation Nh−Nhm=0, it is possible to obtain a crushed material having a fixed grain size. Further, it is possible to freely set the target crushing rotational speed Nhm by the target crushing rotational speed setting means. Accordingly, it is possible to set an optimum target crushing rotational speed Nhm with respect to the materials to be crushed which are different in a hardness, a shape, a size and a batch, whereby the crushed material having a fixed grain size can be obtained. Further, it is possible to widely obtai

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