Abstrict The mechanical crusher includes a rotating shaft, a rotor mounted
about the rotating shaft and having at least one sub-rotor containing
a plurality of blades, a liner having a plurality of grooves formed
on the inner peripheral surface thereof and disposed externally
of the rotor with a predetermined gap defined between the inner
peripheral surface thereof and the outer-peripheral surface of the
rotor, and a drive unit for rotating the rotor. The blades of at
least the one sub-rotor incline in a direction where the flow of
a material to be crushed is forced back. With this arrangement,
the mechanical crusher can effectively crush a fiber-incluing material
such as wheat bran, and the like to fine powder.
Claims What is claimed is:
1. A mechanical crusher comprising: a rotating shaft; a rotor mounted
about said rotating shaft and having at least one sub-rotor containing
a plurality of blades; a liner having a plurality of grooves formed
on an inner peripheral surface thereof and disposed externally of
said rotor with a predetermined gap defined between the inner peripheral
surface thereof and an outer peripheral surface of said rotor; and
a drive unit for rotating said rotor and coupled to said rotating
shaft, wherein each of said plurality of blades of said at least
one sub-rotor inclines with respect to an axial direction of said
rotating shaft such that a flow of a material to be crushed is forced
back.
2. The mechanical crusher according to claim 1 wherein each of
said plurality of blades inclines at an angle of 10.degree. to 45.degree.
with respect to the axial direction of said rotating shaft.
3. The mechanical crusher according to claim 1 wherein disc-shaped
plate members each having a diameter smaller than an outermost diameter
of said at least one sub-rotor are disposed so as to clamp said
at least one sub-rotor in the axial direction of said rotating shaft.
4. The mechanical crusher according to claim 1 wherein said rotor
further comprises at least one sub-rotor having a plurality of blades
which are rectangular blades provided in a radial direction of said
rotor and in parallel to the axial direction of said rotating shaft.
5. The mechanical crusher according to claim 1 wherein a pitch
of said plurality of blades on said outer peripheral surface of
said rotor in a rotational direction of said rotor ranges 8 mm to
40 mm.
6. The mechanical crusher according to claim 5 wherein a size
of said plurality of blades in the rotational direction ranges 2
mm to 10 mm and a height of said plurality of blades in a radial
direction of said rotor ranges half of the pitch of said plurality
of blades to five times the pitch.
7. A mechanical crusher for a fibrous material comprising: a rotating
shaft; a rotor mounted about said rotating shaft and having at least
one sub-rotor containing a plurality of blades; a liner having a
plurality of grooves formed on an inner peripheral surface thereof
and disposed externally of said rotor with a predetermined gap defined
between the inner peripheral surface thereof and an outer peripheral
surface of said rotor; and a drive unit for rotating said rotor
and coupled to said rotating shaft, wherein a pitch of said plurality
of blades of at least one sub-rotor of said rotor on said outer
peripheral surface of said rotor in a rotational direction of said
rotor is set to 8 mm to 40 mm.
8. The mechanical crusher according to claim 7 wherein said rotor
further comprises disc-shaped plate members each having a diameter
smaller than an outermost diameter of said at least one sub-rotor
and disposed so as to clamp said at least one sub-rotor in an axial
direction of said rotating shaft.
9. The mechanical crusher according to claim 7 wherein said plurality
of blades are rectangular blades provided in a radial direction
of said rotor and in parallel to an axial direction of said rotating
shaft.
10. The mechanical crusher according to claim 7 wherein a size
of said plurality of blades in the rotational direction ranges 2
mm to 10 mm and a height of said plurality of blades in a radial
direction of said rotor ranges half of the pitch of said plurality
of blades to five times the pitch.
Description BACKGROUND OF THE INVENTION
The present invention relates to the technical field of a crusher
for crushing a fibrous material and a fiber-containing material
such as wheat bran, and the like, and more particularly, to a mechanical
crusher capable of finely crushing a fibrous material and a fiber-containing
material at a high efficiency.
Mechanical crushers such as the swirl type crusher disclosed in
Japanese Examined Utility Model Publication JU. 57-040104 B, the
turbo type crusher disclosed in Japanese Unexamined Patent Application
Publication JP. 51-064661 A, and the like have been used as an apparatus
for crushing a powder-like fiber-containing grain material such
as wheat bran to fine powder.
Various types of food that contains fibers are produced and distributed
as beauty foods and health foods. At that time, it is preferable
that the particle size of fiber-containing fine powder is such that
a maximum diameter is 100 .mu.m or less and an average diameter
is 30 .mu.m or less in order that these foods taste silky.
Further, in fiber-like powder for industrial use, for example,
carbon fiber and the like used in a fiber-reinforced composite material,
a material having a shorter fiber length is desired to improve mechanical
strength by uniformly blending the fiber-like powder with a binder.
In the conventional mechanical crushers as described above, however,
the number of revolution of a rotor must be increased to obtain
fiber-containing fine powder having the aforementioned particle
size with the maximum diameter of 100 .mu.m or less and the average
diameter of 30 .mu.m or less by crushing a fiber-containing material.
Thus, various problems arise in an efficiency of energy, a life
of the bearing of the rotor, occurrence of noise and vibration due
to the rotation of the rotor at a high speed, and so on.
Moreover, since there is a limit in an increase of the number of
revolution of the rotor, powder and/or grains obtained by crushing
a fiber-containing material by the conventional mechanical crushers
are often mixed with powder which is not crushed to a desired particle
size.
Accordingly, to obtain fiber-containing fine powder having a desired
particle size, it is necessary to execute a process for removing
coarse grains the particle size of which exceeds the desired particle
size by means of a classification device such as a sieve, an air
classifier, and the like, from which a problem is arisen in that
a production efficiency is bad.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve the
problems of the conventional art and to provide a mechanical crusher
for a fiber-containing material capable of effectively crushing
a fiber-containing material used for food such as wheat bran and
a fiber-like material for industrial use such as carbon fiber and
the like to fine powder having a maximum diameter of 100 .mu.m or
less and an average diameter of 30 .mu.m or less as a particle size.
To achieve the above object, the present invention provides a mechanical
crusher comprising a rotating shaft, a rotor mounted about the rotating
shaft and having at least one sub-rotor containing a plurality of
blades, a liner having a plurality of grooves formed on an inner
peripheral surface thereof and disposed externally of the rotor
with a predetermined gap defined between the inner peripheral surface
thereof and an outer peripheral surface of the rotor, and a drive
unit for rotating the rotor and coupled to the rotating shaft, wherein
each of the plurality of blades of the at least one sub-rotor incline
in a direction where flow of a material to be crushed is forced
back.
It is preferable that each of the plurality of blades inclines
at an angle of 10.degree. to 45.degree. with respect to an axial
direction of the rotating shaft.
It is also preferable that disc-shaped plate members each having
a diameter smaller than an outermost diameter of the at least one
sub-rotor are disposed so as to clamp the at least one sub-rotor
in an axial direction of the rotating shaft.
It is another preferable that the rotor further comprises at least
one sub-rotor having a plurality of blades which are rectangular
blades provided in a radial direction of the rotor and in parallel
to an axial direction of the rotating shaft.
It is further preferable that a pitch of the plurality of blades
on the outer peripheral surface of the rotor in a rotational direction
of the rotor ranges 8 mm to 40 mm.
It is still another preferable that a size of the plurality of
blades in the rotational direction ranges 2 mm to 10 mm and a height
of the plurality of blades in a radial direction of the rotor ranges
half of the pitch of the plurality of blades to five times the pitch.
To achieve the above object, the present invention provides a mechanical
crusher for a fibrous material comprising a rotating shaft, a rotor
mounted about the rotating shaft and having at least one sub-rotor
containing a plurality of blades, a liner having a plurality of
grooves formed on an inner peripheral surface thereof and disposed
externally of the rotor with a predetermined gap defined between
the inner peripheral surface thereof and an outer peripheral surface
of the rotor and a drive unit for rotating the rotor and coupled
to the rotating shaft, wherein a pitch of the plurality of blades
of at least one sub-rotor of the rotor on the outer peripheral surface
of the rotor in a rotational direction of the rotor is set to 8
mm to 40 mm.
It is preferable that the rotor further comprises disc-shaped plate
members each having a diameter smaller than an outermost diameter
of the at least one sub-rotor and disposed so as to clamp the at
least one sub-rotor in an axial direction of the rotating shaft.
It is another preferable that the plurality of blades are rectangular
blades provided in a radial direction of the rotor and in parallel
to an axial direction of the rotating shaft.
It is further preferable that a size of the plurality of blades
in the rotational direction ranges 2 mm to 10 mm and a height of
the plurality of blades in a radial direction of the rotor ranges
half of the pitch of the plurality of blades to five times the pitch.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a conceptual view showing an embodiment of a crushing
apparatus making use of a mechanical crusher of the present invention;
FIG. 2 is a schematic view partly in cross section showing an embodiment
of the mechanical crusher of the present invention;
FIG. 3 is a front elevational view of an embodiment of a rotor
of the mechanical crusher shown in FIG. 2;
FIG. 4 is a sectional view of the rotor of the mechanical crusher
taken along the line A--A of FIG. 3;
FIG. 5 is a view, partly in enlargement, of the rotor of the mechanical
crusher shown in FIG. 3;
FIGS. 6(A), (B) and (C) are conceptual views showing other embodiments
of the rotor used in the mechanical crusher of the present invention;
and
FIG. 7 is a schematic front elevational view showing another embodiment
of the rotor of the mechanical crusher shown in FIG. 2;
FIG. 8 is a graph showing a 50% particle size when wheat bran is
crushed in this example.
FIG. 9 is a graph showing the relationship between the pitch of
the blade and the cumulative 90% minus sieve particle size in the
example of the present invention; and
FIG. 10 is a graph showing the relationship between the pitch of
the blade and the power consumption rate in the example of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
A mechanical crusher of the present invention used to crush a fiber-containing
material will be described in detail with reference to a preferred
embodiment shown in the accompanying drawings.
The mechanical crusher of the present invention crushes a fiber-containing
material used for food such as wheat bran, and the like and a fiber-like
material for industrial use such as carbon fiber, and the like to
fine powder.
A fiber-containing material handled by the mechanical crusher of
the present invention is not particularly limited, and the mechanical
crusher of the invention can crush various types of fiber-containing
materials, for example, a fiber-containing material used for food
that contains a large amount of dietary fiber that is defined as
"the whole difficult-to-digest components contained in food
which cannot be broken down by human digestive enzymen", a
fiber-like material for industrial use such as various types of
inorganic and organic, and so on.
Preferably exemplified as specific examples which are handled by
the mechanical crusher of the present invention are fiber-containing
materials used for food, for example, wheat bran, been-curd refuse,
powdered green tea, dry "wakame", that is, a kind of seaweed
(Undaria species), dry "hijiki", that is, a kind of brown
algae (Hizikia species), dry layer, dry vegetable, and the like
and fiber-like materials for industrial use, for example, various
types of fiber such as carbon fiber, acrylic fiber, aramid fiber,
nylon fiber, silk, and the like, sawdust (wood powder and chips),
pulp, and so on.
It is preferable that the size of these fiber-containing or fiber-like
materials used for as the crude materials be 20 mm or less and the
water content thereof be 10 wt % or less.
FIG. 1 shows an embodiment of a crushing apparatus for crushing
a fiber-containing material making use of a mechanical crusher (hereinafter,
simply referred to as "crusher") 10 of the present invention.
The illustrated crushing apparatus 50 includes the crusher 10 of
the present invention, a screw feeder 12 a bag filter 14 and a
blower 16.
The fiber-containing material to be crushed as the crude material
is supplied to the material introduction port 18 of the crusher
10 of the present invention by the screw feeder 12.
Further, the blower 16 is coupled with the discharge port 20 of
the crusher 10 through the bug filter 14 so that the interior of
the crusher 10 (crusher main body 22) is sucked by the blower 16.
Accordingly, the fiber-containing material supplied to the introduction
port 18 by the screw feeder 12 is crushed to fine powder while being
transported to the upper portion of the crusher 10 from the introduction
port 18 to the discharge port 20 by the air stream formed by the
sucking operation of the blower 16 and discharged from the discharge
port 20.
The thus discharged fiber-containing fine powder is further transported
by the air stream formed by the blower 16 and taken out after it
is captured by the bug filter 14.
FIG. 2 is a schematic view partially in cross section showing an
embodiment of the crusher 10 of the present invention.
The crusher 10 of the present invention is composed of the crusher
main body 22 and a rotation device 24.
The rotation device 24 includes a motor 26 a pulley 28 fixed to
the shaft 26a of the motor 26 a pulley 30 fixed to the lower end
of a rotating shaft 38 which will be described later, and an endless
transmission belt 32 trained around the pulleys 28 and 30 with tension.
The rotation of the motor 26 rotates the rotating shaft 38 therefore,
a rotor 40 (rotor assembly of the rotor 40 composed of four sub-rotors
41) which will be described later at a predetermined number of revolution.
That is to say, the rotation device 24 functions a drive unit for
rotating the rotor 40.
In contrast, the crusher main body 22 is composed of a casing 34
having the introduction port 18 and the discharge port 20 which
were described above, a liner 36 disposed on the inner surface of
the casing 34 the rotating shaft 38 and the rotor 40 mounted about
and fixed to the rotating shaft 38. The rotor 40 may be produced
integrally with the rotating shaft 38 or the rotor 40 and the rotating
shaft 38 may be produced separately and combined with and fixed
to each other.
When necessary, the crusher main body 22 may be cooled by cooling
the casing 34 and the like with water.
The liner 36 is formed in a cylindrical shape, has a multiplicity
of grooves 36a formed on the inner surface thereof, and is disposed
in the inside of the casing 34 so as to accommodate the rotor 40
with a predetermined gap defined between the inner peripheral surface
(the extreme ends of ribs where the grooves 36a are formed) thereof
and the outer peripheral surface (the extreme ends of blades 44
to be described later) of the rotor 40. In the invention, the liner
36 may also be a known liner used in various types of mechanical
crusher that uses a rotor and a liner.
The shape, pitch, and the like of the grooves 36a of the liner
36 are not particularly limited, and a known liner may be selected
and used according to the quality of the fiber-containing material,
the target particle size of fine powder, and the like. Exemplified
as the liner is, for example, a liner including triangular grooves,
which have a depth of 4 mm and are formed at a pitch of 6 mm along
the rotating direction (the peripheral direction of the inner peripheral
surface of the liner) of the rotor 40 and extending in the same
direction as the rotating shaft 38 (hereinafter, referred to as
an "axial direction").
Further, the gap defined between the inner peripheral surface of
the liner 36 and the outer peripheral surface of the rotor 40 is
not particularly limited. However, it is preferable to set the gap
to about 1 mm to 10 mm because the gap of this size permits a fiber-containing
material to be preferably crushed, and permits fine powder having
a maximum diameter of 100 .mu.m or less and an average diameter
of 30 .mu.m or less to be effectively obtained from a fiber-containing
material used for food. It is preferable that this gap be uniformly
formed between the inner peripheral surface of the liner 36 and
the outer peripheral surface of the rotor 40.
The rotating shaft 38 is rotatably journaled between bearings 34a
and 34a disposed on the upper and lower ends of the casing 34. As
described above, the pulley 30 of the rotation device 24 is fixed
to the lower end of the rotating shaft 38 that is rotated by driving
the motor 26. Thus, the rotor 40 fixed to the rotating shaft 38
is rotated when the rotating shaft 38 is rotated through the transmission
belt 32 by driving the motor 26.
FIG. 3 shows a schematic front elevational view of the rotor 40
of the crusher 10 of the first aspect of the present invention,
and FIG. 4 shows a schematic sectional view of the rotor 40 taken
along the line A--A of FIG. 3 respectively.
The rotor 40 of the crusher 10 is mainly related to the crushing
of a fiber-containing material to be crushed.
As shown in FIGS. 3 and 4 the rotor 40 is formed in a cylindrical
shape with the center thereof in coincidence with the center of
rotation of the rotating shaft 38 and includes a central section
42 fixed to the rotating shaft 38 and the blades 44 that are formed
in a rectangular plate shape and project from the outer peripheral
surface of the central section 42 in radial directions. These blades
44 are provided in a predetermined number (16 pieces in the exemplified
example) at predetermined intervals in a rotational direction (peripheral
direction of the central section 42). Note that, in FIG. 3 the
extreme end surfaces of the blades 44 are shown with recticulations
to make the arrangement thereof distinct.
The rotor 40 also may be arranged by integrally producing the blades
44 and the central section 42 or the rotor 40 may be arranged by
separately producing the blades 44 and the central section 42 and
combining and fixing them with and to each other.
Note that, in the crusher 10 of the present invention, the sectional
shape of the blades 44 is not limited to the rectangular plate shape
of the illustrated embodiment shown in FIG. 4 and various types
of shape such as a triangular shape, and the like used in known
mechanical crushers can be utilized. However, in the present invention,
since the fiber-containing material is basically crushed by being
impacted and struck with the blades 44 of the rotor 40 it is preferable
to form the cross section of the blades 44 in the rectangular plate
shape as shown in the illustrated embodiment.
As a preferable aspect of the illustrated crusher 10 a single
rotor (the rotor assembly) 40 is arranged by stacking sub-rotors
41a, 41b, 41c and 41d in four stages in the axial direction and
disposing disc-shaped partitions 46 so as to clamp the sub-rotors
41a to 41d, which constitute the entire rotor 40 in the axial direction.
Note that the partitions 46 may be produced integrally with the
sub-rotors 41a to 41d of the rotor 40 or the partitions 46 and
the sub-rotor 40a to 40d of the rotor 40 may be separately produced
and combined and fixed with and to each other.
Note the rotor may be composed of one sub-rotor or a plurality
of sub-rotors. Therefore, in case of the rotor having one sub-rotor,
the rotor may be arranged by providing one sub-rotor at the center
portion of the rotating shaft in the axial direction and dispusing
two disc-shaped partitions at both sides of the subu-rotor in the
axial direction. In case of the rotor having a plurality of sub-rotors,
the rotor may be arranged by stacking a plurality of sub-rotors
and disposing each of the disk-shaped partitions between the adjacent
sub-rotors and out sides of both outermost sub-rotors in the axial
direction.
In the illustrated embodiment, the uppermost stage sub-rotor 41a
has the characteristic arrangement of the present invention. That
is, the blades 44 of the uppermost stage sub-rotor 41a incline in
a direction where the flow of a material to be crushed is forced
back, while the blades 44 of the other sub-rotors 41b to 41c are
disposed so as to extend in the axial direction.
In the crusher 10 of the present invention, at least one of the
sub-rotors 41a to 41d has the inclining blades 44 which permits
the fiber-containing material such as wheat bran and the fiber-like
material such as carbon fiber, and the like to be effectively crushed
to fine powder.
FIG. 5 schematically shows the action of the blades 44 that incline
in the direction where the material to be crushed is forced back.
Note that, in the present invention, the expression that "the
blades of the rotor (sub-rotor) incline in the direction where the
material to be crushed is forced back" means that the blades
44 of the rotor 40 (sub-rotor 41) in rotation (in the direction
of an arrow x) generate an air stream in a direction opposite to
the direction where the material to be crushed (fiber-containing
material) w which is supplied into the crusher 10 is transported
therein (the direction of an arrow y in the figure)
As shown in FIG. 5 the material to be crushed w is transported
in the direction of the arrow y by the air stream generated by the
blower 16 collides against the blades 44 of the rotor 40 in rotation,
and is crushed thereby.
Grains having a large size are liable to fall into the space (pocket)
between the adjacent blades 44 and to collide against the blades
44 because they are unlike to be flown by the air stream In addition
to the above-mentioned, after these grains collide against the blades
44 they are forced back upward (direction opposite to the direction
where they are transported by the air stream) by the action of the
inclining blades 44 as shown by an arrow z. That is, fine grains
that have been crushed sufficiently are transported downstream by
the air stream generated by the blower 16 and discharged from the
crusher 10. In contrast, grains having a large size are forced back
by the inclining blades 44 repeat collision against the blades
44 and are subjected to a crushing operation many times until they
are sufficiently crushed.
The crusher 10 of the present invention permits the fiber-containing
material and the fiber-like material, which cannot be finely crushed
by the conventional crusher apparatus effectively, to be crushed
to fine powder effectively.
In the crusher 10 of the present invention, the inclining angle
of the blades 44 (angle .theta. shown in FIG. 5) is not particularly
limited and the blades 44 may incline at any angle in the above
direction in which the material to be crushed is forced back, that
is, the inclining angle .theta. may be set to any angle exceeding
0.degree. and less than 90.degree.. In particular, it is preferable
to set the inclining angle to 10.degree. to 45.degree. because fine
crushing can be effectively executed at any angle set within the
range of these angles.
As described above, in the illustrated crusher 10 the single rotor
is constructed by stacking the sub-rotors 41a to 41d of the four
stages in the axial direction through the disc-shaped partitions
46 and the blades 44 of only the uppermost stage sub-rotor 41a
incline.
In the sub-rotor 41b of a second stage (hereinafter, the number
of stages is counted from the upper side) to the lowermost stage
sub-rotor 41d, adjacent sub-rotors are disposed such that the positions
of the blades 44 thereof are offset in a rotating direction (direction
of an arrow x in FIGS. 3 and 4) each other. That is, in FIG. 3
a third stage sub-rotor shows a state in which the rotor 40 is viewed
in the direction of an arrow a in FIG. 4 and a second stage sub-rotor
and a lowermost stage sub-rotor show a state in which the rotor
40 is viewed from the direction of an arrow b in FIG. 4.
As described above, the rotor 40 is composed of at least two stages
of the sub-rotors and further the positions of the blades 44 are
offset in the rotating direction in stages of the rotors adjacent
to each other in the axial direction, whereby the fiber-containing
material and the fiber-like material can be crushed more preferably.
Note that when the crusher 10 is constructed by the rotor 40 including
a plurality of stages, the number of the stages is not particularly
limited.
Further, when the rotor 40 has a plurality of stages of sub-rotors
as shown in the illustrated embodiment, the respective sub-rotors
41a to 41d (and the partitions 46) may be produced integrally, or
the sub-rotors and the partitions may be produced separately and
combined with and fixed to each other.
As described above later, however, it is possible in the crusher
of the present invention to combine various types of sub-rotors.
Accordingly, it is preferable to combine sub-rotors produced separately
and to combine and fix them with and to each other to cope with
a variation of the combinations thereof.
As a preferable aspect of the illustrated crusher 10 the partitions
46 are disposed so as to clamp the respective sub-rotors 41a to
41d in the axial direction. While the partitions 46 are not essential
in the present invention, the provision of them can more improve
the crushing efficiency of the fiber-containing material and the
fiber-like material.
Note that the size of the partitions 46 is not particularly limited.
According to the examination of the inventors, however, it is preferable
that the size of the partitions 46 be slightly smaller than the
outermost diameter (the extreme end of the blades 44) of the rotor
40. In particular, it is preferable that the size of the partitions
46 he smaller than the outermost diameter of the rotor 40 by 2 mm
to 40 mm in radius.
The illustrated crusher 10 has the rotor 40 composed of the sub-rotors
41a to 41d of the four stages, and the blades 44 of only the uppermost
stage sub-rotor 41a incline in the direction where the flow of the
material to be crushed is forced back (hereinafter, simply referred
to as "incline") However, the combination of the sub-rotors
in the crusher of the present invention is not limited thereto and
various combinations are possible as described above.
For example, as schematically shown in FIG. 6A, sub-rotors 41a
and 41b having blades 44 that incline similarly may be used in uppermost
and second stages, respectively, a sub-rotor 41c having blades 44
that incline at a small angle may be used in a third stage, and
a sub-rotor 41d having blades 44 without inclination may be used
in a lowermost stage.
Otherwise, as shown in FIG. 6B, a sub-rotor 41a having blades 44
that incline at a large angle may be used in an uppermost stage,
a sub-rotor 41c having blades 44 that incline at a small angle may
be used in a third stage, and sub-rotors 41b and 41d having blades
44 without inclination may be used in second and lowermost stages
respectively.
Further, as shown in FIG. 6C, sub-rotors 41b and 41d having blades
44 that incline in a direction opposite to the direction where the
flow of the material to be crushed is forced back may be combined
with sub-rotors 41a and 41c having blades 44 that incline in the
direction where the flow of the material to be crushed is forced
back.
In the present invention, sub-rotors 41a to 41d having blades 44
that incline similarly may be used in all the stages, sub-rotors
41a to 41d having blades 44 that incline at a different angle may
be used in all the stages, and a sub-rotor 41d having inclining
blades 44 may be used only in the lowermost stages in addition to
the above arrangements. That is, the present invention can use various
combinations of sub-rotors 41.
Further, while all of the above examples have the four-stage sub-rotors,
the present invention is by no means limited thereto as described
above.
In the sub-rotors 41 of the crusher 10 of the present invention,
the pitch P of the blades 44 on the outer peripheral surface thereof,
the thickness c of the blades 44 and the height h of the blades
44 (length of the central section 42 in a radial direction) are
not particularly limited and may be suitably determined according
to the scale and the like of the crusher 10 regardless of whether
the blades 44 of the sub-rotors incline or not.
According to the examination of the inventors, as descirbed above,
it is preferable that the pitch P of the blades 44 be set to 8 mm
to 40 mm, that the thickness c of the blades 44 be set to 2 mm to
10 mm, and that the height h of the blades 44 be set to half of
the pitch P of the blades 44 to five times the pitch 2 more preferably
one to five times the pitch P of the blades 44 respectively.
Satisfying at least one or all of the above conditions permits
the fiber-containing material and the fiber-like material to be
crushed more preferably and more excellent fine powder of fiber
to be obtained.
A method of producing the sub-rotors 41 and the rotor 40 is not
particularly limited and any known method such as cutting and the
like can be used. Further, after the rotor 40 is produced, the hardness
of the surface thereof may be improved by a method such as induction
hardening, thermal spraying, CVD coating, or the like.
Further, a material for forming the rotor 40 is not particularly
limited, and a steel material such as SS, S45C, etc., for example,
may be used.
In the crusher 10 of the present invention having the rotor 40
arranged as described above, the rotational speed of the rotor 40
is not particularly limited.
However, it is preferable to set such a rotational speed that the
peripheral speed of the rotor 40 is set to 60 m/sec to 160 m/sec,
in particular 80 m/sec to 140 m/sec on the outer peripheral surface
thereof in order to execute crushing excellently.
Furthermore, in the rotor 40 of the crusher 10 of the present invention,
as shown in FIG. 7 a plurality of blades 44 of the sub-rotors 41
in all the stages may be blades in the rectangular plate shape which
have no inclination, that is to say, which extend from the center
section 42 of the rotor 40 in radial directions and are positioned
longitudinally in parallel with the axial direction of the rotating
shaft 38. It should be noted that FIG. 4 may be also accounted a
sectional view of the second stage sub-rotor 41 of the rotor 40
shown in FIG. 7.
Also in the rotor 40 shown in FIG. 7 adjacent sub-rotors 41 are
disposed such that the positions of the blades 44 thereof are offset
in a rotating direction (direction of an arrow x in FIGS. 7 and
4) each other, as is the case with the rotor 40 shown in FIG. 3.
That is, in FIG. 7 an uppermost stage and a third stage show a
state in which the sub-rotors 41 are viewed in the direction of
an arrow a in FIG. 4 and a second stage and a lowermost stage in
FIG. 7 show a state in which the sub-rotors 41 are viewed from the
direction of an arrow b in FIG. 4. In this case also, the rotor
40 is composed of at least two stages of the sub-rotors 41 and the
positions of the blades 44 are offset in the rotating direction
in stages adjacent to each other in the axial direction, whereby
the fiber material such as the fiber-containing material and the
fiber-like material can be crushed more preferably.
When the rotor 40 shown in FIG. 7 is used, it is required that
the blades 44 of each of sub-rotors 41 as stated above be arranged
such that the pitch P shown in FIG. 4 which is the pitch of the
blades 44 in the rotating direction on the outer peripheral surface
of the sub-rotor 41 (pitch of the extreme ends of the blades 44),
is 8 mm to 40 mm, preferably 10 mm to 30 mm.
As mentioned before, when a fiber material such as a fiber-containing
material and a fiber-like material is to be crushed to fine powder
having a particle size of 100 .mu.m or less by any conventional
mechanical crusher, it is necessary, for example, to increase the
number of revolution of the rotor 40 and a problem of low efficiency
occurs because crushing can not be effected desirably with such
crushers.
In contrast, according to the present invention, it is possible
to crush a fiber material such as wheat bran to fine powder having
a particle size of 100 .mu.m or less by setting the pitch P of the
blades 44 on the outer peripheral surface of the rotor (hereinafter
referred to as "blade pitch P") to 8 mm to 40 mm. The
fine powder thus obtained can be suitably added to various foods.
As will be evident from the Example 7 stated below, if the blade
pitch P is larger than 40 mm, the efficiency in crushing of a fiber
material is decreased and fine powder of fiber crushed to a particle
size of 100 .mu.m or less can not be obtained at a high efficiency.
On the other hand, the crushing efficiency is again decreased with
the blade pitch P which is too small. If the blade pitch P is smaller
than 8 mm, fine powder of fiber crushed to a particle size of 100
.mu.m or less can also not be obtained at a high efficiency.
Also in the rotor 40 shown in FIG. 7 the thickness c (the size
in the rotating direction) of the blades 44 is not particularly
limited and is preferably 2 mm to 10 mm.
The height h (the length in a radial direction of the center section
42) of the blades 44 of this rotor 40 is also not particularly limited.
It is preferably half of the blade pitch P to five times the blade
pitch P, more preferably one to five times the blade pitch P.
Satisfying one, or both espetially, of above two conditions permits
the fiber-containing material and the fiber-like material to be
crushed more preferably and more excellent fine powder of fiber
to be obtained.
In the examples as described above, the rotating shaft 38 is arranged
vertically, although the present invention is not limited to such
an arrangement. The rotating shaft 38 may also be arranged horizontally,
for example.
While the mechanical crusher of the present invention has been
described above in detail, the present invention is by no means
limited to the aforementioned embodiments and it goes without saying
that various improvements and modifications can be made within the
range which does not depart from the gist of the present invention.
EXAMPLES
The present invention will be described in more detail by exemplifying
specific examples of crushing carried out by the mechanical crushers
of the present invention. It is needless to say that the present
invention is not limited thereto.
Example 1
A crusher 10 of the first aspect of the present invention was produced
which was arranged such that a rotor 40 shown in FIG. 3 had a diameter
(extreme end of blades 44) of 150 mm, the gap between the rotor
40 and a liner 36 was set to 2 mm, the height h of the blades 44
was set to 20 mm, the thickness c of the blades 44 was set to 6
mm, the number of the blades 44 was set to 16 pieces, the height
of a single sub-rotor 41 was set to 45 mm, the number of stages
of the sub-rotors 41 of the rotor 40 was set to four states, the
diameter of partitions 46 was set to 136 mm, and the thickness of
the partitions 46 was set to 5 mm. The crusher apparatus 50 shown
in FIG. 1 was constructed using the crusher 10 and wheat bran having
a particle size of about 2 mm was crushed thereby.
Wheat bran was supplied through a screw feeder 12 in an amount
of 1 kg/hr. Further, the number of revolution of the rotor 40 was
set to 10000 rpm to 14000 rpm, and the volume of air supplied
from a blower 16 was set to 2 m.sup.3 /min.
Under the above conditions, wheat bran was crushed by replacing
the uppermost stage sub-rotor 41a of the crusher 10 with three types
of sub-rotors 41 the inclining angle .theta. of the blades 44 of
which was set to 0.degree., 15.degree., and 30.degree., respectively.
Note that the inclining angle of the blades 44 of the sub-rotors
41b, 41c and 41d of the stages other than the uppermost stage was
set to 0.degree..
The 50% particle size of the wheat bran having been crushed was
measured with a dry type laser particle size measuring instrument
(Microtrack), and FIG. 8 is a graph showing the result of measurement.
In FIG. 8 a symbol .largecircle. indicates the result of measurement
when the sub-rotor 41a the blades 44 of which had the inclining
angle .theta. set to 0.degree. was used, a symbol .tangle-solidup.
indicates the result of measurement when the sub-rotor 41a the blades
44 of which had the inclining angle .theta. set to 15.degree. was
used, and a symbol X indicates the result of measurement when the
sub-rotor 41a the blades 44 of which had the inclining angle .theta.
set to 30.degree. was used, respectively. As apparent from the graph,
the crusher of the present invention could crash wheat bran more
finely as compared with the case in which wheat bran was crushed
with the crusher of the second aspect of the present invention as
the reference example when the wheat bran was crushed under the
same conditions, and further the number of revolution of the rotor
of the crusher of the first aspect of the present invention could
be greatly reduced when the same particle size was obtained in crushing,
whereby the crushing capability of the crusher of the first aspect
of the present invention could be greatly improved.
Example 2
A crusher 10 was constructed similarly to the Example 1 except
that the inclining angle .theta. of the blades 44 of uppermost stage
and second stage sub-rotors 41a and 41b was set to 30.degree. and
that the inclining angle .theta. of the blades 44 of a third stage
sub-rotor 40c was set to 15.degree. as shown in FIG. 6A. Wheat bran
was crushed using the crusher 10 similarly to the Example 1 except
that the number of revolution of a rotor 40 was fixed to 14000
rpm.
When the 50% particle size of the wheat bran having been crushed
was measured similarly to the Example 1 it was 9.5 .mu.m, whereby
it was confirmed that the wheat bran could be crushed greatly finely
as compared with the case in which wheat bran was crushed with the
crusher as the Example 1 and the reference example.
Example 3
A crusher 10 was constructed similarly to the Example 1 except
that the pitch P of the blades 44 of second stage to lowermost stage
sub-rotors 41b to 41d was set to one half that the blades 44 of
the Example 1 and that the number of the blades 44 was set to 32
pieces. Wheat bran was crushed using the crusher 10 similarly to
the Example 1 except that the number of revolution of a rotor 40
was fixed to 10000 rpm.
When the 50% particle size of the wheat bran having been crushed
was measured similarly to the Example 1 it was 26 .mu.m, whereby
it was confirmed that the wheat bran could be crushed greatly finely
as compared with the case in which wheat bran was crushed with the
crusher as the reference example.
Example 4
A crusher 10 was constructed similarly to the Example 1 except
that the inclining angle .theta. of the blades 44 of an uppermost
stage sub-rotor 41a was set to 30.degree. and the inclining angle
.theta. of the blades 44 of a third stage sub-rotor 41c was set
to 15.degree. as shown in FIG. 6B. Wheat bran was crushed using
the crusher 10 similarly to the Example 1 except that the number
of revolution of a rotor 40 was fixed to 14000 rpm.
When the 50% particle size of the wheat bran having been crushed
was measured similarly to the Example 1 it was 17.6 .mu.m, whereby
it was confirmed that the wheat bran could be crushed greatly finely
as compared with the case in which wheat bran was crushed with the
crusher as the reference example.
Example 5
A crusher 10 was constructed similarly to the Example 1 except
that the inclining angle .theta. of the blades 44 of an uppermost
stage sub-rotor 41a was set to 30.degree., the inclining angle .theta.
of the blades 44 of a second stage sub-rotor 41b was set to -30.degree.,
the inclining angle .theta. of the blades 44 of a third stage sub-rotor
41c was set to 30.degree., and the inclining angle .theta. of the
blades 44 of a lowermost stage sub-rotor 41d was set to -30.degree.
as shown in FIG. 6C. Wheat bran was crushed using the crusher 10
similarly to the Example 1 except that the number of revolution
of a rotor 40 was fixed to 14000 rpm.
When the 50% particle size of the wheat bran having been crushed
was measured similarly to the Example 1 it was 21.6 .mu.m, whereby
it was confirmed that the wheat bran could be crushed greatly finely
as compared with the case in which wheat bran was crushed with the
crusher as the reference example.
Example 6
Polyamide resin having a fiber length of about 0.2 mm was crushed
with a crusher apparatus 50 similarly to the Example 3 (that is,
using the same crusher 10 as the Example 3). The polyamide was supplied
through a screw feeder 12 in an amount of 0.3 kg/hr, the number
of revolution of a rotor 40 was set to 14000 rpm, and the amount
of air supplied from a blower 16 was set to 2 m.sup.3 /min.
When the 50% particle size of a resulting crushed product was measured
with a wet type laser particle size measuring instrument (Microtrack),
it was 24 .mu.m. When polyamide resin was crushed using the crusher
of the reference example of in the Example 1 under the same conditions,
the 50% particle size of a resulting crushed product was 48 .mu.m,
whereby it was confirmed that the polyamide resin could be crushed
greatly finely as compared with the case in which polyamide resin
was crushed with the crusher as the reference example.
Example 7
In the crusher apparatus 50 shown in FIG. 1 wheat bran was crushed
varying the blade pitch P of respective sub-rotors 41 of the rotor
40 in the crusher main body 22 as shown in FIG. 7.
In the rotor 40 (sub-rotors 41) used, the rotor diameter (the maximum
diameter as measured to the extreme ends of blades 44) was 150 mm,
as well as the height h of the blades 44 was 40 mm, their thickness
c was 6 mm and their size in the axial direction was 50 mm. In the
case of the rotor with the blade pitch P of about 6 mm, the thickness
c of the blades 44 was changed into 4 mm and their height h into
8 mm for reasons of production and arrangement. In the crusher main
body 22 four stages of sub-rotors 41 were stacked to a single rotor
40 as shown in FIG. 7.
As the liner 36 was used a liner including triangular grooves 36a
of a 4 mm depth extending in the axial direction, which were formed
in the inner peripheral surface of the liner 36 at a pitch of 6
mm along the rotating direction.
Using the crusher apparatus 50 comprising such components as above,
wheat bran having a particle size of about 2 mm, which was supplied
through the screw feeder 12 at a rate of 5 kg/hr, was crushed under
suction by the blower 16 at an air flow rate of 1.5 m.sup.3 /min.
FIG. 9 shows the relationship between the blade pitch P and the
cumulative 90% minus sieve particle size (the particle size in which
the cumulative size distribution (the under size distribution) is
90%) when the number of revolution of the rotor 40 was set to 14000
rpm (corresponding to an air velocity of 109.9 m/sec).
As seen from FIG. 9 according to the present crusher 10 wherein
the blade pitch P is 8 mm to 40 mm, it is possible to crush wheat
bran suitably to obtain fine powder having a particle size of 100
.mu.m or less at a high efficiency.
Further, FIG. 10 shows the relationship between the blade pitch
P and the power required for crushing a material of a unit weight
(power consumption rate) when the number of revolution of the rotor
40 was adjusted such that the crushed product had the cumulative
50% minus sieve particle size of 20 .mu.m.
As seen from FIG. 10 according to the present crusher 10 wherein
the blade pitch P is 8 mm to 40 mm, it is possible to finely crush
wheat bran with an energy efficiency higher than ever.
The advantage of the present invention will be apparent from the
above results.
As described above in detail, according to the mechanical crusher
of the present invention, fiber materials including a fiber-containing
material used for food such as wheat bran and the like and a fiber-like
material for industrial use such as carbon fiber and the like can
be more finely crushed at a high efficiency, making it possible
to obtain fine powder of fiber having a particle size of 100 .mu.m
or less at a high efficiency, for example.
Consequently, if the present invention is applied to foods, for
example, those health foods and beauty foods can be desirably produced
which contain fine powder of fiber and yet have pleasant feels in
the mouth, as testing silky or being smooth on the tongue, for example. |