Abstrict A moving point involved in a movable teeth plate of an eccentric
jaw crusher rotates on a closed loop, being called hysteresis curve
in the specification. The motion of rotation has a top side dead
point and a bottom side dead point on one cycle. The normal rotation
in the normal direction enables harder materials, concrete, for
example to be crushed at high efficiency, the reverse rotation in
the reverse direction enabling soft materials, asphalt, for example
to be also crushed at high efficiency. One self moving crusher can
crush harder and soft materials at the same field where buildings
are destroyed, or roads are repaired.
Claims What is claimed is:
1. A method for operating an eccentric jaw crusher having a fixed
crushing plate and a movable crushing plate in which a selected
point on said movable crushing plate moves with respect to said
fixed crushing plate, comprising the steps of:
moving said movable crushing plate with respect to said fixed crushing
plate along a path defined by a closed hysteresis curve having a
top dead point and a bottom dead point and which is inclined with
respect to a facing surface of said fixed crushing plate, and
selectively moving said movable plate to traverse said hysteresis
curve in a first direction for crushing a first material or in a
reverse direction for crushing a second material.
2. A method for operating an eccentric jaw crusher of claim 1
in which said movements of said movable crushing plate include
movement in a normal direction, wherein said selected point on
said movable crushing plate moves towards said fixed crushing plate
at the top dead point of said hysteresis curve for crushing said
first material, and
movement in a reverse direction, wherein said selected point on
said movable crushing plate moves towards said fixed crushing plate
at said bottom dead point of said hysteresis second material.
3. A method for operating a jaw crusher of claim 1 including the
steps of:
moving said selected point upwards towards said top dead point
on an upper portion of said closed hysteresis curve for crushing
said first material, and moving said selected point upwards towards
said top dead point on a lower portion of said closed hysteresis
curve for crushing said second material.
4. A method for operating a jaw crusher of claim 1 including the
steps of:
moving said selected point upwards on said upper portion of said
hysteresis curve towards said top dead point during crushing of
hard material, moving said selected point upwards on said lower
portion of said hysteresis curve towards said top dead point during
crushing of softer material.
5. A method for operating an eccentric jaw crusher of claim 1
including the steps of:
varying the inclination of said closed hysteresis curved line.
6. A method for operating a jaw crusher including a machine body
mounting a fixed crushing plate and a movable crushing plate supported
by supporting means to be eccentrically driven with respect to said
fixed crushing plate whereby a selected point on said movable crushing
plate moves along a path defining a closed hysteresis path formed
by an upper curve portion and a lower curve portion, the opposite
ends of which are closed by an upper dead point and a lower dead
point, respectively, and a flywheel giving force to said movable
crushing plate, said method comprising the steps of:
moving said movable crushing plate in a normal direction wherein
said selected point moves along said upper portion of said hysteresis
path and nearer to said fixed crushing plate at said top dead point
for crushing hard material, and
moving said movable crushing plate in a reverse direction wherein
said selected point moves away from said fixed crushing plate at
said top dead point along a lower portion of said hysteresis path
and for crushing softer material.
7. A method for operating an eccentric jaw crusher of claim 6
wherein said closed hysteresis curve includes an upper portion and
a lower portion, and including the steps of:
moving said selected point on said movable crushing plate upwards
on said upper portion of said hysteresis curve towards said upper
dead point during crushing of said hard material, and moving said
selected point on said movable crushing plate upwards on said lower
portion of said hysteresis curve towards said upper dead point during
crushing of said softer material.
8. A method for operating an eccentric jaw crusher of claim 7 having
a hydraulic valve for changing the direction of movement of said
movable plate comprising the steps of:
changing the direction of movement of said movable plate from a
normal direction to a reverse direction by operating said hydraulic
valve.
9. A method for operating an eccentric jaw crusher,
having a fixed crushing plate and a movable crushing plate, wherein
a selected moving point on said movable crushing plate moves on
a closed hysteresis curved line having a top side dead point and
a bottom side dead point, comprising the steps of:
reversing the directions in which said selected moving point moves,
and
varying said closed hysteresis curved line in response to the hardness
of the material to be crushed.
Description FIELD OF THE INVENTION
The present invention relates to a method for operating a jaw crusher
and particularly relates to a method for operating a jaw crusher
which is operated in a multiple of modes in correspondence to kinds
of materials.
BACKGROUND OF THE INVENTION
An eccentric jaw crusher was invented more than one hundred years
ago. A V-shaped crushing space is formed between two crushing plates,
namely, a fixed plate and a movable plate. The movable plate swings
around an eccentric shaft. The crushing space is formed narrower
in the lower portion than in the upper portion. Materials are thrown
down into the upper portion. A thrown-down material, for example,
a piece of stone, is pressed at three points in theory. A selected
moving point disposed on the moving plate moves in a closed loop.
The closed loop has an upper portion and a lower portion divided
by a major axis. The upper portion and a lower portion are not generally
symmetric with respect to the major axis. In this specification,
a closed loop is called a hysteresis curved line or hysteresis curve.
Both crushing plates press a stone. The differential interval between
both crushing plates during crushing the stone is very short. Thereby,
a great quantity of energy, which the moving crushing plate has,
is instantly transmitted to the stone. Such great energy concentrates
locally in the weak portion or inner surface of the stone. Such
local concentration allows the stone to be instantly crushed.
An eccentric jaw crusher having such ability of crushing has been
applied for crushing hard stones but are recently tried to be utilized
for crushing softer materials, for example, asphalt. Self-moving
eccentric jaw crushers have been developed by the present inventor.
A self moving eccentric jaw crusher is developed for crushing materials
which are destroyed at places where buildings are being destroyed
or on roads which are being repaired. Such crushed pieces of materials
are recycled at the same place as the original materials are crushed.
It is desirable that one eccentric jaw crusher is utilized or operated
both for crushing hard materials, concrete for example, and for
crushing softer material, asphalt for example. It has been considered
that a jaw crusher is not suitable for crushing softer materials,
because it has been designed for crushing hard materials.
In fact, softer materials like asphalt are not crushed into a plurality
of pieces but, instead, are pressed and destroyed by plastic deformation,
especially in summer seasons. As a result, the plasticly deformed
material becomes adhesively connected to one plate, thereby it making
motion of the other plate impossible. Such occurrence necessitates
stopping of the machine and a requirement to rotate the motor in
the reverse direction of rotation so as to remove the material adhesively
connected to the surface of the crushing plate. After removing the
adhesive material, the crushing plate is again rotated in the forward
direction.
The present inventor found that reverse rotation of the plate makes
it possible to crush effectively softer material. The inventor,
who has recognized that the lower portion of the moving crushing
plate does not move on a straight line but on a curved line having
a hysteresis, though it looks like a straight line, found that such
phenomena are theoretically described. Such motion having a hysteresis
is mathematically described in U.S. Pat. No. 5397069.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for operating
an eccentric jaw crusher, wherein both hard and softer materials
are crushed at the respective high efficiencies of crushing.
A further object of the present invention is to provide a method
for operating an eccentric jaw crusher, wherein softer material
does not strongly connects to a crushing plate.
A still further object of the present invention is to provide a
method for operating an eccentric jaw crusher, wherein suitable
modes of crushing are easily obtained by changing operation of the
crusher in correspondence to the kinds of materials being crushed.
A still further object of the present invention is to provide a
method for operating an eccentric jaw crusher, wherein both abilities
of crushing are derived therefrom.
An eccentric jaw crusher according to the present invention has
two directions of rotation, in one of which a movable plate normally
rotates on a curve having a hysteresis, and in another of which
it reversely rotates thereon. That is, an eccentric shaft is rotated
normally and reversely. A selected point disposed on in the lower
portion of a movable plate moves on a hysteresis curve. Such a hysteresis
curve looks like a straight line, but upon close inspection, is
found to be formed with an upper portion and a lower portion. The
upper portion of the curve is continuously connected at a top dead
point and a bottom dead point to the lower portion of the curve.
Such a curve looks like a crescent or a prolate ellipsoid.
The curve has a major axis, which intersects with the surface of
the other crushing plate. The upper portion and the lower portion
of the curve are mutually divided by the major axis. The angle between
the major axis and the surface of the other crushing plate is to
30 degrees from 10 degrees. The speed of the moving point is very
slow in the regions of the dead points. Particularly, the speed
is zero at the dead points and the differential of the velocity
is very large.
The movable crushing plate which moves upward on the upper portion
of the curve approaches the region of the top dead point toward
the other plate with a small angle formed between the surface and
the direction of the motion and then approaches at the top dead
point toward the other plate with a larger angle formed therebetween.
Such motion is called normal rotation and allows hard materials
to be effectively crushed.
The moving crushing plate which moves upward on the lower portion
of the curve approaches the region of the bottom dead point toward
the other plate with a small angle formed between the surface and
the direction of the motion and then approaches at the bottom dead
point towards the other plate with a larger angle formed therebetween.
Such motion is called reverse rotation and allows softer materials
to be effectively crushed. Such reverse rotation has ability to
remove softer material adhesively connected to the other plate.
This ability allows the machine to be continuously operated without
stopping the machine and without exchanging one machine (crusher)
for another machine (crusher)
It is also advantageous to shift the position at which a toggle
plate is swingingly supported. Such shift is able to change the
angle between the major axis of the hysteresis curve and the surface
of the other crushing plate. The shift enables the hysteresis curve
to be varied, the angle of the major axis being varied at the same
time. The angle between the vector of velocity of the moving point
and the fixed plate can be varied at both dead points. Such variation
could make the crushing possibility rich.
A shifting means for shifting the toggle plate is referred to as
a selecting means. The selecting means comprises a toggle seat having
a multiple of hollows for pivotably supporting the toggle plate,
the hollows being located at respective positions which are different
from each other. Such hollows may be located on the jaw side toggle
seat or the machine body side toggle seat. Such toggle seat is fixed
to the machine body, thereby it can have a strong structure.
A BRIEF DESCRIPTION OF THE DRAWINGS FIGURES
FIG. 1 is a front view of an embodiment of a jaw crusher according
to the present invention.
FIG. 2 is a horizontal side view of the jaw crusher of FIG. 1.
FIG. 3 is a detailed front view of a part of the described jaw
crusher
FIG. 4 is a top view of a toggle plate.
FIG. 5 is a side view of the toggle plate of FIG. 4.
FIG. 6 is a top view of a suspending means employed in the jaw
crusher.
FIG. 7 is a front view of the suspending means shown in FIG. 6.
FIG. 8 is a front view similar to FIG. 7 in which the toggle plate
is moved in.
FIG. 9 is a sectional front view of crushing plates.
FIGS. 10(a) and (b) are graphs showing hysteresis curves and directions
of rotation.
FIG. 11 is a front sectional view showing an aspect of crushing
a hard stone.
FIG. 12 is a front sectional view showing an aspect of crushing
a softer material.
FIG. 13 is a graph showing functions of velocity.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
An embodiment of an eccentric jaw crusher according to the present
invention is described in the following. FIGS. 1 and 2 illustrate
an ordinal eccentric jaw crusher for which the present invention
is applied. The illustrated jaw crusher is called a single-toggle
type of jaw crusher. A machine body 1 of the jaw crusher is rigidly
made of steel plates. Two bearings 2 are fixedly mounted on the
machine body 1. A rotating driving shaft 3 is rotatably supported
by bearings 2. A driving wheel 4 and a flywheel 5 are respectively
mounted on both side portions of driving shaft 3.
Driving wheel 4 can accumulate a large quantity of energy for crushing.
Driving wheel 4 and flywheel 5 are driven by means of a driving
motor (not shown). A hydraulic motor is better applied for the driving
motor. The hydraulic motor has a sufficiently large output power,
the supply of which is prompt, and has a sufficient ability to absorb
a strong impact. Such a hydraulic motor generally has a reverse
mechanism, for which a valve is generally equipped.
An eccentric shaft 6 is rotatably mounted on driving shaft 3. There
is provided a short distance between the center of driving shaft
3 and the center of eccentric shaft 6. A swinging jaw 7 is pivotably
mounted on eccentric shaft 6 and swings around the axis of eccentric
shaft 6. The upper potion of swinging jaw 7 is supported by eccentric
shaft 6. An eccentrically-rotable-supporting means for supporting
eccentrically the upper portion of swinging jaw 7 includes eccentric
shaft 6 and machine body 1.
As illustrated in FIG. 3 movable tooth side hollow 8 is situated
in the lower right side of swinging jaw 7. Movable tooth side hollow
8 forms a first defined portion or point. A toggle block 9 is mounted
on machine body 1. A machine body side hollow 11 is situated on
toggle block 9. Machine body side hollow 11 faces in the bevel direction
toward movable tooth side hollow 8.
Machine body side hollow 11 forms a second defined portion or point.
A toggle plate 12 swingingly lies between movable tooth side hollow
8 of swinging jaw 7 and machine body side hollow 11 of toggle block
9. As illustrated in FIGS. 4 and 5 toggle plate 12 is made of a
rectangular metal plate and formed long in the axial direction of
driving shaft 3.
Movable tooth side hollow 8 machine body side hollow 11 and toggle
plate 12 respectively extends in the axial direction parallel to
the axial direction of driving shaft 3. One side portion of toggle
plate 12 pivotably connects to movable tooth side hollow 8 while
another side portion of toggle plate 12 pivotably connects to machine
body side hollow 11. A first receiving hollow 13 is formed on toggle
block 9. Receiving hollow 13 receives a machine body side toggle
seat 14. Machine body side toggle seat 14 forms a machine body side
supporting body for supporting swingingly or pivotably one side
portion of toggle plate 12. Machine body side hollow 11 is formed
on the front surface of machine body side toggle seat 14.
Machine body side hollow 11 includes an upper machine body side
hollow 11T and a lower machine side hollow 11B. Upper machine body
side hollow 11T and lower machine side hollow 11B are situated on
the bevel plane inclining against a vertical plane. Both hollows
11B, 11T are formed cylindrically.
A second receiving hollow 15 is formed on the rear portion of the
lower portion of swinging jaw 7. Second receiving hollow 15 receives
a movable tooth side toggle seat 16. Tooth side toggle seat 316
forms a movable tooth side supporting body for supporting swingingly
or pivotably another side portion of toggle plate 12. Movable tooth
side hollow 8 is formed on the front surface of tooth side toggle
seat 16.
The jaw crusher includes two tooth plates. As illustrated in FIG.
1 a movable tooth plate 21 is fixed on the front surface of swinging
jaw 7 a fixed tooth plate 22 being fixed on the front portion of
machine body 1. The front surface of movable tooth plate 21 faces
against the front surface of fixed tooth plate 22. The front surface
of movable tooth plate 21 is inclined with respect to the front
surface of fixed tooth plate 22. A V-shaped crushing space is formed
between both surfaces, the lower portion of the crushing space being
narrower than the upper portion thereof. Into the upper portion
are deposited materials to be crushed. Movable tooth plate 21 and
fixed tooth plate 22 respectively extends in the axial direction
and are substantially coextensive there along. Both movable tooth
plate 21 and fixed tooth plate 22 respectively, have the teeth,
which are respectively formed lattice-like.
Toggle block 9 is securely fixed to a reactive plate 23 which
strongly stands on machine body 1. The weight of the swinging jaw
7 acts on toggle block 9 through tooth side toggle seat 16 toggle
plate 12 and machine body side toggle seat 14. Toggle block 9 forced
as such, is pressed against reactive plate 23. Two bodies of first
hydraulic cylinders 24 are mounted on machine body 1 being able
to incline. First hydraulic cylinders 24 are able to push toggle
block 9 in the forward direction. A pin 26 is fixed on toggle block
9 being positioned in the axial direction between both side portions
of toggle block 9. To pin 26 are connected the movable portions
of first hydraulic cylinders 24. Toggle block 9 being pushed in
the forward direction, a plate-like spacer 29 can be inserted between
toggle block 9 and reactive plate 23.
A tension rod 31 is pivotably and swingingly mounted on the lower
portion of swinging jaw 7. A compressed coil spring 37 lies between
a flange 32 and a spring receiving body 33. Flange 32 is formed
as a rear end portion of tension rod 31 while spring-receiving
body 33 is fixedly mounted on the lower portion 34 of machine body
1 so that tension rod 31 penetrates coil spring 37.
A second hydraulic cylinder 35 is mounted on the upper portion
of machine body 1. Pressure receiving portions 36 are formed on
the side portions of swinging jaw 7. Pressure receiving portion
36 receives pressure of second hydraulic cylinders 35. Second hydraulic
cylinders 35 can pivotably drive swinging jaw 7 in the clockwise
direction in FIG. 3.
FIGS. 6 and 7 illustrates a suspending means for varying inclining
positions of toggle plate 12. A triangular suspending metal plate
41 is fixed on toggle block 9 by bolts at fixed points. From the
two points of suspending metal plate 41 are suspended two suspension
bolts 43. Eye-bolts 45 are fixed on toggle plate 12 at two points.
Into eye-bolts 45 are respectively inserted the respective hooks
of suspension bolts 43.
As illustrated in FIG. 8 swinging jaw 7 is pivotably driven by
second hydraulic cylinder 35 in the clockwise direction, toggle
plate 12 being suspended by suspension bolts 43. The machine body
side portion of toggle plate 12 is moved downward by screwing suspension
bolts 43. The pressure of second hydraulic cylinder 35 being reduced
permits swinging jaw 7 to pivot in the anticlockwise direction,
whereby the machine body side portion of toggle plate 12 is received
into lower machine side hollow 11B. As such, the heavy toggle plate
12 is easily moved.
Rotating driving shaft 3 being driven, eccentric shaft 6 rotates
around rotating driving shaft 3. Swinging jaw 7 swinging around
upper machine body side hollow 11T, a selected point in the region
of movable tooth side hollow 8 moves in general on a circular arc.
A stone of large size is inserted between movable tooth plate 21
and fixed tooth plate 22 into the upper portion of the crushing
space V. It is inserted and then pressed at three points in principle,
as illustrated in FIG. 11 (only two points appear.), thereby the
stress concentrates on the three points. The crushable article inserted
between movable tooth plate 21 and fixed tooth plate 22 is forced
in the directions perpendicular to the surface of movable tooth
plate 21 and the surface of fixed tooth plate 22. The stress generated
by such pressing distributes in the three dimensions to be an inner
stress in the article. The crushable article inserted between movable
tooth plate 21 and fixed tooth plate 22 is forced also in the direction
parallel to the surface of movable tooth plate 21 and the surface
of fixed tooth plate 22. The intensity of the inner stress instantly
generates two stressed clusters inside the article, thereby the
article is divided into two pieces. Such divided articles of smaller
size fall into the middle portion of the crushing space V. The articles
in the middle space are divided in the same manner as described
above to be of still further smaller size.
As illustrated in FIG. 9 the moving point W of the lower end portion
of movable tooth plate 21 which is fixed to swinging jaw 7 moves
on a prolate ellipsoid-like hysteresis curve, approximately moving
on a straight line inclining against the surface of fixed tooth
plate 22. Another moving point Q of the upper portion moves on a
more elliptic curve.
Major axis 40 is defined as a straight line linking the dead top
point T to the dead bottom point B. FIG. 13 shows functions of velocity.
In FIG. 13 the horizontal axis shows the distance of movement of
the moving point W, the vertical axis showing the velocity of the
moving point W. The graduation of the horizontal axis divides one
cycle of the hysteresis-curve into 8 portions. The velocity is commonly
zero or almost zero in value at the dead points. A selected point
in the region of the lower end point W moves on a hysteresis curve
which is almost the same in size and in shape as the curve on which
the moving point W moves.
The curve is generally seen as sharp, but is locally observed to
be smooth. The differential function of velocity is continuous,
having no singular point at which the velocity is constant.
The parameters defining such shape of the curve are as follows:
eccentricity (the distance between the center of eccentric shaft
6 and the center of driving shaft 3), the distance between the center
of eccentric shaft 6 and upper machine body side hollow 11T or lower
machine body side hollow 11B, the distance between the center of
eccentric shaft 6 and the moving point W, the length (width) of
toggle plate 12 and the angles defined by the three points of the
above centers and point. Some of the parameters depend on the angle
.beta. (shown in FIG. 3) between toggle plate 12 and a reference
surface, for example, a horizontal plane, and the distance of the
center of eccentric shaft 6 and the center of movable tooth side
hollow 8 particularly depending on the angle .beta.
The angle .alpha. between the direction of the velocity of the
moving point W at the dead point and the surface of the plate 22
is a function of the angle .beta.. As shown in FIG. 10 the angle
.beta. between the direction of the vector A and the surface 45
of fixed tooth plate 22 is approximately 80 degrees, being smaller
than an angle .theta.. The vector A at the top side dead point is
almost the same as the vector C at the bottom side dead point. Both
vectors are slightly different from each other.
The value of the velocity is very small at the bottom dead point
B and the top dead point T, but it becomes the maximum values in
the intermediate portion between the bottom dead point B and the
top dead point T. The moving point W is quickly accelerated to have
a large velocity. The direction in which the moving point W on the
top dead point moves toward the bottom dead point is shown by the
arrow A as shown in FIG. 10(a). Rotation in such direction is called
normal rotation in this specification.
Stones are harder than materials such as asphalt. In this specification,
four words are used for four materials, those are, harder stones,
soft stones, harder lumps of asphalt, soft lumps of asphalt.
One angle .beta. in the case that one end of toggle plate 12 is
positioned at upper machine body side hollow 11T is different from
another angle .beta. in the case that the end of toggle plate 12
is positioned at lower machine body side hollow 11B. The angle .alpha.
is a function of the angle .beta..
It is supported by the inventor's experiments that a larger angle
.beta. is apt to be suitable for crushing harder stones, a small
angle .beta. being apt to be suitable for crushing soft stones.
Some stones do not follow such inclination. An operator may select
the angle .beta. with reference to the kind of material.
The suspending means, as shown in FIG. 6 and 7 is available for
selecting the angle .beta.. Toggle plate 12 is too heavy to be lifted
up by an operator without any danger. The suspending means makes
it easy and safe to change the angle .beta.. Machine body side toggle
seat 14 is directly fixed to and supported by machine body 1. In
other words, machine body side toggle seat 14 is not fixed to machine
body through any resilient material, thereby the structure for supporting
toggle plate 12 is strongly formed. Spacer 29 is made of strong
material equivalent to that of the machine body. Spacer 29 is not
supported by first hydraulic cylinder 24 but by machine body 1
thereby spacer 29 is conceived as a part of machine body 1 in respect
to the supporting means.
As illustrated in FIG. 10(a) and (b), the curve is divided into
two portions by major axis 40. In the motion shown in FIG. 10 (a),
the point W moves upward on the upper portion of the hysteresis
curve. That is, the point W is on the upper portion 41 of the hysteresis
curve, moving upward in the direction to the top dead point T from
the bottom dead point B. On the other hand, the point W moves downward
on the lower portion of the hysteresis curve. That is, the point
W is on the lower portion 42 of the hysteresis curve, moving downward
in the direction to the bottom dead point B from the top dead point
T.
In the motion shown in FIG. 10(b), the point W moves downward on
the upper portion 41 of the hysteresis curve. That is, the point
W is on the upper portion 41 of the hysteresis-curve, moving downward
in the direction to the bottom dead point B from the top dead point
T. On the other hand, the point W moves upward on the lower portion
42 of the hysteresis curve. That is, the point W is on the lower
portion 42 of the hysteresis curve, moving upward in the direction
to the top dead point T from the bottom dead point B.
Fixed tooth plate 22 which is a set of the points respectively
moving on the respective ellipsoid-like hysteresis curve, functions
in general as mentioned above. It is significant in a crusher according
to the present invention to analyze the nature in the differentiation
as to the motion. As shown in FIG. 10(a), a conventional crusher
is operated so that the point W rotates in the anti-clockwise direction.
Such a conventional direction of rotation is reasonable as described
below.
The major axis 40 appearing in FIG. 10(a), against the surface
45 is inclined at angle .theta. so at the crushed stone crushed
at the dead point T is pushed into the lower portion of the space
V. In such region, the displacement of the moving point is very
small. During this motion of the very small displacement, the whole
energy of the flywheel is instantly transmitted to the stone to
be crushed. Such transmitted energy is called impact energy.
After the initial crushing, that is, after the moving point W passing
the top side dead point, movable tooth plate 21 approaches the fixed
tooth plate 22 continuously giving energy to the stone so that
the is divided into two clusters. From such principle of crushing,
it has been thought that a jaw crusher is not suitable for crushing
softer materials but only for crushing hard materials. For softer
materials that are not pressed at points but pressed between surfaces,
as shown FIG. 12 are plasticly destroyed.
The inventor noticed that a method for crushing in the direction
of rotation as shown in FIG. 10(b) is, nevertheless, reasonable
for crushing softer materials, asphalt for example. The moving point
W, as shown in FIG. 10(b), approaches against fixed tooth plate
22 at the bottom side dead point with the angle .alpha. given. The
crushing mechanism is same at the top side dead point as at the
bottom dead point in the respect that crushing effects are produced
when the moving point approaches to fixed tooth plate 22. Soft materials
are initially crushed at the bottom dead point. Initially crushed
materials are completely crushed. In other words, initially crushed
materials are easily divided by a peeling force. Such peeling force
is brought out during the course the moving point W moves upwards
on the lower curve portion 42 the space between the movable tooth
plate 21 and fixed tooth plate 22 being narrower.
However, the initially crushed materials pushed up into the wider
portion of the space V. They are not still pressed but merely peeled
themselves by the above mentioned peeling force, thereby they are
not formed plastic and do not adhere to the tooth plates 2122.
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