Abstrict A jaw crusher designed to break a non-rigid object, e.g., asphalt,
into pieces of desired size without causing the object to be undesirably
mashed by changing the motion of a movable tooth plate relative
to a fixed tooth plate. The jaw crusher includes a fixed tooth plate
(16), a swing jaw (8), a movable tooth plate (15), and a toggle
plate (10). Motion of a lower end portion of the movable tooth plate
(15) which is on an approximately circular locus satisfies the conditions
that the relative angle between a straight line connecting the lower
and upper end points of the approximately circular locus and the
fixed tooth plate (16) is not smaller than 20.degree., and that
the distance between the lower and upper end points is not shorter
than 50 mm.
Claims What is claimed is:
1. A jaw crusher for breaking a non-rigid object, said jaw crusher
comprising:
a body (1);
a fixed tooth plate having a flat surface (16) secured to said
body (1);
a swing jaw (8) adapted to swing relative to said fixed tooth plate
(16);
a movable tooth plate (15) secured to said swing jaw (8) at an
acute angle to said fixed tooth plate (16) to define a crushing
space for breaking an object of crushing between said movable tooth
plate (15) and said fixed tooth plate (16);
an eccentric rotating shaft (7) provided on said body (1) to swingably
support an upper end portion of said swing jaw (8) and to rotate
eccentrically; and
a swing support member (10) provided between said body (1) and
said swing jaw (8) so as to be swingable relative to both said body
(1) and said swing jaw (8);
wherein motion of a lower end portion of said movable tooth plate
(15) which is on an approximately circular locus satisfies the following
conditions:
(U1) an angle between a surface of said fixed tooth plate (16)
and a straight line connecting lower and upper end points of the
approximately circular locus on which said lower end portion of
said movable tooth plate (15) moves is not smaller than 20.degree.;
and
(U2) the distance between said lower and upper end points is not
shorter than 50 mm.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a jaw crusher for breaking a non-rigid
object like asphalt. More particularly, the present invention relates
to a jaw crusher suitable for breaking a viscous, non-rigid object,
e.g., asphalt pavement wastes.
2. Description of the Background Art
Jaw crushers are known and used as machines for breaking rocks,
asphalt pavement wastes, concrete scraps, etc. into pieces of desired
size. These days, a large amount of concrete scrap and asphalt pavement
waste are produced by dismantling of concrete buildings, repair
of asphalt pavements, etc. Treatment of these wastes, particularly
in urban areas, gives rise to a social problem because of the generation
of noise and dust during the treatment, difficulty in securing a
place for dumping wastes, a high cost of waste transportation, etc.
For this reason, these wastes are desired to be speedily treated
and reused at or near the site where the wastes are produced, as
much as possible.
It will be advantageous if asphalt pavement wastes can be broken
into pieces which are sufficiently small in particle size to be
reused as aggregates or other similar material by using a conventional
jaw crusher capable of efficiently breaking a rigid object, e.g.,
rocks, into pieces of desired size. However, if a conventional jaw
crusher, which has been developed to break rocks or other rigid
objects since the beginning of the development thereof, is used
for breaking asphalt pavement wastes as it is, the asphalt pavement
wastes may be undesirably mashed or stick to the movable and fixed
tooth plates and fail to drop from the V-shaped crushing space defined
between the two tooth plates. Thus, the conventional jaw crusher
becomes unable to break the object of crushing. Moreover, it is
almost impossible for the conventional machine to crush asphalt
pavement wastes favorably for reuse of them. At present, conventional
jaw crushers are reluctantly used as they are for breaking asphalt
pavement wastes, and reuse of asphalt pavement wastes is not considered.
Incidentally, jaw crushers for breaking rocks include various types
which may be most suitably selected for each particular use in conformity
to the kind of rock to be crushed and the particle size of pieces
into which rocks are to be broken. We carried out an experiment
by breaking asphalt pavement wastes with these various types of
conventional jaw crusher, and found a new way of improving the conventional
jaw crushers for effectively breaking asphalt pavement wastes.
SUMMARY OF THE INVENTION
The present invention has been accomplished on the basis of the
above-described technical background, and aims at attaining the
following object.
It is an object of the present invention to provide a jaw crusher
for breaking a non-rigid object like asphalt, which is designed
to break asphalt or other non-rigid object into pieces of desired
size without causing the object to be undesirably mashed or stick
to the movable and fixed tooth plates by changing the motion of
the movable tooth plate relative to the fixed tooth plate.
To attain the above-described object, the present invention provides
a jaw crusher for breaking a non-rigid object, e.g., asphalt. The
jaw crusher has a body (1), and a fixed tooth plate (16) is secured
to the body (1). A swing jaw (8) swings relative to the fixed tooth
plate (16). A movable tooth plate (15) is secured to the swing jaw
(8) at an acute angle to the fixed tooth plate (16) to define a
crushing space for breaking an object of crushing between the movable
tooth plate (15) and the fixed tooth plate (16). An eccentric rotating
shaft (7) is provided on the body (1) to swingably support the upper
end portion of the swing jaw (8) and to rotate eccentrically. A
swing support member (10) is provided between the body (1) and the
swing jaw (8) so as to be swingable relative to both the body (1)
and the swing jaw (8). Motion of the lower end portion of the movable
tooth plate (15) which is on an approximately circular locus satisfies
the following conditions (U1) and (U2):
(U1) the relative angle between a straight line connecting the
lower and upper end points of the approximately circular locus and
the fixed tooth plate (16) is not smaller than 20.degree.; and
(U2) the distance between the lower and upper end points is not
shorter than 50 mm.
In the jaw crusher for breaking a non-rigid object, e.g., asphalt,
according to the present invention, the lower end portion of the
movable tooth plate (15) moves on a circular locus. The motion takes
place in approximately straight line from the lower end point to
the upper end point of the circular locus. The angle of the straight-line
locus relative to the fixed tooth plate (16) is not smaller than
20.degree.. In addition, the stroke of this motion is not smaller
than 50 mm. By virtue of such motion, an object of crushing is strongly
held and pressed between the two tooth plates, and in this state,
it is subjected to shearing force. Thus, the object is broken into
particles of desired size without being mashed. Accordingly, there
is no likelihood that the object of crushing will stick to the two
tooth plates, causing the machine to fall into a failure of crushing
operation.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present
invention will become more apparent from the following description
of the preferred embodiment thereof, taken in conjunction with the
accompanying drawings, in which like reference numerals denote like
elements, and of which:
FIG. 1 is a front view of one embodiment of the jaw crusher according
to the present invention;
FIG. 2 is a plan view of the embodiment shown in FIG. 1;
FIG. 3 shows an orthogonal coordinate system for explanation of
the operation of the embodiment;
FIG. 4 is a graph showing experimental results for comparison between
an experimental jaw crusher of the present invention and conventional
comparative jaw crushers; and
FIG. 5 is a graph showing data for comparison between the jaw crusher
of the present invention and the conventional jaw crushers.
DETAILED DESCRIPTION OF THE EMBODIMENT
One embodiment of the present invention will be described below
with reference to the accompanying drawings.
FIGS. 1 and 2 show one embodiment of the jaw crusher for a non-rigid
object, e.g., asphalt, according to the present invention. FIG.
1 is a front view, and FIG. 2 is a plan view. These figures show
a crusher that is generally called "single-toggle type jaw
crusher" (hereinafter referred to as "jaw crusher").
The jaw crusher has a body 1 that is made of steel plate. The body
1 is provided with two bearings 2. A driving shaft 3 is rotatably
supported by the bearings 2. A pulley 4 for driving the shaft 3
is attached to one end of the shaft 3. The outer periphery of the
pulley 4 is provided with a plurality of V-belt grooves 5. V-belts
(not shown) are engaged between the V-belt grooves 5 of the pulley
4 on the one hand and a plurality of V-belt grooves on the other,
which are provided on a pulley (not shown) attached to the output
shaft of a driving motor (not shown).
A flywheel 6 is attached to the other end of the driving shaft
3. An eccentric rotating shaft 7 is eccentrically provided on a
rotating member (not shown) which rotates together with the driving
shaft 3 as one unit. The upper end portion of a swing jaw 8 is attached
to and rotatably supported by the eccentric rotating shaft 7. The
rear side (the right-hand side as viewed in FIG. 1) of the lower
end portion of the swing jaw 8 is provided with a recess 8a. A plate
retainer 9 which is secured to the body 1 is also provided with
a recess 9a. A toggle plate 10 as a swing support member is stretched
between the recess 8a of the swing jaw 8 and the recess 9a of the
plate retainer 9.
A pulling rod 11 is rotatably attached to the lower end of the
swing jaw 8. A compression coil spring 14 is provided between a
collar 12 attached to the rear end of the pulling rod 11 and a spring
retainer 13 which is secured to the body 1 so that the pulling rod
11 extends through the spring retainer 13.
A movable tooth plate 15 which is in the form of a flat plate is
secured to the front side of the swing jaw 8. A fixed tooth plate
16 which is also in the form of a flat plate is secured to a slightly
inclined wall surface inside the body 1 in opposing relation to
the movable tooth plate 15. The fixed tooth plate 16 is set at an
acute angle to the movable tooth plate 15 to define therebetween
a crushing space with a V-shaped cross-sectional configuration for
breaking an object of crushing.
The operation of the above-described embodiment will be explained
below. The driving shaft 3 is driven to store energy in the flywheel
6. The swing jaw 8 which is supported by the toggle plate 10 performs
swing motion under the control of the toggle plate 10. Since the
swing jaw 8 is constantly pulled by the compression coil spring
14 the toggle plate 10 will not separate from the swing jaw 8 or
the plate retainer 9. Accordingly, the point (approximately one
point) of rolling contact between the toggle plate 10 and the recess
8a of the swing jaw 8 rotates about the point (approximately one
point) of rolling contact between the toggle plate 10 and the recess
9a of the plate retainer 9.
FIG. 3 shows an orthogonal coordinate system (x, y) for analysis
of the motion of an end point on the movable tooth plate 15. The
origin O represents the axis of the driving shaft 3 and the point
P (D, 0) is the point of rolling contact between the toggle plate
10 and the recess 9a of the plate retainer 9. The point Q (x, Y)
is the point of rolling contact between the toggle plate 10 and
the recess 8a of the swing jaw 8 and the point R (x, y) is a specific
end point on the movable tooth plate 15. The amount of eccentricity
of a point U on the swing jaw 8 in the vicinity of the eccentric
rotating shaft 7 is taken as a unit length, which is assumed to
be 1 (e.g., 10 mm). The point U is on a circle with a radius 1 which
is centered at the origin O as viewed in FIG. 1. Accordingly, the
coordinates of the point U are determined by ##EQU1## where t=cos(Z),
and the angle Z is continuous in the range of from zero radian to
6.28 radian. Since the point Q is on a circle with radius R which
is centered at the point P, the coordinates X, Y of the point Q
satisfy the following equation (1):
Since both the points U and Q are fixed points on the swing jaw
8 the distance between the points U and Q is constant, which is
represented by L. From the Pythagorean theorem (the theorem of three
squares), the following equation (2) is obtained: ##EQU2##
Since both the points R and Q are fixed points on the swing jaw
8 the distance between the points R and Q is constant, which is
represented by s. From the Pythagorean theorem, the following equation
(3) is obtained:
Assuming that the angle of inclination of a straight line connecting
the points R and Q is F, the inclination of the straight line RQ
is tan(F). Since this straight line passes through the point R (x,
y), the straight line RQ may be expressed by
Assuming that the angle UQR=G and the angle QUW=K (the point W
is shown in FIG. 3), the following equation (5) is obtained:
If tan(F)=(sin(F))/(cos(F)) is calculated, the following equation
(6) is obtained: ##EQU3##
From equations (3) and (4),
From equation (7), ##EQU4##
The coordinates (X, Y) may be obtained from equations (1) and (2)
as follows: ##EQU5## where A and B are defined by the following
equations (10-1) and (10-2): ##EQU6##
Since tan(F)=tan(G-K)=tan(G)-tan(K)/(1+tan(G).multidot.tan(K)),
tan(F) may be obtained from this relationship and equation (6) as
follows: ##EQU7##
If tan(F) thus obtained, together with X and Y which are obtained
by substituting equations (10-1) and (10-2) into equations (9-1)
and (9-2), is substituted into equations (8-1) and (8-2), the coordinates
(x, y) of the end point R on the movable tooth plate 15 are represented
by the angle G, the length R, the length L and the length s, which
are constants, and the variable t. Thus, there is only one variable.
Although the functional relation between x and y cannot readily
be obtained, x and y are represented by the variable t(=cos(Z))
alone. Accordingly, the locus of motion of the end point R can roughly
be observed by plotting (x, y) obtained by substituting values for
Z which are obtained by dividing the angle range of from zero radian
to 6.28 radian into, for example, 100 equal partitions (it should
be noted that the .+-. signs in the above equations are not double
signs in same order).
The locus of the point R in FIG. 3 is obtained under the conditions
of G=105.degree., D=68.3 L=102.0 R=56.0 s=35.2 and the eccentricity
is 10 mm. If the coordinate system (x, y) is translated to the point
R to form a coordinate system (X', y') with the point R defined
as origin and coordinates (X', y') are printed out with the above-described
angle range divided into 10 equal partitions, the following values
are obtained (only for 1/4 i.e., 90.degree.):
______________________________________ x' y' ______________________________________
0 0 1.2 0.6 2.5 1.2 4.1 1.8 5.9 2.3 7.7 2.8 9.8 3.2 12.0 3.7 14.3
4.2 16.7 4.5 19.7 4.8 ______________________________________
If the number of partitions is increased to observe the motion
even more finely, it will be understood that the motion is relatively
slow at both ends of the circular locus but relatively fast at the
intermediate portion. Such a locus is approximately in the shape
of a circular arc (see Japanese Patent Application Post-Exam. Publication
No. 36-2641 (1961)). However, detailed observation reveals that
the locus has hysteresis, that is, there is a difference in locus
between the go and return strokes of the reciprocating motion, and
that the locus has a shape intermediate between an elliptic shape
and a crescent shape. The two end points are sharp.
FIG. 4 is a graph showing experimental results for comparison between
conventional comparative jaw crushers and an experimental jaw crusher
of the present invention. In the graph, crescent motion performed
by a specific point (R in FIG. 3) on the movable tooth plate 15
in each crusher between the lower and upper end points is approximately
represented by a straight line. The axis of ordinates represents
the vertical direction, and the axis of abscissas the horizontal
direction. For reference to FIG. 3 a coordinate system (x', y')
is entered in FIG. 4. Data on 5 different types of jaw crusher,
which are different in parameters such as the amount of eccentricity,
are shown by the lines L.sub.1 L.sub.2 L.sub.3 L.sub.4 and L.sub.5.
The lines L.sub.2 to L.sub.5 show the conventional jaw crushers,
respectively. The line L.sub.1 shows an experiment in which the
crusher has an eccentricity of 16 mm, and a relatively long stroke
of motion, that is, 64 mm. In addition, the angle at which the tip
of the movable tooth plate 15 goes toward the fixed tooth plate
16 is relatively large, that is, 20.degree.. The line L.sub.2 shows
an experiment in which the stroke of motion is not so long (42 mm),
and the angle at which the movable tooth plate 15 goes toward the
fixed tooth plate 16 is relatively small (18.5.degree.). The line
L.sub.3 shows an experiment in which the stroke of motion is short
(30 mm), and the angle at which the movable tooth plate 15 goes
toward the fixed tooth plate 16 is relatively small (18.degree.).
The line L.sub.4 shows an experiment in which the stroke of motion
is not so long (49.5 mm), but the angle at which the movable tooth
plate 15 goes toward the fixed tooth plate 16 is considerably large
(23.degree.). The line L.sub.5 shows an experiment in which the
stroke of motion is considerably long (61 mm), but the angle at
which the movable tooth plate 15 goes toward the fixed tooth plate
16 is relatively small (18.5.degree.).
FIG. 5 is a graph showing the relationship between the relative
angle (at which the end point of the movable tooth plate 15 goes
toward the fixed tooth plate 16), which is plotted along the axis
of ordinates, and the stroke (the linear distance between the lower
and upper extremities of the motion of the end point on the movable
tooth plate 15), which is plotted along the axis of abscissas, for
each of the above 5 examples. The example of the present invention
is within a region in which the stroke is not shorter than 50 mm
and the relative angle is not smaller than 20.degree.. However,
the other 4 examples are not in this region (hereinafter referred
to as "the region of the present invention").
According to-the experimental results, when a jaw crusher which
is in a region other than the region of the present invention is
used to crush asphalt, the asphalt is not broken into particles
but undesirably mashed or caused to stick to the movable and fixed
tooth plates 15 and 16 causing the machine to fall into an operation
failure. In contrast, the experimental machine that is within the
region of the present invention is capable of breaking asphalt into
particles which can be reused as aggregates, in which substantially
no stickiness is observed. It will be clearly understood from the
experimental results of the 5 examples that when the relative angle
is large, the asphalt crushing performance is good, and when the
stroke is large, the crushing performance is also good; however,
when only the relative angle or the stroke is large, the crushing
performance is not good.
It has been found from the experimental results that the asphalt
crushing performance is good when the following conditions (U1)
are (U2) satisfied:
(U1) the relative angle between the straight line connecting the
lower and upper end points of the approximately circular locus and
the fixed tooth plate (16) is not smaller than 20.degree.; and
(U2) the distance between the lower and upper end points is not
shorter than 50 mm.
This may be presumed as follows: Energy required for crushing is
stored in asphalt by the motion (U1) of large relative angle. A
rigid object can be crushed by this energy, but the crushing operation
involves some unreasonableness. On the other hand, a non-rigid object
can be crushed substantially reasonably. Next, the motion (U2) of
large stroke exerts force on asphalt so that the fixed tooth plate
side and the movable tooth plate side of the asphalt are largely
displaced relative to each other. Presumably, asphalt is sheared
by this force.
The validity of the above presumption has also been proved by an
experiment carried out on relatively soft rocks (e.g., rocks which
have been weathered). It should be noted that the upper limit of
the stroke, the upper limit of the relative angle, and the correlation
between these two upper limits are limited by design conditions
such as the power of the prime mover used, the strength of the machine
body, the size of the machine body, etc.
The present invention provides the following advantageous effect:
A conventional jaw crusher can be used to crush a non-rigid object
for the purpose of reusing it simply by changing parameters.
Although the present invention has been described through specific
terms, it should be noted here that the described embodiment is
not necessarily exclusive and that various changes and modifications
may be imparted thereto without departing from the scope of the
invention which is limited solely by the appended claim. |