Abstrict An improved vertical shaft impact crusher, and in particular a
crusher having a shoe assembly attached to a rotatable table assembly,
the shoe assembly comprising a bracket, a shoe, and mounting bolts
for removably attaching the shoe to the bracket. The shoe has a
contact surface which engages a support surface of the bracket to
reduce shear forces in the mounting bolts during rotation of the
table assembly. The crusher also has a liner for protecting an outside
face of the bracket. The liner has spacers located on a mounting
surface which create a gap between the liner and the bracket, thereby
reducing a prying action caused by uneven deflections in the mounting
bracket during rotation of the table assembly.
Claims What is claimed is:
1. In a vertical shaft impact crusher having a table assembly mounted
for rotation about a central axis, a shoe assembly comprising:
a shoe having a front guide surface, a rear attachment surface,
a contact surface extending transversely of the central axis, and
a threaded aperture formed in the attachment surface the threaded
aperture having a diameter;
a bracket adapted for attachment to the table assembly having a
front face, a rear face, an opening extending through the bracket
from the front face to the rear face, and a support surface extending
transversely of the central axis and facing the contact surface,
the bracket opening having a width normal to the central axis which
is greater than the threaded aperture diameter; and
a bolt passing through the bracket opening and threaded into the
threaded aperture of the shoe thereby to releasably secure the shoe
to the bracket;
wherein the bracket opening allows the bolt and shoe to slide radially
outwardly so that the contact surface of the shoe engages the support
surface of the bracket when the table assembly is rotated.
2. The crusher of claim 1 in which the shoe has a boss projecting
rearwardly from the attachment surface, the contact surface being
formed by an outer wall of the boss.
3. The crusher of claim 2 in which the bracket has a recessed
pocket formed in the front face, the support surface being formed
by an outer wall of the pocket.
4. The crusher of claim 1 in which the central axis extends vertically
and the opening in the bracket is formed as a horizontally extending
slot.
5. The crusher of claim 4 wherein the slot is adapted so that
as the support and contact surfaces engage contact between the bolt
and the bracket is prevented.
6. A vertical shaft impact crusher comprising:
a table assembly mounted for rotation about a central axis;
a shoe bracket attached to an upper surface of the table assembly,
the shoe bracket having an outside face extending transversely to
the central axis; and
a liner having a shielding surface facing away from the shoe bracket
outside surface and sized to substantially overlie the outside face
of the shoe bracket, a mounting surface substantially conforming
to the shape of, and facing toward, the shoe bracket outside surface,
and means for mounting the liner to the shoe bracket outside surface,
the mounting means including a spacer disposed between the shoe
bracket outside face and the liner mounting surface to form a gap
therebetween.
7. The crusher of claim 6 in which the shoe bracket outside face
further comprises a threaded aperture, the liner mounting means
comprises a bolt hole extending from the shielding surface to the
mounting surface and a bolt inserted through the bolt hole and into
the threaded aperture thereby to releasably attach the liner to
the bracket.
8. The crusher of claim 7 in which the spacer is disposed around
the bolt hole.
9. The crusher of claim 6 in which the spacer is located near
a top portion of the liner so that the gap is formed near at least
a top edge of the bracket.
10. The crusher of claim 6 in which the spacer has an annular shape.
11. The crusher of claim 6 in which the spacer comprises a washer.
12. The crusher of claim 6 in which the spacer is formed integrally
with the liner.
13. The crusher of claim 6 in which the spacer is formed separately
from the liner, the spacer being permanently attached to the mounting
surface.
Description FIELD OF THE INVENTION
The present invention relates to rock crushing apparatus, and more
particularly to vertical shaft impact crushers.
BACKGROUND OF THE INVENTION
Vertical shaft impact crushers are generally known in which centrifugal
force is used to hurl large rocks against an impact surface, thereby
to obtain smaller crushed rocks. Rock material is typically fed
into a rotating impeller which hurls the rock material against a
plurality of anvils disposed about the impeller. In the alternative,
the rotating impeller throws the rock material against a bed of
already crushed rock instead of the anvils. In either event, the
rock crusher processes relatively larger rock material into relatively
smaller crushed rock.
One important consideration in the design of rock crushers is the
extension of the useful life span of the equipment. It will be appreciated
that certain of the components come into direct contact with the
rock material and therefore are subject to wear. The wear components
are typically releasably attached to the rock crushing apparatus
so that they may be removed and replaced. Other components are intended
to be permanent, and therefore must be protected from direct contact
with the rock material. The non-wear components are usually more
permanently attached to the crusher apparatus.
For example, in a vertical shaft impact crusher of the "open
table" type, the rotating impeller comprises a generally flat
table having multiple shoe assemblies projecting from a top surface
of the table near its periphery. The shoe assemblies typically comprise
a support bracket attached to the table and a shoe releasably secured
to the bracket. Rock material is dropped near the center of the
table and, under centrifugal force, moves toward the periphery of
the table where the shoes direct the large rock material toward
an impact surface surrounding the table assembly, typically an anvil
ring. The table is mounted on a flywheel attached to a rotating
shaft. In this example, the shoes and anvil ring contact the rock
material and therefore are wear components which should be attached
to the crusher apparatus in such a manner that they are easily removed
and replaced. The table, flywheel, and shaft are shielded from direct
impact and therefore are more permanent, non-wear components.
Conventional rock crushers often use fasteners, such as bolts,
to attach the shoe to support bracket. In such an arrangement, bolt
holes extend through the bracket and corresponding threaded holes
are formed in the shoe. The bolt holes and threaded holes have substantially
the same size and are aligned so that bolts inserted therethrough
releasably secure the shoe to the bracket. It will be appreciated
that as the shoe assemblies are rotated by the table, a significant
shear force develops between the fixed bracket and removable shoe.
The shear force is quite large, particularly for heavier shoes,
and therefore a significant risk exists that the bolts will be sheared
and the shoes thrown.
In addition, conventional vertical shaft impact crushers often
have a liner to protect the bracket from rock material bouncing
off of the anvil ring. The liner is typically bolted in place and
covers an outside face of the bracket. As the table spins, the centrifugal
force acting on the shoe and bracket cause deflections in the bracket
which increase in magnitude proportional to the height of the bracket
above the upper surface of the table. The uneven deflections across
the height of the bracket act to pry the bottom of the liner away
from the bracket, thereby breaking the bolts from the bracket.
The present invention is provided to reduce the shear forces between
the bracket and the shoe and/or to reduce prying forces between
the bracket and the liner.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a shoe
assembly is provided in a vertical shaft impact crusher having a
table assembly mounted for rotation about a central axis. The shoe
assembly comprises a shoe having a front guide surface, a rear attachment
surface, a contact surface extending transversely of the central
axis, and a threaded aperture formed in the attachment surface.
The shoe assembly further comprises a bracket having a front face,
a rear face, an opening extending through the bracket from the front
face to the rear face, and a support surface extending transversely
of the central axis. A bolt is inserted through the opening and
threaded into the threaded aperture to thereby releasably secure
the shoe to the bracket. The support surface is disposed radially
outwardly of the contact surface so that the contact surface of
the shoe engages the support surface of the bracket when the table
assembly is rotated.
The shoe may have a boss projecting rearwardly from the attachment
surface so that an outer wall of the boss forms the contact surface.
The bracket may have a recessed pocket formed in the front face
sized to accept the boss, an outer wall of the pocket forming the
support surface. In addition, the opening in the bracket may be
formed as a horizontally extending slot to ensure that the contact
surface engages the support surface.
In accordance with another aspect of the present invention, a liner
is provided in a vertical shaft impact crusher having a table rotating
about a central axis and a bracket attached to an upper surface
of the table, the bracket having an outside face. The liner has
a shielding surface and a mounting surface, the shielding surface
being sized to substantially cover the outside face of the bracket,
and the mounting surface adapted for releasable attachment to the
outside face of the bracket. A spacer projects from the mounting
surface to thereby form a gap between the mounting surface of the
liner and the outside face of the bracket.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view in perspective of a vertical shaft impact
crusher in accordance with the present invention;
FIG. 2 is a side elevation view, in section, of a vertical shaft
impact crusher in accordance with the present invention;
FIG. 3 is a top plan view of the table assembly of the present
invention;
FIG. 4 is a side elevational view, in section, of the table assembly
taken along line 4--4 of FIG. 3;
FIG. 5 is a perspective view of a table in accordance with the
present invention having a plurality of brackets attached thereto;
5 FIG. 6 is a top plan view, in section, taken along line 6--6
of FIG. 4 of a shoe assembly of the present invention including
a liner.
FIG. 7 is a side elevation view of a liner in accordance with the
present invention.
FIG. 8 is a plan view, in section, of the liner taken along line
8--8 of FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring initially to FIG. 1 a vertical shaft impact crusher
of the present invention, indicated generally at 10 has a housing
12 with a housing cover 14 attached thereto. The housing cover 14
defines a feed opening 15 and a hopper 16 is attached to the housing
cover 14 at the feed opening 15. A separate motor housing 18 is
spaced from the housing 12 and houses a motor 20. As best illustrated
in FIGS. 1 and 2 the housing 12 is generally cylindrical and has
a central axis 22 extending vertically. A bearing assembly 24 is
locating inside the housing 12 the bearing assembly rotatably journaling
a shaft 26 having a table assembly 28 attached to an upper end.
The lower end of the shaft 26 carries a pulley 30 which is driven
by the motor 20 through a belt 32.
The table assembly 28 comprises a flywheel 34 a table 36 and
a table cover 38. According to the illustrated embodiment, the table
36 is bolted to the flywheel 34 while the table cover 38 is attached
to an upper surface of the table 36. A center portion of the table
cover 38 provides a landing surface 39 onto which rock material
entering the crusher 10 is deposited. The flywheel 34 engages the
shaft 26 so that the entire table assembly 28 rotates with the shaft.
The table assembly 28 may further comprise a reinforcing ring 70
attached to a bottom surface of the table 36. The reinforcing ring
70 may be adapted to allow a rim liner 76 to be attached to the
table assembly 28 to thereby protect an outer edge 37 of the table
36 from the crushing impact inside the crusher 10.
At least one shoe assembly 40 is attached to an upper surface of
the table assembly 28. As shown in FIGS. 3 and 6 each shoe assembly
40 comprises a bracket 42 and a removable shoe 44. In the currently
preferred embodiment, each bracket 42 is welded to the table assembly
28 near a periphery of the table 36 (FIG. 5). Each bracket 42 is
formed with a recess 46 located generally in a rear face of the
bracket and a pocket 48 located in a front face of the bracket.
A pair of openings 50 extend through the bracket 42 from the recess
46 to the pocket 48. As best shown in FIG. 6 the pocket 48 has
a support surface 47 extending transversely of the central axis
22.
Each shoe 44 is formed to be releasably attached to a corresponding
bracket 42. The shoe 44 has a front guide surface 54 and a rear
attachment surface 59. The guide surface 54 is curved and extends
generally radially from the central axis 22. The guide surface 54
has forward projecting upper and lower edges 56 58 (FIG. 4). A
boss 52 projects from the rear attachment surface 59 of each shoe
44 and is shaped to slidably fit inside the pocket 48 formed in
the bracket 42. A pair of threaded apertures 60 are formed in the
boss 52 and are positioned so that they are aligned with the bolt
holes 50 when the boss 52 is inserted in the pocket 48 as illustrated
in FIG. 6. A pair of bolts 62 (FIG. 3) are inserted through the
bolt holes 50 and into the threaded holes 60 to thereby releasably
secure the shoe 44 to the corresponding bracket 42. An outside edge
of the boss 52 forms a contact surface 53 extending transversely
of the central axis 22 for engaging the support surface 47 of the
bracket 42 as described in greater detail below.
An anvil ring 64 is located around a periphery of the housing 12
for providing an impact surface 66 for breaking incoming rock material
(FIG. 2). According to the illustrated embodiment, the anvil ring
64 comprises a plurality of individual anvils 64 spaced about the
interior of the housing 12. While the illustrated embodiment shows
an anvil ring 64 it will be appreciated that the impact surface
66 may be provided by other structure, such as previously broken
rock material accumulating on a rock shelf. Crushed rock collects
in a bottom portion of the housing 12 where a removal device (not
shown) carries the crushed rock out of the crusher 10.
In operation, rock material is dumped into the hopper 16 where
it passes through the feed opening 15 to be deposited on the landing
surface 39 of the table assembly 28. In the illustrated embodiment,
the motor 20 drives the shaft 26 so that the attached table assembly
28 rotates in a counterclockwise direction indicated by arrow 11
in FIG. 3. As a result, rock material deposited on the Landing surface
39 is driven radially outwardly from the center of the table assembly
28 by centrifugal force. The guide surfaces 54 of the shoes 44 define
travel paths through which the rock material is directed. The guide
surfaces 54 direct the rock material toward the anvil ring 64 at
an angle which optimizes breakage. The broken rock material collects
at the bottom of the housing 12 where it is removed.
In accordance with certain aspects of the present invention, the
centrifugal force acting to throw the shoe radially outwardly is
resisted by the bracket 42 thereby reducing shear forces acting
on the mounting bolts 62. The openings 50 in the bracket 42 are
aligned with the threaded apertures 60 such that the contact surface
53 engages the support surface 47 as the table assembly 28 rotates.
In the currently preferred embodiment, the openings 50 are formed
as horizontally extending slots. The slots have radiused inside
and outside edges 80 81 formed about centerlines 82a and 82b, respectively.
Thus, the mounting bolts 62 extending through the slots, and the
shoe 44 to which the bolts 62 are attached, are allowed to slide
radially outward. Before the mounting bolts 62 contact the outside
edges 81 of the slots, the contact surface 53 of the shoe 44 engages
the support surface 47 of the bracket 42. As a result, the shear
forces on the mounting bolts 62 are significantly reduced since
the bracket structure 42 rather than the bolts 62 resists movement
of the shoe 44 in the radially outward direction.
In accordance with additional aspects of the present invention,
a liner 90 is attached to an outside face 92 (FIG. 6) of the bracket
42 to thereby protect the bracket 42 from rock material ricocheting
off of the anvil ring 64. The liner 90 has a substantially planar
rear mounting surface 91 and a curved front shielding surface 93
sized to substantially cover the outside face 92. As best illustrated
in FIGS. 6-8 a pair of bolt holes 94 extend through the liner 90
from the front surface 93 to the rear surface 91 and threaded apertures
95 are formed in the outside face 92 of the bracket, so that the
liner 90 may be releasably attached to the bracket 42 using bolts
(not shown).
Spacers 97 are located on the mounting surface 91 of the liner
90 generally disposed around the each bolt hole 94. The spacers
97 may be formed integrally with the liner 90 such as by machining
or casting, or may be provided as separate components which are
permanently affixed to the liner 90 such as by welding. In the
illustrated embodiment, the spacers 97 are annular washers welded
to the mounting surface 91 of the liner 90. The spacers 97 have
a thickness "T" (FIG. 8) which creates a gap 98 between
the outside face 92 of the bracket 42 and the mounting surface 91
of the liner 90 when the liner 90 is attached to the bracket 42.
As noted above, deflections are greatest near the top of the bracket
42 and therefore the gap 98 is most preferably formed between the
top portions of the liner 90 and bracket 42. In the illustrated
embodiment, the gap 98 is formed substantially uniformly between
the entire lengths of the liner 90 and bracket 42. Only the spacers
97 contact the bracket 42 and therefore the gap 98 allows the bracket
42 to deflect unevenly without creating a significant prying force
against the liner 90.
The vertical shaft impact crusher of the present invention has
significant advantages over prior crushers. By providing a shoe
assembly in which a contact surface of the shoe engages a support
surface of the bracket, the risk of shearing mounting bolts connecting
the shoe to the bracket is reduced. In addition, the use of spacers
on the mounting surface of a liner creates a gap between the liner
and the bracket, thereby reducing the risk of prying the liner from
the bracket due to uneven deflections in the bracket.
The foregoing detailed description has been given for clearness
for understanding only, and no unnecessary limitations should be
understood therefrom, as modifications would be obvious to those
skilled in the art. |