Abstrict A To facilitate manipulation of an impact member 20 of a coarse
reduction impact crusher, the impact member 20 together with its
wedge members 22 is only loosely inserted in an accommodating cavity
14 for the impact member, whereby when rotation of a rotor 10 is
started the impact member 20 and wedge members 22 are urged by the
resulting centrifugal force from a disengaged position near the
axis of the rotor into a wedged position relatively distant from
said axis.
Claims I claim:
1. A coarse reduction impact crusher comprising a rotor containing
a plurality of impact members which are fixable in respective accommodating
cavities in the rotor; one of said accommodating cavities comprising
a radially outwardly facing opening and being at least in part narrowed
by an abutment beam which extends tangentially over said one accommodating
cavity, each impact member in use being fixed in its respective
cavity by at least one wedge member, such that at least one impact
member is slidably disposed within each accommodating cavity along
with at least one wedge member moveable under the influence of centrifugal
force resulting from rotation of the rotor in a direction at least
approximately radial, whereby at least one wedge member moves from
a disengaged position close to the rotational axis of the rotor,
to a wedged position distant from the rotational axis, and wherein
a distance of the center of inertia of said impact member from the
rotational axis is greater than a distance of the center of inertia
of said wedge member from the rotational axis; said wedge member
having a wedge inclination region which contacts the impact member
in use to prevent jamming of said wedge member.
2. The coarse reduction impact crusher of claim 1 wherein one impact
member and one wedge member are disposed within said one accommodating
cavity.
3. The coarse reduction impact crusher of claim 1 further comprising
a limiting plate releasably fixed to the rotor and extending over
said radially outwardly facing opening of said accommodating cavity.
4. The coarse reduction impact crusher of claim 3 wherein said
abutment beam is located on one side of said radially outwardly
facing opening of said accommodating cavity and said releasably
fixed limiting plate is located on the other side of said outwardly
facing opening such that said wedge member is disposed below said
limiting plate.
5. The coarse reduction impact crusher of claim 1 wherein said
impact member is provided with a breaking loci such that when said
impact member is over stressed, breakage of said member occurs at
said loci.
6. The coarse reduction impact crusher of claim 1 wherein said
impact member comprises two thrust members symmetrically disposed
on the radially disposed surface of said impact member.
7. The coarse reduction impact crusher of claim 6 wherein said
thrust members extend along the radially disposed surfaces of the
impact member.
8. A coarse reduction impact crusher comprising a rotor containing
a plurality of impact members which are fixable in respective accommodating
cavities in the rotor; each impact member in use being fixed in
its respective cavity by at least one wedge member, such that at
least one impact member is slidably disposed within each accommodating
cavity along with at least one wedge member moveable under the influence
of centrifugal force resulting from rotation of the rotor, whereby
at least one wedge member moves from a disengaged position close
to the rotational axis of the rotor, to a wedged position distant
from the rotational axis and wherein each accommodating cavity comprises
a radially outwardly facing opening being at least in part narrowed
by an abutment beam which extends tangentially over said accommodating
cavity such that when said impact member and said wedge member are
in the wedged position, said abutment beam is engaged on its lower
side by a thrust member affixed to said impact member.
9. The coarse reduction impact crusher of claim 8 wherein said
impact member and said wedge member move in a direction at least
approximately radial.
10. The coarse reduction impact crusher of claim 8 wherein a distance
of the center of inertia of said impact member from the rotational
axis is greater than a distance of the center of inertia of said
wedge member from the rotational axis.
11. The coarse reduction impact crusher of claim 8 wherein said
wedge member further comprises a wedge inclination region which
contacts said impact member in use to prevent jamming of the impact
member.
Description This invention relates to a coarse reduction impact crusher having
a rotor which bears the impact members, which impact members are
fixed in recesses in the rotor by means of wedge members (hereinafter
also to be referred to as "wedges").
BACKGROUND OF THE INVENTION
Coarse reduction impact crushers are employed for breaking rock.
A rotor is disposed in the housing of the crusher, which rotor has
a preferred operating direction but can be reversed.
The crushing tools employed in the crusher comprise a plurality
of impact members. These tools are subject to wear, and therefore
are replaceably fixed to the rotor, namely they are fixed in suitable
accommodation cavities in the rotor by means of wedges. The wedges
are driven into a fixed wedged position by mechanical impact means
or hydraulic means. Because the tools (impact members) are subject
to wear, they are symmetrically configured, so that when one impact
edge experiences excessive wear one need only rotate the impact
member in its accommodation cavity and re-fix it, to take advantage
of a second, fresh impact edge.
Known means of fixing impact members have certain drawbacks, e.g.,
when mechanical wedge means are used, dust and fine particles tend
to cause the impact members to become jammed, so that they can be
rotated or replaced only with difficulty and corresponding expense.
Hydraulic fixing systems are costly, because for control purposes
the hydraulic lines must be extended to the exterior from the rotating
rotor.
The underlying problem of the invention is to refine the known
system wherein the impact members are mechanically fixed in their
respective accommodating cavities by means of wedges, such that
(in the refinement) the wedged configurations or wedges are easily
and readily releasable, or may even release themselves when the
rotor is stopped.
SUMMARY OF THE INVENTION
According to the invention the impact members and their respective
wedges (one or more wedges per impact member) are slidably disposed
in a plurality of respective accommodating cavities in the rotor,
whereby a cavity serves to accommodate a respective impact member
(or members), and wherein the impact members and wedge members can
move under the influence of centrifugal force, such movement being
between a released position relatively close to the rotational axis
and a wedged position relatively distant from the rotational axis.
It will be appreciated that with this solution each impact member
and its corresponding wedge(s) are readily installed in the respective
accommodating cavity, obviously at a time when the rotor is stopped.
In this rest position (also in the nature of a disengaged position),
with the rotor stopped, no mechanical operations and no hydraulic
means need be provided in order to achieve fixing of the impact
members. Rather, after the impact members have been installed in
the disengaged position on the rotor, one need only start rotation
of the rotor. The resulting centrifugal forces will then cause the
impact members and wedge(s) to move from their originally assumed
disengaged positions and into positions more distant from the axis,
in which latter positions fixation by wedging will occur. For this
it is sufficient for the two parts and/or the wall(s) of the accommodating
cavity to undergo corresponding "ausforming" deformation.
If it is necessary or desirable to stop the rotor, due to wear
or for other reasons, the centrifugal force which has supplied the
wedging force of course disappears. Accordingly, the parts separate
from each other and again lie loose in the accommodation cavity.
It is evident that the direction of shifting of the parts between
the disengaged position and the wedged position should be at least
approximately radial.
In a preferred embodiment of the present invention means are provided
whereby, when the rotor begins rotation, first the impact member
is moved to its wedging position and then the wedge is moved to
its wedging position. That is, the wedge moves thusly only after
a slight delay. This can be achieved by providing that the distance
of the center of inertia of the impact member from the rotational
axis is greater than the distance of the center of inertia of the
associated wedge from the rotational axis. In this way, when the
rotor is started in rotation, the centrifugal force needed to move
the impact member from the disengaged position to the wedging position
is reached sooner than the corresponding force for the associated
wedge member. Accordingly, the wedge member will not move against
and fixingly wedge the impact member until the impact member has
essentially reached its operating position under the action of the
centrifugal force.
Upon stopping of the rotor, one can facilitate the loosening of
the parts which have become wedged together in the wedged position
if the region of the wedge which lies against the impact member
is provided with a wedge inclination such that the impact member
does not become jammed under the operating conditions experienced.
One can achieve conditions of movement for the wedging and re-loosening
of the impact member, depending on the angular velocity of rotation
of the rotor, which conditions are easy to manage, if only one impact
member and one wedge member, and not more, are disposed in a given
accommodating cavity. However, it is also possible to apply the
same principle (i.e., the principle which underlies the invention)
to an arrangement comprising a total of more than two impact members
and wedge members, particularly if suitable guide means are provided
for said members. Moreover, it is possible to operate with unequal
numbers of impact members and wedge members; e.g., for one impact
member to be wedged by a plurality of wedge members. The free mobility
has a beneficial influence on the effective forces and thereby on
the course of the movements.
In a further preferred aspect of the present invention, the cavity
for accommodating the impact member has a large opening on the peripheral
surface of the rotor, so that the wedge member and particularly
the impact member can be readily inserted. However, means should
be provided so that this opening which is chosen to be large in
order to facilitate manipulation can be reduced in size so that
the impact member and wedge member are not driven out of the accommodating
cavity under the influence of the centrifugal forces but only come
to be supported against each other and the boundaries of said cavity.
Accordingly, in a preferred embodiment of the invention, pieces
are provided for the purpose of reducing the opening size which
extend approximately in the tangential direction (i.e., normal to
the radius of and in a plane of rotation of the rotor), over the
radially outer opening of the cavity for accommodating the impact
member. One of said pieces, namely an abutment beam for the impact
member, is fixed to the rotor, has an inclined surface which provides
a positioning means for the impact member, and extends out over
the radially outer opening of the accommodating cavity such that
said beam can be engaged on its underside in said extended region
by a thrust member projecting outward from the impact member. When
rotation of the rotor commences, the impact member is then urged
radially outward from its loose position, such that said thrust
member comes to rest against the underside of the abutment beam,
while at the same time the impact member comes to be supported against
the corresponding wedging surface of the abutment beam. In this
way, means are provided to correctly position the impact member
prior to its being wedged by the wedge member.
In another preferred embodiment of the present invention, a limiting
plate is releasably fixed to the rotor (e.g., by screws) on the
opposite side of the radially outer opening of the cavity for accommodating
the impact member, which side is namely the side opposite to that
of the abutment beam. The limiting plate overlaps the impact member
in a region of the accommodating cavity, providing fixing means
and at the same time providing additional means of closing off the
accommodating cavity.
With this particular arrangement, it may also be advantageous to
provide the impact member with breakage loci in the form of bores,
affording a kind of overload protection, whereby when a reaction
force exerted by a foreign body in the crushing space is transmitted
to the impact member, the impact member will break at the breakage
loci and will disintegrate into small pieces which are relatively
easy to extract from the coarse reduction impact crusher. With this
type of protection, collateral damage is also minimized.
Additional details, advantages, and features of the invention will
be apparent from the following description with reference to FIG.
1. For the purposes of disclosure of matter essential to the invention,
all details and features of the Figure not expressly described hereinbelow
are incorporated herein by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a partial end view, in partial cross section, of the
rotor of a coarse reduction impact crusher the axis of which is
perpendicular to the plane of the paper.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to FIG. 1 rotor 10 of a coarse reduction impact
crusher revolves around an axis of rotation 12. The rotor can be
stopped and can be rotated in both rotational directions. Four accommodation
cavities 14 for accommodating impact members are formed on the outer
periphery of the rotor 10; these are disposed at a mutual angular
separation of about 90.degree.. Each accommodation cavity 14 has
a radially outer opening 16 through which it communicates with the
exterior at the periphery of the rotor 10. The radially inner base
of each opening 16 has a stepped configuration. Beneath an abutment
beam 18 a relatively deep recess zone is provided for loose insertion
of the impact member 20. Next to said recess zone, the base has
a support structure for an associated wedge 22 when said wedge is
in the "rest" position, which support structure is somewhat
farther from the axis than the recess zone part of the cavity 14
which accommodates the impact member 20.
The impact members 20 preferably have a symmetric shape, which
is known (see FIG. 1). The symmetry enables reversing the members
20 by mere rotation into any of four positions, depending on the
conditions of use and on the wear experienced. Replacement is necessary
only after complete wear, which is approximately four-fold. Obviously,
appropriate known and customary measures may be employed (not shown
in the exemplary embodiment illustrated in FIG. 1) to extend service
life by stepwise advancing of the impact member occasionally, as
wear proceeds during service.
A critical feature here is that the impact member 20 can be installed
and emplaced loosely through the outer opening 16 and into the deep
recess of the bottom of the corresponding accommodating cavity 14.
At this location, i.e., at the outer opening 16 the abutment beam
18 extends out over the cavity for accommodating the impact member,
said extension being in approximately the rotationally tangential
direction. An inclined surface at the head of the abutment beam
18 serves to support and position the impact member 20. In addition,
the impact member has two thrust-type supporting members 24 (also
symmetrically disposed) which extend along the radially disposed
surfaces of the impact member 20. In the wedged position illustrated
in FIG. 1 one of these thrust supporting members 24 seen in operation,
extends under the head of the abutment beam 18 thereby limiting
the radial movement of the impact member 20 when said member is
under the influence of centrifugal force.
On the opposite side of the outer opening 16 a limiting plate 26
extends over said opening. Plate 26 is releasably fixed to the outer
periphery of the rotor and is disposed nearly or approximately tangentially
thereto. The limiting plate 26 may be attached to the rotor by a
non-removeable screw 28 or the like. Advantageously, plate 26 is
associated with a guideway on the rotor, so that when the screw
28 is loosened the plate and the screw 28 can be easily slide in
and out between a retracted position in which the plate does not
extend over the opening 16 and the position illustrated in FIG.
1. To provide freedom of movement for the screw 28 the limiting
plate 26 is provided with a suitable longitudinal slot 30 which
can be seen in the left upper part of FIG. 1. In addition, the limiting
plate 26 has a recess 32 on its upper side, to accommodate the thrust
supporting member 24 which is not currently in use.
Accordingly, with the parts positioned as in the arrangement illustrated
in FIG. 1 there is maximal outward closure of the cavity 14 for
accommodating the impact member 20 with respect to the periphery
of the rotor. Thus, said cavity is exposed to only minimal soiling
hazard.
For installation of the impact member, the limiting plate 26 is
retracted to free the radially outer opening 16 of the accommodating
cavity 14 for the impact member 20. Then the wedge 22 is loosely
inserted into the side of the accommodating cavity 14 which is not
overlapped by the abutment beam 18 following which the impact member
20 is also loosely inserted into the accommodating cavity 14. Next,
the limiting plate 26 is shifted again into its position shown in
FIG. 1 and is fixed with the aid of the screw 28. In this position
one already has the impact member 20 loosely pre-positioned. However,
said member is not yet wedged.
If the machine is now started, the impact member 20 will be urged
radially outward such that one of its supporting thrust members
24 comes to abut upward against the lower side of the abutment beam
18. The center of inertia of the wedge 22 is closer to the rotational
axis 12 and therefore the wedge experiences less centrifugal force
per unit mass. Shortly after the termination of the outward movement
of member 20 the wedge 22 completes movement from its rest position
where it is in a disengaged state, radially outwardly to its wedged
position. During this movement of the wedge 22 its nearly radially
oriented rear side is urged against the also nearly radially oriented
side wall of the cavity 14 for accommodating the impact member 20
and the inclined wedge surface of the wedge 22 travels along the
impact member 20 wherein eventually the impact member 20 becomes
fixedly wedged in the rotor. The inclination angle of the wedge
22 is chosen such that jamming of the wedge 22 does not occur. Accordingly,
when the rotation of the rotor 10 is later stopped the wedge 22
can be loosened (or will loosen itself) without problems.
The invention ensures that the impact member 20 can be positioned
and wedged without the difficulties presented by soiling. The proper
wedging of the impact member reliably counters the tendency for
the impact member 20 to shift or tilt when the coarse reduction
impact crusher is in operation. After the rotor is stopped, this
secure fixing of the impact member 20 is released or readily releasable
on account of the disappearance of the centrifugal force when the
rotor is stopped, which force had held the parts together. |