A Hammer mill, comprising discs (1) mounted on a drive shaft (2),
crosspieces (3) for spacing apart the discs (1), hammers (4) mounted
between the discs (1) at intervals defined by the crosspieces (3)
and spindles (5) for swingably mounting the hammers (4) and passing
through the discs (1). A device (6) is provided for selectively
individually locking the hammers (4) in a retracted position in
the drum which drives the hammers (4), for releasing the hammers
for outward swinging. The locking device is a fluid-actuated peg
(7) insertable in and withdrawable from a hole (9) in each hammer.
1. Hammer mill, comprising discs (1) mounted on a drive shaft (2),
crosspieces (3) spacing apart the discs (1), hammers (4) mounted
between the discs (1) at intervals defined by the crosspieces (3),
spindles (5) on which the hammers (4) are swingably mounted, said
spindles passing through the discs (1), and means (6) for selectively
individually locking the hammers (4) in a retracted position between
the discs or freeing the hammers for movement to an extended position.
2. Mill according to claim 1 wherein said means (6) for locking
the hammers (4) in a retracted position comprises pegs (7) retractably
disposed in the discs (1) by means of jacks (8) and each being receivable,
the hammers (4) being retracted between the discs (1), in a hole
(9) of corresponding shape provided in at least one lateral face
of the said hammers (4).
3. Mill according to claim 2 said holes (9) being spaced from
said spindles (5).
FIELD OF THE INVENTION
The present invention concerns the field of recovery of metals
from manufactured articles, particularly by milling with hammer
mills, and has as an object a hammer mill provided with a device
for locking the hammers in a retracted position in the drum.
BACKGROUND OF THE INVENTION
Recovery of metals from worn-out articles, particularly automotive
vehicles, by means of crushers or grinders, is generally effected
by introducing the articles into a hammer mill which tears and cuts
up the material entering into the said mill, by interaction with
one or several anvils, and which ejects and/or evacuates through
sifting walls the resulting mechanical chips having a predetermined
In known mills, the hammers are generally mounted on a rotor constituted
by an assembly of discs separated by crosspieces at the level of
the fixation of the hammers which are eclipsable in the rotor and
which turn freely about their axis of fixation. During operation,
these hammers are subjected to wear and must accordingly be mounted
in an invertible manner on their spindle, so as to prolong their
useful life. To prevent such an inversion of the mounting, it has
also been proposed to drive the rotor in a reversible manner.
Finally, depending on the materials to be milled, a greater or
lesser number of hammers must be operated which consequently requires,
upon each change of the material to be milled, an intervention on
the rotor so as to mount or dismount a certain number of the hammers.
Such interventions, however, present the disadvantage of relatively
long down time of the machine, which considerably increases maintenance
OBJECTS OF THE INVENTION
The present invention has as an object to overcome these disadvantages.
Specifically, it has as an object a hammer mill characterized in
that it is provided with a device for locking the hammers in a retracted
position in the drum which drives the hammers.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be better understood from the following description,
which refers to a preferred embodiment, given by way of non-limiting
example and explained with reference to the accompanying schematic
drawing, in which:
FIG. 1 is a partial view in side elevation and in section of a
hammer drum according to the invention, and
FIG. 2 is a view in front elevation of the drum according to FIG.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention and as is shown more particularly in
FIGS. 1 and 2 of the accompanying drawing, the hammer mill, which
comprises a drum for driving the hammers, essentially constituted
by discs 1 mounted on a drive shaft 2 by crosspieces 3 for spacing
apart the discs 1 by hammers 4 mounted between the discs at intervals
defined by the crosspieces 3 and by pinions 5 connecting the hammers
4 traversing the discs 1 is characterized in that it is provided
with a device 6 for locking the hammers in a retracted position
in the drum which drives the hammers.
The device 6 for locking the hammers 4 in a retracted position
in the drum is advantageously constituted by pegs 7 retractably
disposed in the discs 1 by means of jacks 8 and each cooperating
in service position, the hammers 4 being retracted between the discs
1 with a hole 9 of corresponding shape provided in at least one
lateral face of the said hammers 4.
According to a characteristic of the invention, each hammer 4 is
provided on at least one lateral face with at least one specific
hole 9 passing all the way through or being blind, preferably conical
or conical beginning at each face, each hole 9 being intended to
cooperate with a corresponding peg 7 actuated by at least one jack
8 and being disposed offset from the hole which accommodates its
articulation pinion 5.
The fluid supply conduits for controlling the jacks 8 are advantageously
bored in the discs 1 and in the crosspieces 3 and are connected
to an end panel connected to a central distribution unit through
the intermediary of valves. Such an end panel and corresponding
distribution valves are known in the art, and are not described
According to a characteristic of the invention, the control jacks
8 for the pegs 7 are auto-locking jacks and are actuated by diametrally
opposed pairs of jacks, a manometric contact (not shown) being provided
for each jack 8 and detecting the arrival at the end of its course
of penetration of the pegs 7 in the corresponding holes 9 of the
hammers 4. Thus, a perfectly correct and imbalance-free operation
is continuously assured.
Thanks to the invention, it is possible to provide a device permitting
selective retraction or selective liberation of the hammers of a
hammer mill as a function of the products to be milled. In addition,
thanks to this embodiment, the drum for driving the hammers may
be provided with a maximum of hammers, certain of which could be
freed, for example, after wearing of the drums in service and always
such that the drum rotates without imbalance.
The device according to the invention is particularly advantageous
in the case where a reversible drum is used, because it permits
increasing the autonomous operation of this drum by preventing a
significant number of changings of the drums or remounting of the
It will be understood that the invention is not limited to the
embodiment described and shown in the accompanying drawing. Modifications
remain possible, especially from the point of view of the constitution
of the various elements or by substitution of equivalent techniques,
without departing whatsoever from the scope of protection of the