Machine tools abstract
A self-feeding shredding device, particularly for liquid lubricant/refrigerant
filtration plant for machine tools with swarf removal, incorporating
a channel element in which a motorized screw conveyor sits, having
one end of reduced diameter that passes through an internally grooved
cylindrical body. A lobe rotor is axially faced up against the outside
of the grooved cylindrical body and its rotation controlled by the
screw conveyor. The swarf, unwound and stretched out from the reduced
diameter end tip of the screw conveyor along the grooved cylindrical
body, is pushed towards the lobe rotor and shredded.
Machine tools claims
What is claimed is:
1. A self-feeding shredding device for machine tools with swarf
removal, including a conveyor incorporating a channel for feeding
lubricant/refrigerant liquids and in which a motorised screw is
positioned, said screw having an end tip which constitutes a drive
member for a shredding group including an internally-grooved cylindrical
body arranged coaxially with respect to said end tip of said screw
and a lobe rotor connected to said end tip of said screw and axially
disposed against an outside end of said grooved cylindrical body
and rotationally driven by said screw.
2. A shredding device according to claim 1 wherein said end tip
of said screw has a smaller diameter than the rest of the said screw
conveyor.
3. A shredding device according to claim 1 wherein said end tip
of said screw has an end tang that stands proud of said grooved
cylindrical body and on which said lobe rotor is coupled for rotation.
4. A shredding device according to claim 3 wherein said lobe rotor
is inserted inside a bottom ring frontally fixed to said grooved
cylindrical body.
5. A shredding device according to claim 1 wherein said lobe rotor
is equipped with a number of lobes ranging from 2 to n.
6. A shredding device according to claim 1 wherein said channel
element is equipped with bottom openings.
7. A shredding device according to claim 1 wherein said screw
has an initial end functionally connected to a drive group equipped
with an automatic counter-rotation device.
8. A shredding device according to claim 1 wherein said cylindrical
body has axially-arranged grooves.
9. A shredding device according to claim 1 wherein said cylindrical
body has grooves angled with respect to an axis thereof.
10. A shredding device according to claim 1 wherein said end tip
of said screw is radially floating with respect to said grooved
cylindrical body.
Machine tools description
BACKGROUND OF THE INVENTION
The present invention refers in general to machine tools with swarf
or chip removal.
Traditionally, in industrial plants that use such machine tools,
the relative lubricant/refrigerant liquids and machining swarf are
transported, generally via inclined floor-level channels, to filtration
plants that separate the solid parts from the liquids so that the
latter can be reutilised.
This solution involves evident complications due to the layout
of the channels, as well as the space occupied by the channelling
and flexibility problems in relation to the positioning of the machine
tools.
SUMMARY OF THE INVENTION
Hence, it would be auspicious to eliminate these channels and connect
the lubricant/refrigerant liquid discharges from the machine tools
with the filtration plant via a network of overhead pipes, which
is less complicated, less space-consuming and much more flexible
when setting up. Nevertheless, this requirement does not reconcile
with the presence of long metal swarf in the lubricant/refrigerant
liquids. Such swarf is normally of variable length and even several
centimeters long, and therefore cannot be transferred to the filtration
plant connection piping using normal hydraulic pumps.
The object of this invention is that of solving this problem and
to reduce the swarf length so as to enable the pumping of lubricant/refrigerant
liquids containing swarf using normal hydraulic pumps.
According to the invention, this objective is achieved by a self-feeding
shredder, characterized by the fact that it consists of a conveyor
including a channel element for feeding the lubricant/refrigerant
liquids in which a motorized screw conveyor sits, the end tip of
which constitutes the advancement member of a shredding group, including
an internally grooved cylindrical body arranged coaxially to the
said end tip of the screw conveyor and a lobe rotor axially faced
against the outside of the said grooved cylindrical body and controlled
in rotation by the said screw conveyor.
The combined effect of the rotation of the screw and the presence
of the grooves inside the cylindrical body of the shredding group
creates an effective unwinding, straightening and stretching action
on the elongated particles of metal swarf as they are self-fed to
the rotor. The interaction between the lobes of the rotor and the
extremity of the grooved cylindrical body faced against it produces
a grinding and shredding action, reducing the size and length of
the metal swarf particles to levels at which they can be pumped,
together with the lubricant/refrigerant liquids, to the filtration
plant.
The same advantageous functional result is achieved even in the
case the shredding device according to the invention is employed
for the mere disposal of the swarf produced by the machine tools,
i.e. independently of the presence of a lubricant/refrigerant filtration
plant, i.e. independently of the presence of a lubricant/refrigerant
filtration plant, and/or of distribution and/or conveying systems
for the lubricant/refrigerant liquids and swarf (e.g. even in the
case the swarf are removed by means of collecting containers).
In order to render the unwinding and stretching effect on the elongated
swarf more efficient, the aforesaid end tip of the screw conveyor
has a diameter that is opportunely smaller than that of the rest
of the aforesaid screw. This end tip is equipped with an opportune
end tang that stands proud of the aforesaid cylindrical body and
on which the lobe rotor is engaged for rotation.
Another characteristic advantage of this invention is that the
motorised group driving the screw conveyor is equipped with a counter-rotation
device, which is set up to automatically intervene during normal
running in cases where rotation of the screw slows down or stops
due to swarf clogging or blockages.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in detail with reference to
the attached drawings, which are supplied purely as a non limitative
example, wherein:
FIG. 1 is a schematic perspective of a self-feeding shredding device
according to the present invention,
FIG. 2 is a longitudinal, side-section view of FIG. 1
FIG. 3 is an exploded view of FIG. 1
FIG. 4 is a larger-scale front view of a first example of lobe
rotor actuation on the shredding device, and
FIG. 5 is a similar view of a second type of lobe rotor actuation.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, the self-feeding shredding
device, as exemplified in the drawings, includes a support frame,
generically indicated as item 1 arranged for mounting in correspondence
with the lubricant/refrigerant liquids outlet of a machine tool
or group of machine tools with swarf removal.
The lower part of the support frame (1) carries a horizontal channel
element (2), the bed of which has a series of slots (3) and in which
a motorised screw conveyor (4) sits.
In the example shown, the screw conveyor (4) incorporates a long
tubular element (5) with the blade (6) of the screw mounted on its
external surface and coupled at one end to a shaft (7). The shaft
(7) is mounted on the frame (1) using, for example, roller bearing
supports (not shown) to allow rotation and is connected to a motorised
drive group. In the case of the example shown, this group is comprised
of an electric motor and a chain drive indicated schematically as
9.
A counter-rotation device is opportunely coupled with the motorised
drive group. This counter-rotation device might incorporate a sensor
for the angular speed of the shaft (7) or an absorption sensor for
supply current to the motor (8), suitable for automatically controlling--for
motives explained in the following--the halting and rotation of
the screw conveyor (4) in the opposite direction to that of normal
running for a predetermined number of revolutions.
The height of the screw blade (6) is reduced in correspondence
with the end tip (10) of the screw conveyor (4). This tip (10) passes
coaxially through a cylindrical sleeve (11) having on its inner
circumference a series of grooves (17), which may be oriented axially
or with an angle relative to the axis of the sleeve (11), and is
fixed at one end, via a flange (12), to a vertical support plate
(13) that is, in turn, rigidly fixed to the channel element (2).
The other end of the grooved cylindrical sleeve (11) has another
flange (14) onto which a bottom ring (15) is fixed.
An axial tang (16) coupled in rotation within the end tip (10)
of the screw conveyor (4) has a prismatic tip (18) onto which a
lobe rotor (19) is keyed.
This rotor (19), which axially faces the external end of the grooved
cylindrical body (11), can have from 2 to n lobes: FIGS. 4 and 5
show two examples of alternative implementations in which the rotor
has respectively six and four lobes, or radial arms. In operation,
the lubricant/refrigerant liquid and small-size swarf are discharged
under gravity from the bed of the channel element (2), via the relative
slots (3), to a collection tank for pumping to the filtration plant.
Longer particles or accumulations of swarf are transferred by the
screw conveyor (4) in the direction of its end tip (10). Due to
the reduced height of the screw blade (6) and the presence of the
grooved cylindrical body (11), the swarf is subjected to an unwinding
and stretching action in this end tip zone (10), whilst being simultaneously
advanced in the direction of the rotor (19). Due to the effect produced
by the interaction between the edges of the lobes of the rotor (19)
and the end of the cylindrical body (11) facing them, the swarf
is subjected to a grinding and shredding action.
Following this grinding and shredding action the swarf, which leaves
the device via the bottom ring (19), reaches the collection tank
where it is pumped with the lubricant/refrigerant liquid to the
filtration plant. In cases where swarf amasses and clogs in the
end tip (10) zone to the extent that it causes the rotation of the
screw conveyor (4) to slow down or even stop, the previously described
counter-rotation device will automatically rotate the said screw
conveyor (4) in the opposite direction for a brief period of time
to restore normal operating conditions. Nevertheless, it is necessary
to underline that the risk of swarf blockage is reduced by the fact
that the end tip (10) of the screw conveyor (4) is not supported,
but is free to float radially with respect to the grooved cylindrical
body (11).
Naturally, it is understood that the constructional details and
the forms of realization could be extensively changed with respect
to that described and illustrated without leaving the scope of this
invention, as defined in the following claims. Thus, as already
pointed out in the above, the shredding device according to the
invention can also be advantageously employed for the mere disposal
of the swarf produced by the machine tools, i.e. even in the absence
of lubricant/refrigerant filtration plants, i.e. independently of
the presence of a lubricant/refrigerant filtration plant, and/or
of distribution and/or conveying systems for the lubricant/refrigerant
liquids and swarf (e.g. even in the case the swarf are removed by
means of collecting containers). |