Note: Descriptions are shown in the official language in which they were submitted.
CA 02710589 2011-04-19
AN ABRASIVE DISC FOR A MULTIPLE DISC GRINDING MACHINE, AND A
GRINDING MACHINE INCLUDING SAID DISC
TECHNICAL FIELD
The present application relates generally to abrasive discs, such as those
used in a multiple disc grinding machine, and to a grinding machine having
such discs which may be used, for example only, for processing stone and like
materials.
BACKGROUND
Grinding machines having multiple abrasive discs are used in a number
of applications, such as in particular for the purpose of processing stone and
like materials. Such grinding machines use a plurality of rotating cutting
and/or grinding discs which have abrasive elements. Such a plurality of
grinding discs may be combined into a pack on a shaft which may be caused to
rotate. When using multiple disc grinding machines of the above-mentioned
type, use is typically made of coolant fluids which are conveyed to the
processing zones to ensure that the heat generated by such processing (ex:
cutting and/or grinding), following contact between the abrasive elements and
the surfaces of the workpiece, is adequately dissipated. In known solutions
the
shaft is provided with an internal hole in order to convey the fluid to a
distributor member, for instance a bushing interposed between the shaft and
the discs and designed to collect the fluid and distribute it to the exterior
of the
discs in the processing zones. This solution nevertheless requires the
provision
of a specific distributor member which has to be mounted when the cutting
discs are being mounted on the multiple disc grinding machine.
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SUMMARY OF THE INVENTION
A main object of the invention is to provide an abrasive disc for multiple
disc grinding machines designed to provide a coolant distribution system which
is structurally simpler and easier to use, but which continues to provide
efficient
cooling of the tool.
This object is achieved by the present invention, in accordance with one
aspect of which there is provided an abrasive disc for a multiple disc
grinding
machine, the abrasive disc comprising: a disc-shaped support having a
circumferential rim on which an abrasive material is placed and an opposing
central hole for fitting on to a driving shaft of the grinding machine, said
hole
extending through the thickness of the disc-shaped support; and wherein a
portion of said central hole has a diameter greater than the diameter of the
connection to said shaft, such that an annular chamber is formed in the
thickness of the support; and comprising at least one radial recess formed on
a
front surface of the disc-shaped support and extending from said annular
chamber towards the circumferential rim of said disc, in such a way that a
coolant fluid fed into the driving shaft can accumulate in said annular
chamber
and can then flow through said radial recess towards the abrasive edge of said
disc.
There is also provided, in accordance with another aspect of the present
invention, a multiple disc grinding machine comprising a driving shaft
receiving
thereon a plurality of abrasive discs combined in a pack on said shaft, each
of
said discs comprising a disc-shaped support having a circumferential rim on
which an abrasive material is placed and an opposing central hole for fitting
on
to a driving shaft of the grinding machine, said hole extending through the
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thickness of the disc-shaped support; and wherein a portion of said central
hole has a diameter greater than the diameter of the connection to said shaft,
such that an annular chamber is formed in the thickness of the support; and
comprising at least one radial recess formed on a front surface of the disc-
shaped support and extending from said annular chamber towards the
circumferential rim of said disc, in such a way that a coolant fluid fed into
the
driving shaft can accumulate in said annular chamber and can then flow
through said radial recess towards the abrasive edge of said disc.
There is further provided, in accordance with another aspect of the
present invention, a multiple disc grinding machine comprising: a driving
shaft;
a plurality of abrasive discs combined in a pack on said shaft, each of said
discs
comprising a disc-shaped support having a circumferential rim on which an
abrasive material is placed and an opposing central hole for fitting on to a
driving shaft of the grinding machine, said hole extending through the
thickness
of the disc-shaped support; and wherein a portion of said central hole has a
diameter greater than the diameter of the connection to said shaft, such that
an annular chamber is formed in the thickness of the support, and wherein at
least one radial recess is formed on a front surface of the disc-shaped
support
and extends from said annular chamber towards the circumferential rim of said
disc, in such a way that a coolant fluid fed into the driving shaft can
accumulate
in said annular chamber and can then flow through said radial recess towards
the abrasive edge of said disc; and wherein the driving shaft includes at
least
one hole for feeding coolant fluid, the hole extending radially in the end
portion
of said shaft which is intended to receive the plurality of cutting discs, and
opening on a cylindrical shell which comes into contact with the discs, in
which
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the transverse thickness of the discs is smaller than the diameter of said at
least one hole for the feed of coolant fluid in the shaft, so as to permit the
passage of fluid from said feed hole to the annular chamber of the
corresponding disc and thence to the corresponding recess.
There is further still provided, in accordance with another aspect of the
present invention, a multiple disc grinding machine comprising: a driving
shaft;
a plurality of abrasive discs combined in a pack on said shaft, each of said
discs
comprising a disc-shaped support having a circumferential rim on which an
abrasive material is placed and an opposing central hole for fitting on to a
driving shaft of the grinding machine, said hole extending through the
thickness
of the disc-shaped support; and wherein a portion of said central hole has a
diameter greater than the diameter of the connection to said shaft, such that
an annular chamber is formed in the thickness of the support, and wherein at
least one radial recess is formed on a front surface of the disc-shaped
support
and extends from said annular chamber towards the circumferential rim of said
disc, in such a way that a coolant fluid fed into the driving shaft can
accumulate
in said annular chamber and can then flow through said radial recess towards
the abrasive edge of said disc; and wherein the driving shaft includes at
least
one channel extending axially in the cylindrical shell of the end of the
driving
shaft intended to be connected to said discs, said channel communicating with
said radial hole for the feed of the coolant fluid and being capable of
bringing
said hole into communication with the annular chambers of the corresponding
discs which are fixed in a pack on the driving shaft.
There is further still provided, in accordance with another aspect of the
present invention, an abrasive disc for a multiple disc grinding machine, the
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abrasive disc comprising: a disc-shaped support having a circumferential rim
on
which an abrasive material is disposed to form an abrasive outer edge of the
abrasive disc and a central hole for fitting on to a driving shaft of the
grinding
machine, said hole extending through an axial thickness of the disc-shaped
support; and wherein a portion of said central hole has a diameter greater
than
the diameter of the shaft to which the abrasive disc is adapted to be
connected,
such that an annular chamber is formed in the thickness of the support; at
least a front surface of the disc-shaped supporting having at least one radial
recess formed therein, the at least one radial recess radially extending from
said annular chamber towards the circumferential rim of said disc, in such a
way that a coolant fluid fed into the driving shaft can accumulate in said
annular chamber of the disc-shaped support and can then flow through said
radial recess towards the abrasive outer edge of said abrasive disc; and
wherein the front surface of the disc-shaped support includes at least one
axially projecting portion which defines the axial thickness of the disc-
shaped
support and extends a radial distance away from the hole, the at least one
axially projecting portion having an axially-facing abutment surface thereon,
the abutment surface being adapted to abut a next adjacent disc when a
plurality of said abrasive discs are combined in a pack, the abutment surface
forming a friction member which prevents relative circumferential sliding of
said
abrasive disc relative to said next adjacent disc.
There is further still provided, in accordance with another aspect of the
present invention, a multiple disc grinding machine comprising: a driving
shaft;
a plurality of abrasive discs combined in a pack on said shaft, each of said
discs
comprising a disc-shaped support having a circumferential rim on which an
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abrasive material is placed and an opposing central hole for fitting on to a
driving shaft of the grinding machine, said hole extending through the
thickness
of the disc-shaped support; and wherein a portion of said central hole has a
diameter greater than the diameter of the connection to said shaft, such that
an annular chamber is formed in the thickness of the support, and wherein at
least one radial recess is formed on a front surface of the disc-shaped
support
and extends from said annular chamber towards the circumferential rim of said
disc, in such a way that a coolant fluid fed into the driving shaft can
accumulate
in said annular chamber and can then flow through said radial recess towards
the abrasive edge of said disc; and wherein the driving shaft includes at
least
one hole for feeding coolant fluid, the hole extending radially in the end
portion
of said shaft which is intended to receive the plurality of cutting discs, and
opening on a cylindrical shell which comes into contact with the discs, in
which
the transverse thickness of the discs is smaller than the diameter of said at
least one hole for the feed of coolant fluid in the shaft, so as to permit the
passage of fluid from said feed hole to the annular chamber of the
corresponding disc and thence to the corresponding recess.
There is further still provided, in accordance with another aspect of the
present invention, a multiple disc grinding machine comprising: a driving
shaft;
a plurality of abrasive discs combined in a pack on said shaft, each of said
discs
comprising a disc-shaped support having a circumferential rim on which an
abrasive material is placed and an opposing central hole for fitting on to a
driving shaft of the grinding machine, said central hole extending through the
thickness of the disc-shaped support; wherein a portion of said central hole
has a diameter greater than the diameter of the connection to said shaft, such
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,
that an annular chamber is formed in the thickness of the support, and wherein
at least one radial recess is formed on a front surface of the disc-shaped
support and extends from said annular chamber towards the circumferential
rim of said disc, in such a way that a coolant fluid fed into the driving
shaft can
accumulate in said annular chamber and can then flow through said radial
recess towards the abrasive edge of said disc; and wherein a surface of each
of
said abrasive discs in said pack abuts against a corresponding surface of the
adjacent abrasive disc, and wherein axial clamping action of the pack of the
abrasive discs causes said surfaces to act as friction members which prevent
relative sliding of adjacent ones of the abrasive discs; and wherein the
driving
shaft includes at least one channel extending axially in the cylindrical shell
of
the end of the driving shaft intended to be connected to said discs, said
channel
communicating with said central hole for the feed of the coolant fluid and
being
in communication with the annular chambers of the corresponding discs which
are fixed in a pack on the driving shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages and features of the present invention will become clear
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from the following detailed description thereof which is given with reference
to
the appended drawings which are provided purely by way of non-limiting
example and in which:
- Fig. 1 is a perspective view of an abrasive disc for a multiple disc
grinding machine according to the invention;
- Fig. 2 is a view in axial section of the disc of Fig. 1; and
- Fig. 3 is a view in partial section of a multiple disc grinding machine
equipped with abrasive discs according to the invention.
DETAILED DESCRIPTION
With reference to the appended drawings, an abrasive disc for a
multiple disc grinding machine embodied in accordance with the present
invention is shown overall by 1. A grinding machine equipped with a plurality
of
abrasive discs closed in a pack on a driving shaft 3 of the grinding machine
which may be caused to rotate about an axis X is shown by 2. Only the cutting
disc 1 will be described in detail below, as the features described mirror
those
of the remaining discs of the pack mounted on the shaft 3.
The multiple disc grinding machine designed in this way is for
particular use for the processing of stone and like materials but could be
used
in other fields, for instance for the processing of ceramics, refractory
materials
or glass.
The disc 1 comprises a disc-shaped support la which is axially
symmetrical with a main axis shown by Y in the drawings and bears a
circumferential rim 4 on which abrasive cutting sectors 5 are applied.
The transverse thickness of the disc at its central portion, measured parallel
to
the axis Y, is shown by 6.
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The support la is also provided with a central hole 7 for
connection to an end portion 3a of the driving shaft 3 which causes the disc
to
rotate during cutting operations involving tangential contact between the rim
4
and the material to be processed.
The connection hole 7 has a first cylindrical through section 7a
which comes into coupling contact with the driving shaft 3 and a second
cylindrical through section 7b extending as an axial continuation of the first
section, this second section having a diameter greater than the first section.
As
a result of this feature, an annular chamber shown by 8 is formed at the
location of the second through section 7b, following connection with the shaft
3,
whose function will be explained in detail in the following description. The
sequence of through holes 7a, 7b extends through the entire transverse
thickness 6 of the disc, so that the section 7b extends, with its free end, up
to
the location of a front transverse surface of the disc shown by 9. This
surface
extends with an annular configuration from the hole 7 in the direction of the
rim 4 over a predetermined radial development. When the discs are mounted
as a pack on the shaft 3, the surface 9 of each disc abuts against the
adjacent
disc and as a result of the axial clamping action of the pack of discs, this
surface acts as a friction member designed to prevent the relative sliding of
adjacent discs.
The front surface 9 is provided with at least one radial recess,
shown by 10, which extends from the annular chamber 8 in the direction of the
rim 4 radially including the whole surface. A preferred choice, shown in the
appended drawings, is to provide three recesses 10 angularly spaced from one
another at regular intervals (with an angular pitch of 120 ), although the
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invention could function with other configurations. The recesses 10 may also
be
readily provided on the front surface 9 by respective radial milling
operations
on the surface 9.
As is clearly shown in Fig. 3, once the discs are positioned as a
pack on the shaft 3, the annular chamber 8 is connected in fluid communication
with each of the recesses 10 so as to ensure a passage for a coolant fluid
accumulated in the chamber and conveyed to the exterior of the disc via the
recess 10.
The driving shaft of the grinding machine 2 is provided with an
internal axial duct 11 for supplying the coolant fluid, which duct is
continued by
one or a plurality of radial end ducts 12 opening at the location of
cylindrical
shell of the end portion of the shaft 3 designed to house the abrasive discs.
It is advantageous for the thickness 6 of the disc 1 in contact with the shaft
to
be smaller than the diameter of the hole 12 provided on the shaft, so as to
ensure a passage for the coolant fluid from the chamber 8 containing the fluid
to the recesses 10, which recesses 10 therefore form a kind of channel for
supplying the fluid to the exterior of the disc in order to distribute the
fluid to
the processing zones close to the abrasive sectors of the circumferential rim
4.
The provision of the annular chamber 8 in fluid connection with the recesses
10
therefore makes it possible for the coolant fluid to be accumulated in the
chamber and then to flow radially, under the centrifugal effect of the
rotation of
the grinding machine, along the recesses so as efficiently to reach the
processing zone of the abrasive sectors of the discs and thus to ensure the
cooling of the surfaces in relative contact of the discs and the material
being
processed.
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In a variant of the invention the cylindrical shell of the driving
shaft 3 intended to receive the cutting discs, may be provided with a groove
13
(or a plurality of grooves 13) extending axially along the whole pack of discs
and in fluid communication with the supply holes 12 of the coolant fluid. This
groove may improve the distribution effect of the coolant fluid to each
annular
chamber of the discs mounted in a pack on the shaft, as shown in Fig. 3, in
the
lower axial section of the grinding machine.
The invention thus achieves the objects set out above and
provides many advantages over known solutions.
A main advantage lies in the simpler structure and operation of
the cooling system which the invention applies to multiple disc cooling
systems,
avoiding the use of specific distribution members for the coolant fluid, such
as
the bushings or like distributors for which known solutions make provision.
This
simpler structure is advantageously reflected by easier use, especially as
regards operations to mount the pack of discs on the grinding machine and
remove it therefrom, a major advantage when taking account of the fact that
these tools have to be readily and rapidly interchangeable as a result of the
wear of the abrasive profiles to which they are subject when processing
materials.
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