Abrasive disc for a multiple disc grinding machine, in particular for processing stone and like materials, and a grinding machine including said disc

Abstract

An abrasive disc for a multiple disc grinding machine is described, including a disc-shaped support having a circumferential rim on which the 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, in which 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. The further disc includes 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.

1 . An abrasive disc for a multiple disc grinding machine, the abrasive disc comprising:
 a disc-shaped support ( 1   a ) having a circumferential rim ( 4 ) on which an abrasive material is disposed to form an abrasive outer edge of the abrasive disc and a central hole ( 7 ) for fitting on to a driving shaft ( 3 ) of the grinding machine, said hole ( 7 ) extending through an axial thickness of the disc-shaped support ( 1   a ), wherein a portion of said central hole ( 7 ) has a diameter greater than the diameter of the shaft ( 3 ) to which the abrasive disc is adapted to be connected, such that an annular chamber ( 8 ) is formed in the thickness of the support,   at least a front surface of the disc-shaped support ( 1   a ) having at least one radial recess ( 10 ) formed therein the at least one radial recess extending from said annular chamber ( 8 ) towards the circumferential rim ( 4 ) of said disc, in such a way that a coolant fluid fed into the driving shaft ( 3 ) can accumulate in said annular chamber ( 8 ) of the disc shaped support and can then flow through said radial recess ( 10 ) towards the abrasive edge of said 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.   
     
     
         2 . The disc according to  claim 1 , in which three radial recesses ( 10 ) are provided on said front surface ( 9 ), the recesses being spaced apart angularly at regular intervals. 
     
     
         3 . The disc according to  claim 1 , in which said portion of the central hole ( 7 ) forming said annular chamber ( 8 ) extends as a continuation of a portion of the hole ( 7 ) intended to contact the driving shaft ( 3 ) of the grinding machine when the disc is connected to it. 
     
     
         4 . A multiple disc grinding machine comprising a driving shaft ( 3 ) receiving thereon a plurality of abrasive discs ( 1 ) combined in a pack on said shaft ( 3 ), each of said discs being defined in  claim 1 . 
     
     
         5 . The multiple disc grinding machine according to  claim 4 , in which said driving shaft ( 3 ) comprises at least one hole ( 17 ) for the feed of coolant fluid, the hole extending radially in the end portion of said shaft ( 3 ) which is intended to receive the plurality of cutting discs ( 1 ), and opening on a cylindrical shell which comes into contact with the discs, in which a transverse thickness of the discs is smaller than a diameter of said at least one coolant fluid feed hole ( 12 ) in the shaft, so as to permit the passage of fluid from said feed hole ( 12 ) to the annular chamber of the corresponding disc and thence to the corresponding recess ( 10 ). 
     
     
         6 . The multiple disc grinding machine according to  claim 5 , further comprising at least one channel ( 13 ) extending axially in the cylindrical shell of the end of the driving shaft intended to be connected to said discs, said channel ( 13 ) communicating with said radial hole ( 12 ) for the feed of the coolant fluid and being capable of bringing said hole ( 12 ) into communication with the annular chambers ( 8 ) of the corresponding discs ( 1 ) which are fixed in a pack on the driving shaft ( 3 ). 
     
     
         7 . The multiple disc grinding machine as defined in  claim 4 , 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. 
     
     
         8 . The abrasive disc as defined in  claim 1 , wherein the central hole is defined in the disc-shaped support by a first cylindrical surface which comes into coupling contact with the driving shaft and a second cylindrical surface which axially extends from the first cylindrical surface and is radially outward therefrom, the second cylindrical surface being said portion of the central hole having the diameter greater than that of the shaft and thus of the first cylindrical surface, such that the first cylindrical surface couples the abrasive disc to the driving shaft with a continuous coupling contact and the second cylindrical surface defines said continuous annular chamber which extends about the circumference of the abrasive disc and through which fluid flows into said radial recesses. 
     
     
         9 . A plurality of abrasive discs for a multiple disc grinding machine, the plurality of abrasive discs being combined in an axially-stacked pack adapted to be received on a driving shaft of the multiple disc grinding machine, each of said plurality of abrasive discs being as defined in  claim 1 . 
     
     
         10 . 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 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.   
     
     
         11 . The multiple disc grinding machine as defined in  claim 10 , 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. 
     
     
         12 . The multiple disc grinding machine as defined in  claim 6 , 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. 
     
     
         13 . 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 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.   
     
     
         14 . The multiple disc grinding machine as defined in  claim 13 , wherein the driving shaft includes at least one supply hole for feeding coolant fluid, the supply 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 supply hole for the feed of coolant fluid in the shaft, so as to permit the passage of fluid from said supply hole to the annular chamber of the corresponding disc and thence to the corresponding recess. 
     
     
         15 . The multiple disc grinding machine as defined in  claim 4 , wherein the central hole is defined in the disc-shaped support by a first cylindrical surface which comes into coupling contact with the driving shaft and a second cylindrical surface which axially extends from the first cylindrical surface, the second cylindrical surface being said portion of the central hole having the diameter greater than that of the shaft and thus of the first cylindrical surface, such that the first cylindrical surface couples the abrasive disc to the driving shaft with a continuous coupling contact and the second cylindrical surface defines said continuous annular chamber which extends about the circumference of the abrasive disc and through which fluid flows into said radial recesses.