EP3216563A1

EP3216563A1 - Cup grinding wheel for working slab edges

Info

Publication number: EP3216563A1
Application number: EP17155694.7A
Authority: EP
Inventors: Domenico PRIVITERA
Original assignee: Up Tools Ltd
Current assignee: Up Tools Ltd
Priority date: 2016-02-12
Filing date: 2017-02-10
Publication date: 2017-09-13
Anticipated expiration: 2037-02-10
Also published as: EP3216563B1; ITUB20160714A1

Abstract

A cup grinding wheel (10) for working slab edges, which comprises:
- a shaped backing pad (11) for fixing to a spindle,
- an abrasive annular body (12), fixed to the shaped backing pad (11), with a cylindrical lateral face (13) and a front working face (14).

The abrasive annular body (12) comprises a continuous external abrasive crown (15) and a segmented internal abrasive crown (16), and has an annular curvilinear channel (17) that extends on the front working face (14) so as to separate the continuous external abrasive crown (15) and the segmented internal abrasive crown (16).

Description

The present invention relates to a cup grinding wheel for working slab edges.
In particular, the field to which the invention relates is grinding, and in particular the forming of slab edges of stone materials, both natural and synthetic, of ceramic materials and of glassy materials.
Generally such working is carried out using diamond abrasive cup grinding wheels, with which a series of operations is carried out according to the final result that it is desired to obtain; such operations can be cutting, roughing, lapping, polishing and brightening.
For the ordered execution of one or more of such operations, cup grinding wheels are mounted on respective spindles, aligned in sequence on automatic rectilinear milling machines, capable of working on a single side or on two opposite sides simultaneously.
In such machines, the spindles do not move and the slabs to be worked are advanced by way of belt or strap systems.
As shown for the purposes of example in Figure 1, representing the background art, a cup grinding wheel A is generally constituted by a backing pad B, or wheel body, which is contoured so as to be installed on a spindle of a milling machine, and by a crown, or abrasive ring C, mounted on the backing pad and adapted to work in contact with an edge of a slab in order to confer the desired characteristics thereon.
Such abrasive annular body has a cylindrical lateral face D and a working front face E, the latter being the one that comes into contact with the edge of a slab to be worked.
The abrasive ring C can have a continuous shape as in Figure 1, or it can be segmented G, like the abrasive ring F in Figure 2, according to whether one wishes to obtain a working with better finishing capacities, as in the case of the continuous abrasive ring C, or with better cutting capacities, as in the case of the segmented abrasive ring G.
Most cup grinding wheels work wet, with water or with water with coolant added, distributed by external means.
In this manner the front working face, in contact with the edge of the slab during working, is cleaner and better cooled.
Such cup grinding wheels, although appreciated and widespread, have some drawbacks.
In fact, by its nature every wheel used in the various steps leaves working lines, indicating what in the jargon are called "grinding traces", on the edge of the slab.
In order to increase the degree of finishing that it is desired to obtain, i.e. to reduce these working lines, one or more passes are carried out on the edge of the slab to be worked, in the various working phases.
This can occur by working an edge with cup grinding wheels with increasingly smaller diamond/abrasive granulometries, and this is the system used most, so that the greater the number of aligned tools on a machine, the better the finishing of the worked edge.
However, the greater the number of aligned tools, the longer the machine needs to be, and therefore for a high quality working of the slab edges particularly long machines are needed, with corresponding encumbrances that have a negative effect on the layout of the workspace.
Furthermore, for lapping, polishing and brightening operations, cup grinding wheels need to be used that have a continuous abrasive ring, for the reasons explained above, and such grinding wheels have cooling limitations, since the jet of coolant originating from the backing pad hardly succeeds in evenly cooling the entire body of the abrasive ring, and furthermore such jet is poorly distributed over the surface being worked; by contrast, grinding wheels with a segmented abrasive ring, used for roughing or cutting operations, are better cooled since the refrigerant liquid passes through the interspaces between the sectors, thus spreading out better and resulting in both a more even cooling of the cup grinding wheel and a better cleaning of the surface being worked.
The aim of the present invention is to provide a cup grinding wheel for working slab edges that is capable of overcoming the above mentioned drawbacks of the known art.
Within this aim, an object of the invention is to provide a cup grinding wheel that is capable of limiting the working lines on the edge of the slab being worked.
Another object of the invention is to provide a cup grinding wheel that makes it possible to set up machines that are shorter overall with respect to conventional machines, i.e. that are capable of optimal performance levels with a smaller number of cup grinding wheels with respect to conventional machines.
Another object of the invention is to provide a cup grinding wheel that is capable of polishing operations and which at the same time can be optimally cooled.
This aim and these and other objects which will become better evident hereinafter are achieved by a cup grinding wheel according to claim 1.
Further characteristics and advantages of the invention will become better apparent from the detailed description that follows of a preferred, but not exclusive, embodiment of a cup grinding wheel according to the invention, which is illustrated for the purposes of non-limiting example in the accompanying drawings wherein:

Figure 1 is a view of a conventional cup grinding wheel;
Figure 2 is a view of another conventional cup grinding wheel;
Figure 3 is a view of a cup grinding wheel according to the invention;
Figure 4 is a schematic view of a cup grinding wheel in action on an edge of a slab;
Figure 5 is a schematic view of an example of a working trajectory of the work surface of the cup grinding wheel according to the invention.

With reference to the figures, a cup grinding wheel according to the invention is generally designated with the reference numeral 10.
The cup grinding wheel 10 comprises:

a shaped backing pad 11 for fixing to a spindle,
an abrasive annular body 12, fixed to the shaped backing pad 11; the abrasive annular body 12 has a cylindrical lateral face 13 and a front working face 14.

The peculiarity of the cup grinding wheel 10 according to the invention consists in that the abrasive annular body 12 comprises a continuous external abrasive crown 15 and a segmented internal abrasive crown 16.
The annular body 12 has an annular curvilinear channel 17 that extends on the front working face 14 so as to separate the continuous external abrasive crown 15 and the segmented internal abrasive crown 16.
The annular curvilinear channel 17 extends in depth starting from the front working face 14 in an axial direction X toward the backing pad 11, where X is the direction of the rotation axis of the cup grinding wheel 10.
The sectors of the segmented abrasive ring 16 are designated with the reference numerals 18, 19 and 20.
A sector 19 is separated from a laterally adjacent sector 18 and 20 by an interspace 21 and 22, which also extends in depth starting from the front working face 14 in an axial direction X toward the backing pad 11.
In particular, the curvilinear channel 17 extends on the working face 14 along a sinusoidal line Z with respect to a reference circumference Z1.
Such sinusoidal line Z is shown in Figure 5 with respect to the linear path of the reference circumference Z1, taking as a reference some significant points P1, P2, P3, P4, P5 of its trajectory, indicated in Figure 4 and shown in the same graph in Figure 5.
In Figure 4 a generic slab is shown with the reference numeral 30 and an edge thereof being worked is designated with the reference numeral 31.
The advancement direction of the slab 30 with respect to the cup grinding wheel 10 is indicated with the letter Y.
In the working band 25 between the outer and inner circumferences Z2 and Z3, which are tangential respectively to the maxima and to the minima of the sinusoidal path Z, the cup grinding wheel 10 according to the invention works on the face of the edge 31 being worked, alternating a predominantly cutting action when it is in contact with the segmented internal abrasive crown 16 and a predominantly finishing action when it is in contact with the continuous external abrasive crown 15.
The oscillating character of the working performed by such cup grinding wheel 10 makes it possible to obtain, with a single cup grinding wheel according to the invention, the result that usually in the known art is carried out by two separate cup grinding wheels, one with a continuous abrasive crown and one with a segmented abrasive crown.
Furthermore, by virtue of the oscillating progression of the working of the external crown 15, the elimination is obtained of the working lines typical of conventional cup grinding wheels, i.e. the "grinding traces".
What is more, by virtue of the segmented internal crown 16, the cup grinding wheel 10 according to the invention is optimally cooled in the manner of a conventional cup grinding wheel with a segmented abrasive crown, thus incorporating the finishing capability of cup grinding wheels with a continuous abrasive crown and the optimal cooling capability of cup grinding wheels with a segmented abrasive crown.
By virtue of a cup grinding wheel according to the invention, it is possible to increase the working speed without limiting the quality of the work.
The cup grinding wheel 10 according to the invention, by incorporating two tools in one, makes it possible to set up machines for working slab edges with fewer aligned spindles, and which are therefore shorter overall, with advantages in terms of cost and of space occupation.
The two abrasive crowns 15 and 16 can be provided with abrasive material of the same or different granulometries, according to the necessities and technical requirements.
The abrasive material, in any case, should be understood as being of conventional type.
In practice it has been found that the invention fully achieves the intended aim and objects.
In particular, with the invention a cup grinding wheel has been devised that is capable of limiting the working lines on the edge of the slab being worked.
What is more, with the invention a cup grinding wheel has been devised that makes it possible to set up machines that are shorter overall with respect to conventional machines, i.e. that are capable of optimal performance levels with a smaller number of cup grinding wheels with respect to conventional machines.
Furthermore, with the invention a cup grinding wheel has been devised that is capable of polishing operations and which at the same time can be optimally cooled.
The invention, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements.
In practice the components and the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.
The disclosures in Italian Patent Application No. 102016000014447 ( UB2016A000714 ) from which this application claims priority are incorporated herein by reference.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

A cup grinding wheel (10) for working slab edges, which comprises:
- a shaped backing pad (11) for fixing to a spindle,

- an abrasive annular body (12), fixed to said shaped backing pad (11), with a cylindrical lateral face (13) and a front working face (14),
characterized in that said abrasive annular body (12) comprises a continuous external abrasive crown (15) and a segmented internal abrasive crown (16), and has an annular curvilinear channel (17) that extends on the front working face (14) so as to separate said continuous external abrasive crown (15) and said segmented internal abrasive crown (16).
The cup grinding wheel according to claim 1, characterized in that said annular curvilinear channel (17) extends in depth starting from the front working face (14) in an axial direction (X) toward the backing pad (11), where the axial direction (X) is the direction of the rotation axis of the cup grinding wheel (10).
The cup grinding wheel according to one or more of the preceding claims, characterized in that a sector (19) is separated from a laterally adjacent sector (18, 20) by an interspace (21, 22), which also extends in depth starting from the front working face (14) in an axial direction (X) toward the backing pad (11).
The cup grinding wheel according to one or more of the preceding claims, characterized in that said curvilinear channel (17) extends on the working face (14) along a sinusoidal line (Z) with respect to a reference circumference (Z1).