Patent Application
20200030940
The present invention relates to an abrasive grinding wheel, e.g. with a depressed or flat centre, or a cutting disc, an emery or cutting grinding wheel, and a method for producing it.
As is known, a grinding wheel is essentially comprised of a disc-shaped body made of an abrasive mixture bound by a resin, reinforced by reinforcements constituted by one or more fabric nets, by one or two metallic annular elements, commonly known as washers or ring nuts, which delimit the hole for attaching the grinding wheel to the shaft of the cutting machine, and by an optional label made of paper or other applied material commonly used, which adheres to one of the two faces of the grinding wheel (usually to the back one).
In the manufacture and sale of the resinoid bonded abrasive grinding wheels, e.g. of cutting discs, a significant difficulty has always been represented by the remarkable number of attachment holes adopted for the various needs of manufacturers of cutting machines. In particular, it is found that about four or five quality types of grinding wheels can be formed in various formats, e.g. with outer diameters of 300, 350, 400 and 500 mm. Each of such grinding wheels can then be configured so as to have at least seven different attachment hole diameters. Obviously, for the manufacturer and for business, this situation determines at least thirty-five different configuration possibilities of the cutting discs to be produced to fulfil the market needs, in addition to the cost for the manufacturer of having to continuously replace in the forming moulds of such cutting discs, the pins that create the central holes for following order requests sometimes for just a few dozen items.
Furthermore, this is added to the need for the manufacturer to store reinforcement nets and metal washers with various central holes.
This is why for a long time grinding wheel manufacturers have tried to remedy this problem by supplying washers for adapting the attachment hole made of plastic materials or aluminium included in various sizes in the packets of discs. However, unfortunately this solution, which is also expensive, has the problem of the poor stability of these adaptation washers once assembled on the grinding wheel. This poor stability often creates problems in the assembly operations of cutting discs on the machines. These solutions are also often totally rejected by the users and the retailers.
Other known solutions over past times have envisaged valid and stable insertion systems of washers, especially plastic, in the centre of the attachment holes of the cutting discs, for the adherence inside the hole of a crown of plastic material injected hot with special moulds and with injection machinery.
This is certainly an optimal solution from the mechanical perspective, but is very expensive in terms of the systems (moulds) needed for producing it, and not very versatile according to market requirements as, in order to be implemented, it requires substantial orders in order to be made cost-effective and advantageous for the manufacturer.
An object of the present invention is to overcome the mentioned drawbacks of the prior art, within the context of a simple and rational solution and at a contained cost.
Such purposes are accomplished by the characteristics of the invention given in the independent claims. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.
The invention, particularly, makes available an abrasive grinding wheel that comprises an annular body made of abrasive material provided with a central hole and a reducing ring provided with a central attachment hole, wherein the reducing ring is inserted into the central hole so that the attachment hole of the reducing ring is coaxial with respect to the central hole of the annular body, wherein the reducing ring comprises two opposing enlarged axial end stretches (of which at least one of the two is obtained by plastic deformation for example by riveting) configured to axially lock the reducing ring to the central hole of the annular body. Thanks to such solution, the drawbacks of the prior art are overcome making available an abrasive grinding wheel, i.e. a cutting disc, with a reducing ring firmly fixed to the abrasive annular body of the grinding wheel itself which can initially have a single attachment hole for all the formats (outer diameters) and types (composition of the abrasive mixtures) in which the grinding wheel can be made, which can then be easily and effectively adapted according to the specific customer requirements and requests.
Advantageously, the central hole of the annular body can comprise two opposing axial end stretches having enlarged sections with respect to a central stretch having a tapered section axially interposed between the two axial end stretches having enlarged sections, the opposing axial end stretches of the reducing ring substantially engaging to measure with the axial end stretches of the central hole of the annular body.
Again, according to an advantageous aspect of the invention, the reducing ring can be made of a plastic material, e.g. thermosetting.
A further aspect of the invention makes available a method for producing abrasive grinding wheels that comprises:
Thanks to such solution a quick, economically advantageous (compared to the known methods), safe and repeatable method is made available for producing an abrasive grinding wheel (or a cutting disc) with a reducing ring placed inside it. Advantageously, the fixing of the reducing ring by means of riveting can comprise plastically deforming at least one edge proximal to an axial end of the reducing ring.
Yet another aspect of the invention can provide for the formation of the annular body comprising the creation of the central hole with an axially variable cross section.
Within the context of such aspect, the realisation of the central hole can provide for the formation of two opposing end stretches having enlarged sections at two axial ends of the central hole and at least one central stretch having a tapered section axially interposed between the two end stretches.
Furthermore, the insertion of the reducing ring inside the central hole can provide for the coaxial insertion of the reducing ring in the central hole, so that an enlarged axial end stretch of the reducing ring substantially engages to measure with one of the end stretches of the central hole and, wherein the fixing of the reducing ring to the annular body through riveting of the reducing ring provides for riveting a further axial end stretch of the reducing ring so as to radially enlarge such further axial end stretch of the reducing ring; the further axial end stretch of the reducing ring thus radially enlarged engaging to measure with the other end stretch of the central hole.
According to a further aspect of the invention, the fixing of the reducing ring to the annular body can be performed through hot riveting of the reducing ring.
In this way the riveting of the reducing ring is substantially irreversible and the reducing ring is firmly fixed to the inside of the abrasive annular body of the grinding wheel.
According to an advantageous aspect of the invention, the production method can provide for the step of enlargement through milling of the attachment hole of the reducing ring.
In this way, the abrasive grinding wheel (or cutting disc), e.g. previously stored by the manufacturer or the retailer in a format that is universal so to speak, wherein the attachment hole has a standard diameter regardless of the outer diameter of the abrasive annular body of the grinding wheel and regardless of the composition of the abrasive mixture, can then be customised according to the customer's specific requirements in a short time and also advantageously for small orders from the customer or small production batches.
Further characteristics and advantages of the invention will become clear from reading the following description provided as a non-limiting example, with the help of the figures illustrated in the attached tables.
With particular reference to such figures, 10 indicates overall an abrasive grinding wheel, e.g. of the cutting disc type, i.e. a flat abrasive grinding wheel or with a depressed centre.
The grinding wheel 10 comprises an annular body 20, provided with a central axis A, which annular body 20 is for example substantially flat (see figures) or with a depressed centre (not shown).
The annular body 20 is substantially circular and is provided with a central hole 21 that is coaxial with respect to the annular body 20, passing through in an axial direction from one side to the other of the annular body 20.
The annular body 20 has an outer diameter substantially comprised between 250 mm and 500 mm, e.g. equal to 250 mm or 300 mm or 400 mm or 500 mm.
The annular body 20 comprises two opposing faces 22 and 23, of which one front face 22 and one rear opposing face 23, which are, for example parallel to each other overall and orthogonal to the central axis A of the annular body 20.
The annular body 20 has a substantially layered structure and has at least one or more layers of abrasive mixture.
Each layer of abrasive mixture (once pressed and fired) defines a substantially monolithic body.
For example, each layer of abrasive mixture is made of a mixture of abrasive powders that is compacted and firmly bound to a binding resin.
In practice, the layer of abrasive mixture is obtained through pressing a mixture of a loose powder of abrasive material, e.g. abrasive material such as natural corundum, sand, recovered artificial corundum or the like, sol-gel abrasives or sintered ceramics, zirconium corundums, or the like, and mixed with an appropriate binder, e.g. based on binding resins, for example phenolic resins, liquid resins and/or powdered resins, and possibly modified with epoxy, phenoxy and/or other resins, modified with organic and/or vegetable or synthetic compounds, and other types of polyimide resin etc., and/or with additives and fillers.
For example, the quantity of resin is comprised between 15% and 20% by weight with respect to the weight of the abrasive material powder mixture.
The abrasive material of the layer of abrasive mixture has particle size substantially comprised between 120 and 12 in mesh (however, the use of abrasive mixtures with a larger or smaller particle size than the range, according to requirements, is not excluded).
The annular body 20 comprises one or more reinforcement nets each substantially incorporated into the layer of abrasive mixture or interposed between them.
Each reinforcement net is substantially annular and has a hole in the centre with a diameter greater than or equal to the (minimum) diameter of the central hole 21 of the annular body 20.
In practice, the layer of abrasive mixture (or the layers of abrasive mixture) surround(s), in particular axially, the entire (lower and upper) surface of the reinforcement net.
Furthermore, the layer of abrasive mixture can also incorporate more than one reinforcement net.
The central hole 21 of the annular body 20 preferably has an axially variable cross section, e.g. variable in stretches.
In particular, the central hole 21 of the annular body 20 comprises a first stretch 210, for example with a circular cross section (i.e. orthogonal to the central axis A) wherein such first stretch 210 has a first diameter d1 that is the minimum diameter of the central hole 21.
The central hole 21 of the annular body 20 then comprises a second stretch 211, e.g. with a circular cross section, wherein such second stretch 211 has a larger second diameter d2 than the first diameter d1 of the first stretch 210 (e.g. equal to the maximum diameter of the central hole 21).
Again, the central hole 21 of the annular body 20 then comprises a third stretch 212, e.g. with a circular cross section, wherein such third stretch 212 has a larger third diameter d3 than the first diameter d1 of the first stretch 210, preferably but not necessarily equal to the second diameter of the second stretch 211 (e.g. equal to the maximum diameter of the central hole 21).
For example, the first diameter d1 of the first stretch 210 is predefined, i.e. it is a fixed diameter regardless of the outer diameter of the annular body 20 and, preferably, equal for all the annular bodies 20 even with different outer diameters.
Even more preferably, the first diameter d1 of the first stretch 210 is greater than the most common inner diameters of the standard attachment holes present on the market for such type of grinding wheels (cutting discs), e.g. it is greater than 35 mm, e.g. it is equal to 40 mm.
The second diameter d2 and the third diameter d3 can be calculated according to the first diameter d2 and the thickness of the annular body 20 (or the axial length of the central hole 21), e.g. through the following relationship:
d1=d2=d1+k;
where k is a whole submultiple of the thickness of the annular body 20 (or the axial length of the central hole 21), e.g. it is equal to half the length of the annular body 20 or a third of the thickness of the annular body 20.
Preferably, the first stretch 210 is (central or) axially interposed between the second stretch 211 and the third stretch 212.
In that case, the second stretch 211 and the third stretch 212 are axial end stretches of the central hole 21 and lead directly to a respective face 22 and 23 of the annular body 20.
In practice, the second stretch 211 and the third stretch 212 define opposing axial ends with an enlarged section of the central hole 21 with respect to the tapered section axially interposed between them defined by the first stretch 210.
In a first embodiment shown in
In practice, the first stretch 210 is defined by the minimum section of the central hole 21 placed on the median plane of the grinding wheel 10 (or of the central hole 21) orthogonal to the central axis A and is connected with two respective substantially truncated cone (rounded) surfaces, that define the second stretch 211 and the third stretch 212, at the opposite ends of the central hole 21, with the maximum section.
In a second embodiment shown in
The first stretch 210 is then connected with two respective substantially truncated cone shaped surfaces (substantially inclined by 45° with respect to the central axis A), which define the second stretch 211 and the third stretch 212, at the opposite ends of the central hole 21, with the maximum section.
Finally, the grinding wheel 10—as shown in
The washer 24 is fixed to the rear face 23 of the annular body 20 of the grinding wheel 10, for example for a limited radial stretch of the annular body 20 itself.
The washer 24 comprises a thin hollow central shank 24 that is substantially inserted to measure in the central hole 21 and that has the same shape (of the axial stretches described above) as the central hole 21.
In practice, the hollow central shank 24 radially delimits, without altering the shape thereof described above, the central hole 21.
On the rear face 23 of the annular body 20 of the grinding wheel 10, even after the forming (and firing of the grinding wheel itself, as will be described more clearly below), a label 25 can be placed (visible only in
The grinding wheel 10 then comprises a reducing ring 30, which is configured to (substantially) reduce the through section of the central hole 21 of the annular body 20, as will be better described below, until reaching an inner diameter substantially equal to the outer diameter of the rotary shaft of the cutting machine for which the grinding wheel 10 is intended.
The reducing ring 30 comprises a substantially circular disc-shaped body 31 provided with a central axis B.
Preferably but not necessarily, the disc-shaped body 31 is provided with a central attachment hole 32, e.g. coaxial with respect to the disc-shaped body 31, which passes through in the axial direction from one side to the other side of the disc shaped body 31.
The attachment hole 32 is for example cylindrical with a constant section along the entire axial extension thereof.
Preferably, the diameter D0 of the attachment hole 32 is smaller than the most common inner diameters of the standard attachment holes present on the market for such type of grinding wheels (cutting discs), e.g. it is equal to 20 mm.
For example, the diameter D0 of the attachment hole 32 is predefined, i.e. it is a fixed diameter regardless of the outer diameter of the annular body 20 (and of the inner diameter of the central hole 21) and, preferably, it is initially the same for all the grinding wheels 10.
For example, the diameter D0 of the attachment hole 32 is substantially comprised between 80% and 25% of the first diameter d1 of the central hole 21, preferably comprised between 80% and 50% of the first diameter d1 of the central hole 21, in the example, equal to about half of the first diameter d1 of the central hole 21.
The attachment hole 32, when the reducing ring 30 engages the central hole 21 of the annular body 20, is coaxial to the annular body 20 (or to the central hole 21 thereof).
The disc-shaped body 31 comprises two opposing faces 33 and 34, of which one front face 33 and one rear opposing face 34 which are, for example, parallel to each other overall and orthogonal to the central axis B of the disc-shaped body 31.
The thickness (or axial length) of the disc-shaped body 31 is defined by the distance between the faces 33 and 34 thereof, which is preferably equal to (or slightly larger than) the thickness of the grinding wheel 10, or the axial length of the central hole 21 of the annular body 20 thereof.
The disc-shaped body 31 has a shaped outer jacket which, once inserted into the central hole 21 of the annular body 20 of the grinding wheel 10, is substantially complementary to the shape of the central hole 21 of the annular body 20 for which it is intended, so as to define a (substantially perfect) shape connection.
The outer jacket of the disc-shaped body 31 preferably has an axially variable cross section, e.g. variable in stretches.
In particular, the outer jacket of the disc-shaped body 31 comprises a first stretch 310 for example with a circular cross section (or orthogonal to the central axis A), in which such first stretch 310 has a first diameter D1 that is the minimum diameter of the outer jacket of the disc-shaped body 31 and is substantially equal (or slightly smaller) than the first (minimum) diameter d1 of the first stretch 210 of the central hole 21.
The outer jacket of the disc-shaped body 31 then comprises a second stretch 311, e.g. with a circular cross section, wherein such second stretch 311 has a second diameter D2 greater than the first diameter D1 of the first stretch 310, e.g. equal to the maximum diameter of the outer jacket of the disc-shaped body 31 and is substantially equal to (or slightly smaller than) the second (maximum) diameter d2 of the second stretch 211 of the central hole 21.
Again, the outer jacket of the disc-shaped body 31—once it has been firmly inserted into the central hole 21 of the annular body 20 of the grinding wheel 10—comprises a third stretch 312, e.g. with a circular cross section, wherein such third stretch 312 has a third diameter D3 greater than the first diameter D1 of the first stretch 310, preferably but not necessarily equal to the second diameter D2 of the second stretch 311, e.g. equal to the maximum diameter of the outer jacket of the disc-shaped body 31 and is substantially equal to (or slightly smaller than) the second (maximum) diameter d3 of the third stretch 212 of the central hole 21.
Preferably, the first stretch 310 of the outer jacket of the disc-shaped body 31 is axially interposed between the second stretch 311 and the third stretch 312.
In that case, the second stretch 311 and the third stretch 312 are axial end stretches of the disc-shaped body 31 and are connected directly to a respective face 33 and 34 of the disc-shaped body 31 (defining at least one end portion thereof).
In particular, the second stretch 311 defines a first enlarged axial end of the disc-shaped body 31, i.e. that enlarges in a radial direction (with respect to the central axis B), with respect to the first stretch 310 and the third stretch 312 defines an opposing second enlarged axial end of the disc-shaped body 31, i.e. that enlarges in a radial direction (with respect to the central axis B), with respect to the first stretch 310.
In other words, the second stretch 311 and the third stretch 312 define opposing axial ends with an enlarged section of the disc-shaped body 31 with respect to the tapered section axially interposed between them defined by the first stretch 310.
For example, the second stretch 311 is defined by an annular crown that projects radially from the disc-shaped body 31.
The annular crown that defines such second stretch 311 has a substantially conical shape whose largest base is substantially coplanar to one of the faces 33 and 34, in the example the rear face 34.
For example, the third stretch 312, once the grinding wheel 10 is definitively formed, is defined by a further annular crown that projects radially from the disc-shaped body 31.
Such further annular crown that defines such third stretch 312 has a substantially conical shape whose largest base is substantially coplanar to the other one of the faces 33 and 34, in the example the front face 33.
Preferably, the annular crown that defines the second stretch 311 is symmetrical to the further annular crown that defines the third stretch 312 with respect to a median plane of the disc-shaped body 31 orthogonal to the central axis B.
In a first embodiment shown in
In practice, the first stretch 310 is defined by the minimum section of the outer jacket of the disc-shaped body 31 placed on the median plane of the disc-shaped body orthogonal to the central axis B and is connected with two respective substantially truncated cone (rounded) surfaces, that define the second stretch 311 and the third stretch 312, at the opposite ends of the disc-shaped body 31, with the maximum section.
Such conformation of the disc-shaped body is intended to be inserted in the first embodiment into the central hole 21 of the annular body 20 shown in
In a second embodiment shown in
As will be better described below, the third stretch 312, or the annular crown that defines it, is obtained through (irreversible) plastic deformation of an edge 313 (see
For example, the third stretch 312 is obtained through (hot) riveting.
For example, the edge 313 is movable (by irreversible plastic deformation) from an initial position, in which it projects axially from the front face 33 of the disc-shaped body 31 and is contained within the radial dimensions defined by the first stretch 310, to a final (definitive) position, in which it projects radially defining said third stretch 312.
The edge 313 is for example a circular crown for its whole extension, but could also be defined by a plurality of circular crown shaped stretches separated from each other.
In practice, when the edge 313 is in its initial position, the disc-shaped body 31 can be axially inserted into the central hole 21 of the annular body 20 (on the side of the front face 33, or by first inserting the edge 313 and then the first stretch 310, until the second stretch 311 of the disc-shaped body 31 abuts and is housed in the third stretch 212 of the central hole 21).
When instead the edge 313 comes into its final position, it is housed (to measure) in the second stretch 211 of the central hole 21 of the annular body 20, in practice radially and/or axially contained therein, in fact retaining or being retained axially inside the central hole 21 without the possibility of being axially pulled out from (and rotating with respect to) the annular body 20.
For example, the third stretch 312 of the disc-shaped body 31, or the edge 313 brought into its final position, is adapted to adhere to at least one surface (portion) of the second stretch 211 of the central hole 21 of the annular body 20, e.g. through an adhesive (preferably, but not necessarily, defined by the binding resin that constitutes the annular body 20 of the grinding wheel 10 or the material—thermally softened and then hardened—that constitutes the edge itself).
In a preferred embodiment the disc-shaped body 30 is made overall of a plastic material, e.g. a heat deformable plastic material, preferably nylon in some of the numerous appropriate types.
Preferably, the disc-shaped body 30 is made overall of a plastic material having a higher softening temperature than the softening (or melting) temperature of the binding resin used for realizing the annular body 20 of the grinding wheel 10.
Alternatively, it is possible to provide for the disc-shaped body 30 to be made overall of a different material, e.g. metal or another material sufficiently rigid to be able to define an edge 313 adapted to be plastically deformable (due to the shape or size or composition thereof).
In light of the above description, the method for producing a grinding wheel 10 as described above is as follows.
The method firstly envisages the step of forming an annular body 20 (see
The step of forming the annular body 20 takes place through pressing a mixture of abrasive powders and binding resin (possibly stratified with the interposition of reinforcement meshes), as described above, e.g. through a specific forming mould (as known to a person skilled in the art).
The central hole 21 is formed with the aforementioned specifications, e.g. covered or not by the aforesaid washer 24.
The rear face 23 of the annular body 20 can be covered at least partially by the label 25 during the forming step, or preferably, it can be made to adhere, through relevant adhesives, at a later time according to the requirements.
The method then envisages arranging at least one reducing ring 30 as described above, e.g. preformed, e.g. through injection moulding or another suitable forming method.
At the start, the reducing ring 30 is configured so that the edge 313 is in its initial position described above.
At this point, the method envisages the step of coaxially inserting (see
Such insertion step can be realized in an automated or semi-automated way by a specific insertion machine.
Furthermore, such insertion step can be realized by axially inserting the disc-shaped body 31 into the central hole 21 of the annular body 20 on the side of the front face 33, or by first inserting the edge 313 and then the first stretch 310, until the second stretch 311 of the disc-shaped body 31 abuts and is housed in the third stretch 212 of the central hole 21.
In this position, in which the second stretch 311 of the disc-shaped body 31 abuts and is housed in the third stretch 212 of the central hole 21 the rear face 34 of the reducing ring 30 is substantially coplanar to the rear face 23 of the annular body 20 (or slightly protruding therefrom, e.g. by 1 or 2 tenths of a millimetre).
Furthermore, in this position, in which the second stretch 311 of the disc-shaped body 31 abuts and is housed in the third stretch 212 of the central hole 21, the edge 313 in its initial position projects axially beyond the central hole 21 (and beyond the plane defined by the front face 22 of the annular body 20 of the grinding wheel 10).
At this point the method envisages the step of fixing (see
For example, the fixing step is performed through riveting the second stretch 312 (or the edge 313) of the reducing ring 30; in such riveting the edge 313 is plastically deformed so that it is brought irreversibly from its initial position to its final position.
In such final position the edge 313 prevents the reducing ring 30 being axially pulled out from the annular body 20.
For example, the riveting is hot riveting, e.g. it envisages heating, until softening (e.g. to a temperature comprised around 250° C.), the edge 313, so that it can—once softened—be brought into its final position and, in fact, occupy the annular volume interposed between the reducing ring (with the edge 313 in the initial position) and the second stretch 211 of the central hole 21 of the annular body 20. Such hot riveting also envisages cooling (or leaving to cool) the edge 313 plastically deformed in the final position, until the hardening thereof, in fact making the plastic deformation undergone by the edge 313 irreversible.
The hot riveting also allows the adhesion of the third stretch 312 of the reducing ring 30 to the walls of the (second stretch 211) of the central hole 21 of the annular body 20.
Preferably, the riveting 313 is performed through a specific riveting tool 40 depicted in
The riveting tool 40 comprises for example a circular crown, e.g. made of metal material, defining a contact surface, adapted to come into contact with the edge 313, which is for example covered by non-stick materials to promote the detachment of the edge 313 once it has been plastically deformed (through softening). The riveting tool 40 then comprises, as usual, heating elements 41, such as electric resistors (e.g. provided with thermostats) adapted to heat it, e.g. the contact surface of the riveting tool 40.
The riveting tool 40 is then axially movable with respect to the reducing ring 30, so as to be able to exert a (slight) thrust or axial pressure on the edge 313 that is translated into axial and radial deformation of the edge 313 itself.
The riveting step can even last a few seconds.
At the end of such step, the edge 313 has been brought into the final position and has provided the aforesaid third stretch 312 of the disc-shaped body 31 of the reducing ring 30, as illustrated in
In this final position, in which the third stretch 312 of the disc-shaped body 31 abuts and is housed (to measure) in the second stretch 211 of the central hole 21 the front face 33 of the reducing ring 30 is substantially coplanar to the rear face 22 of the annular body 20 (or slightly protruding therefrom, e.g. by 1 or 2 tenths of a millimetre at the most).
The method also envisages the step of firing the grinding wheel 10, or the annular body 20 thereof.
Such firing step can take place prior to the step of inserting the reducing ring 30 in the central hole 21 of the annular body 20 or following the fixing step (by riveting) of the reducing ring 30 to the annular body 20.
Such firing step envisages subjecting the annular body 20 (or the entire grinding wheel 10) to a thermal firing treatment, e.g. in specific polymerization ovens, in which the polymerization of the binding resin is completed as it stably solidifies and retains the abrasive mixture that constitutes the annular body 20 of the grinding wheel 10.
In practice, the annular body 20 is subjected to a thermal cycle that envisages the insertion thereof in an oven at a temperature substantially comprised between 80° and 200° C. for a time substantially comprised between 1 and 50 hours, or may be fired in situ in the same pressing mould, where the latter is provided with heating means.
Such firing step, where performed following the fixing step (by riveting) of the reducing ring 30 to the annular body 20 is such as not to deform the reducing ring 30.
The grinding wheel 10 thus finished or to be finished therefore has an annular body 20 provided with a central hole 21 inside which a reducing ring 30 is firmly fixed, in turn with an attachment hole 32, wherein the attachment hole 32 has the aforesaid diameter D0 (a lot smaller than the minimum diameter of the central hole 21).
The method for producing the grinding wheel 10 can, further, envisage the step of applying (see
In this way the label 25, as well as the information related to the grinding wheel 10, can bear customized information related to the retailer and/or the manufacturer or other required information. In practice, such solution allows the affixing of customized labels (customer brand) and the specification thereon of the instructions and characteristics of use of the grinding wheel 10.
The method finally envisages the step of enlarging the attachment hole 32 of the reducing ring 30.
For example, it is possible to enlarge the attachment hole 32 according to customer requests according to requirements, or to bring it to compatible dimensions with the diameter of the rotary shaft of the cutting machine in which the grinding wheel 10 is to be assembled.
Preferably, the step of enlarging the attachment hole 32 can be performed through milling (see
Such milling operation can be performed through a relevant milling tool 50, which has, for example, a milling cutter with increasing diameters, in stretches.
The first diameter at the free end of the milling cutter can be equal to the diameter D0 of the attachment hole 32 of the reducing ring 30, in that way the coaxial insertion of the milling cutter in the attachment hole 32 of the reducing ring 30 is guided by the cylindrical coupling between the first diameter and the attachment hole 32 of the reducing ring 30.
By axially sinking the milling cutter into the reducing ring as far as the desired axial position corresponding to the diameter of the attachment hole 32, the attachment hole 32 will be enlarged to the desired dimension, e.g. 22 mm, 25 mm or 32 mm or other customizable sizes.
For example, the maximum diameter to which it is possible to enlarge the attachment hole 32 is for example less than or equal to 80% of the first diameter d1 of the central hole 21 of the annular body 20.
This solution therefore allows the grinding wheel 10 manufacturer to prepare and store grinding wheels 10 provided with a reducing ring 30 having a smaller common attachment hole 32 for a certain type of grinding wheels 10 (e.g. for cutting discs); such attachment hole 32 could have a diameter equal to 20 mm.
Such reducing ring 30 provided with the attachment hole 32 common to all would be assembled on all the annular bodies 20 in the quality type variants (e.g. 5-6 different abrasive mixtures), in fact constituting a stock of grinding wheels 10 to be finished, whose finalization can envisage only the preparation (enlargement) of the attachment hole 32, also of a few dozen pieces at a time, quickly and cheaply when an order from the distributor/customer is finalized.
What has been described above could be performed, being equipped with simple equipment even for use by distributors (if different from the manufacturer), avoiding useless and expensive storage of too many different types of grinding wheels in which the only variant is the attachment hole.
The invention thus conceived can undergo numerous modifications and variants all of which are covered by the inventive concept.
Moreover, all of the details can be replaced by other technically equivalent elements.
In practice, the materials used, as well as the contingent shapes and sizes, can be whatever according to the requirements without for this reason departing from the scope of protection of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102018000007516 | Jul 2018 | IT | national |
