PULLEY FOR MULTI-WIRE MACHINE TOOLS

Field of the invention

The present invention generally finds application in the technical field of machines for working stone, cementitious or the like materials and particularly relates to a pulley for multi-wire machine tools, which is designed to have wound thereon one or more flexible elements, more precisely cutting wires in multi-wire machines for cutting stone blocks to obtain a plurality of plates.

Background of the invention

Multi-wire machines for cutting blocks of stone material, concrete or the like into a plurality of slabs are known to be composed of a bearing structure with two or more rollers or drums mounted thereto for closed-loop winding of a plurality of flexible elements such as diamond wires.

Particularly, an array of return pulleys may be mounted to a common shaft for adjusting the tension of each of the cutting wires.

Typically, for each of the cutting wires to remain within a predetermined cutting plane and not slip over the outer surface of its drum or return pulley during rotation, both the drums and the pulleys have one or more peripheral grooves which define respective housings for the wound wires.

Also, the grooves can also receive an anti-wear element, generally an annular elastomeric sheath which has the main purpose of increasing friction to prevent wire slipping.

Anti-wear elements prevent the cutting wires from being in direct contact with the drums and pulleys, thereby preserving the latter from the unavoidable wear caused by wire slipping. Therefore, non intact liners shall have to be periodically

replaced.

A similar solution is disclosed, for example, in US2958323, in which a stone cutting apparatus comprises a wheel with a plurality of axially offset grooves at its peripheral region, for receiving corresponding annular anti-wear elements made of rubber.

Nevertheless, prior art configurations suffer from certain recognized drawbacks, especially because anti-wear elements are typically fitted onto the cylinder or pulley within their respective grooves and held therein by their own elasticity.

Particularly, anti-wear elements are usually force-fitted in the groove or the elastomeric material is directly cured on the pulley body.

In the former case, anti-wear elements can receive a single cutting wire and the addition of another wire, for instance to change the slab thickness, would require the cylinder to have one or more free grooves and/or one pulley to be added to the array.

In the latter case, replacement of an anti-wear element would require the whole pulley to be removed, which is a very long and burdensome operation.

Also, prior art solutions do not efficiently ensure firm attachment of the anti-wear element, and there is a relatively high risk that it may come off its housing groove, which would involve machine shutdown as well as probable damages to the cutting wire or the whole multi-wire machine.

Summary of the invention

The object of this invention is to overcome the above drawbacks, by providing a pulley for multi-wire machine tools that is highly efficient and relatively cost- effective.

A particular object is to provide a pulley in which the anti-wear protection is firmly and safely attached to the pulley body.

A further object is to provide a pulley that allows simple and quick replacement of the anti-wear elements fitted on its peripheral region.

Yet another object of the present invention is to provide a pulley that, when used in combination with a multi-wire machine for slabbing blocks of stone or the like materials, allows slab thickness adjustments without requiring the addition or removal of additional pulleys.

Another object of the present invention is to provide a pulley with a variable number of flexible elements mounted thereto.

Another important object of the invention is to provide a pulley assembly that allows simple and quick change of slab thickness as obtained by cutting a block of stone material.

These and other objects, as better explained hereafter, are fulfilled by a pulley for multi-wire machines as defined in claim 1, comprising a disk-shaped body with a substantially central axis of rotation and an outer peripheral region, an anti-wear protection associated with the outer peripheral region of said disk-shaped body and having an annular shape with at least one outer peripheral groove for receiving at least one flexible element.

The invention is characterized in that the anti-wear protection has an annular appendix, extending radially inwards from the side opposite said at least one groove, said disk-shaped body having an annular channel at said outer peripheral region, which is designed to receive and firmly hold said annular appendix of said anti-wear protection.

This particular configuration will ensure firm attachment of the anti-wear protection

to the pulley body and prevent it from slipping during rotation of the pulley thereby causing the flexible element to come off its housing.

Advantageously, the annular protection may have a plurality of substantially parallel and axially spaced annular grooves on its outer side, each defining a respective housing for a flexible element.

Thus, when these pulleys are used in combination with multi-wire machines for cutting blocks into a plurality of slabs, slab thickness adjustment can be simply obtained by displacing the cutting wire wound on the pulley into one of the grooves formed in the protection, without requiring the addition of another pulley.

In another aspect, the present invention relates to a pulley assembly as defined in claim 13.

Brief description of the drawings

Further features and advantages of the invention will be more apparent upon reading of the detailed description of a preferred, non-exclusive embodiment of a pulley according to the invention, which is described as a non-limiting example with the help of the annexed drawings, in which:

FIG. 1 is a perspective view of a pulley of the invention;

FIG. 2 is a front view of the pulley of FIG. 1 ;

FIG. 3 is a partial perspective view of the pulley of FIG. 1 ; FIG. 4 is an exploded view of the pulley of FIG. 1 ;

FIG. 5 is a sectional view of the pulley of the invention, as taken along the plane /-/ of FIG. 2;

FIG. 6 shows enlarged sectional views of a detail of a pulley of the invention in several preferred configurations for the anti-wear protection and with the disk- shaped body in a first preferred configuration;

FIG. 7 shows enlarged sectional views of a detail of a pulley of the invention in several preferred configurations for the anti-wear protection and with the disk-

shaped body in a second preferred configuration;

FIG. 8 is a sectional front view of a pulley assembly of the invention in a preferred configuration.

Detailed description of a preferred embodiment

Referring to the above figures, a pulley of the invention, generally designated by numeral 1 , may be designed to be wound with cutting wires of multi-wire machine tools for slabbing blocks of stone, marble, concrete or the like.

Particularly, the pulley may be used as a return and/or tensioning pulley in an assembly for returning and/or tensioning cutting wires or other flexible elements, mounted to the frame of a machine tool, not shown.

As shown in FIG. 1 , a pulley of the invention comprises a disk-shaped body 2 with a substantially central axis of rotation X and an outer peripheral region 3, an anti- wear protection 4 associated with the outer peripheral region 3 of the disk-shaped body 2 and having an annular shape with at least one outer peripheral groove 5 designed to receive at least one flexible element, such as a cutting wire, a drive belt or the like, not shown but commonly known.

In accordance with a peculiar feature of the invention, the anti-wear protection 4 has an annular appendix 6, extending radially inwardly from the side opposite to the groove 5 formed on the outer surface 7 of the anti-wear protection.

Also, the disk-shaped body 2 has an annular channel 8 at its outer peripheral region 3, which is designed to receive and firmly hold the radial appendix 6 of the anti-wear protection 4.

This will nullify the risk that the anti-wear protection 4 may come off the body 2 of the pulley 1 as the latter rotates, and that it may thereby cause misalignment of the flexible element relative to its normal working plane.

This would forcibly require a machine shutdown and may cause damages not only to the pulley 1 but to the whole machine or the product being processed as well.

According to a preferred, non-exclusive embodiment, the disk-shaped body 2 of the pulley 1 may be formed of a material of relatively high rigidity, such as a metal or metal alloys.

The anti-wear protection 4 may be formed of a material of lower rigidity than the material of the disk-shaped body 2 and will be preferably made of an elastomeric material.

The pulley 1 may be mounted to a drive or driven shaft, not shown, associated with the bearing frame of a machine tool, such as a multi-wire machine.

Furthermore, the pulley 1 may be mounted in such a position that its central axis of rotation X can be transversely offset, possibly at an adjustable distance, from the axis of rotation of the shaft, thereby affording independent tensioning of the flexible element wound thereon.

A particular embodiment of the pulley 1 of the invention is shown in FIGS. 3 to 5, illustrating the particular interlock joint between the radial appendix 6 in the peripheral channel 8 of the disk-shaped body.

In this particular configuration, which does not intend to limit the scope of the invention, each of the radial appendix 6 and the peripheral channel 8 may have a substantially continuous radial extension, coincident with that of the outer peripheral region of the disk-shaped body 2.

Nonetheless, in an alternative embodiment, not shown, both the radial appendix 6 and the channel 8 may be discontinuous and composed of separate sections whose overall extension is shorter than the perimeter of the anti-wear protection 4 and the peripheral region 3 of the disk-shaped body 2 respectively.

As shown in FIG. 4, the anti-wear protection 4 may be formed as an open loop so that, when it is coupled to the disk-shaped body, it has a substantially transverse discontinuity 21 at its end faces 22, 22'.

This particular configuration will further facilitate introduction of the radial appendix 6 in the channel 8, because an end portion of the former will simply have to be fitted in the latter, for the whole anti-wear protection 4 to slide along the peripheral region 3 of the disk-shaped body 2.

On the other hand, FIG. 6 and FIG. 7 show a number of possible configurations for the pulley 1 of the invention with the disk-shaped body 2 in two possible preferred, non exclusive embodiments of the present invention.

As is clearly shown, the appendix 6 and the channel 8 may have substantially complementary cross sections.

Also, they may be advantageously mated with a predetermined interference to generate an elastic force fit with increased stability.

As used herein, the term "cross section" is intended to indicate a section of the pulley 1 that is taken in any plane of the set of planes that pass through the central axis X of the disk-shaped body 2.

For instance, the channel 8 and the radial appendix 6 may have respective rounded cross sections, with substantially equal and opposite radiuses of curvature, like in the configuration of FIG. 6a and FIG. 7a, or prismatic or frustoconical cross sections, as shown in FIG. 6b and FIG. 7b.

In the latter case, the inner side 9 of the anti-wear protection 4 may not perfectly adhere to the outer face 10 of the disk-shaped body 2, for easier assembly.

FIG. 6c and FIG. 7c show two additional configurations in which both the

peripheral channel 8 and the radial appendix 6 may have respective prismatic cross sections, each with an outer portion 11 , 12 having a predetermined substantially constant axial width ai, a ₂ and an inner portion, 13 and 14 respectively, having an axial width a ₃ , a ₄ larger than the axial width a-[, a ₂ of the corresponding outer portion 11 , 12.

Thus, the channel 8 may define an abutment surface 15 for holding the radial appendix 6 and making the fit even firmer.

Also, in the configurations of FIGS. 6d and 6a and of FIG. 7d, the abutment surface 15 may be defined by a substantially convex outer portion 11 of the channel 8 that is adapted for engagement with a substantially concave outer portion 12 of the radial appendix 6.

Furthermore, to facilitate introduction of the radial appendix 6 in the groove 8, the latter may have a maximum radial extension η larger than the maximum radial dimension r ₂ of the appendix 6.

FIGS. 6 and 7 also show that the outer side 7 of the annular protection 4 may have a plurality of substantially parallel and axially spaced annular grooves 5, 5', 5", ..., each defining a respective housing for a flexible element.

Particularly, three substantially similar annular grooves 5, 5', 5" are shown in Figures 6a to 6d and in FIG. 7, whereas two grooves 5, 5' are shown in Figure 6e.

Nonetheless, the number of annular grooves 5, 5', 5", ... may be even greater than in the figures, depending on the maximum axial dimension a of the disk- shaped body 2, and on the diameter of the flexible elements to be wound on the pulley 1.

The inner curvature of the grooves 5, 5', 5", ... may also change according to the particular configuration of the flexible elements.

According to the configuration as shown in FIG. 6, the disk-shaped body 2 also has clamp means 16 for clamping the appendix 6 in the peripheral channel 8, which are adapted to adjust the axial width ai, a ₂ of the channel 8, thereby facilitating introduction of the radial appendix 6 or adapting the configuration of the channel 8 to that of the appendix 6, e.g. by adjusting the interference of this fit.

The clamp means 16 may include an annular slit 17 that may extend from the bottom 18 of the channel 8 over a predetermined radial extension r ₃ such as to impart limited elasticity to such slit 17.

This allows adjustment of the axial width a ₅ of the slit and the axial width ai, a ₂ of the channel 8 for easier introduction of the annular appendix 6.

Moreover, the clamp means 16 may include a plurality of through holes, generally designated by numeral 19, which are spaced from each other and have respective axes Y substantially parallel to each other and to the central axis X of the disk- shaped body 2.

The holes 19 may be formed at the radial slit 17 and be engaged by corresponding clamp members, generally designated by numeral 20, of the screw or the like type, as more clearly shown in FIG. 4, to change the maximum axial dimension a ₅ of the radial slit 17 in response to the specific operational requirements.

Finally, FIG. 8 is a sectional view of a particular configuration of a pulley assembly 23 to be wound with flexible elements, particularly cutting wires, which is composed of a plurality of pulleys 1 of the invention.

In the illustrated configuration, the pulleys 1 of the assembly 23 may have respective central axes of rotation X independent of each other and may be mounted to a common support axis, not shown, so that each may translate along its respective transverse direction, substantially orthogonal to the support axis, for independent tensioning of the corresponding flexible elements wound thereon.

However, in an alternative configuration, not shown, the assembly 23 may be formed of an array of pulleys 1 having a common axis of rotation X and possibly constrained together to define a unit body, and translate together in integral relationship.

Particularly, the assembly 23 may be designed to define a cylinder to be wound with flexible elements, which is formed of a substantially cylindrical main body 2 having a plurality of annular channel 8 on its peripheral region 3.

Each channel 8 may be designed to mate with a respective anti-wear protection 4 as described above, having a predetermined number of outer grooves 5, 5', 5",...

The above disclosure clearly shows that the invention fulfills the intended objects and particularly meets the requirement of providing a pulley to be wound with flexible elements, in which the anti-wear protection 4 is firmly attached to the body 2.

Thanks to the particular configuration of the anti-wear protection 4, the position of the flexible elements on the pulley may be changed in a relatively simple and quick manner, to adjust, for instance, the thickness of one or more slabs to be obtained from a block cut by a plurality of cutting wires.

The pulley and assembly of this invention are susceptible to a number of changes or variants, within the inventive concept disclosed in the appended claims. All the details thereof may be replaced by other technically equivalent parts, and the materials may vary depending on different needs, without departure from the scope of the invention.

While the pulley and assembly have been described with particular reference to the accompanying figures, the numerals referred to in the disclosure and claims are only used for the sake of a better intelligibility of the invention and shall not be intended to limit the claimed scope in any manner.