The present invention relates to a magnetic guide for a chain of a chain conveyor.

In particular, the present invention relates to a magnetic curved guide for a chain of a chain conveyor.

Chain means in particular a so-called "conveyor chain", even more in particular, a "conveyor chain" for curved paths of the type comprising a plurality of links that are articulated together by means of hinging, and each of which has a hinging portion with the adjacent links and a generally plate-like portion that extends transversely to the movement direction of the chain and that defines a resting surface for products to be transported.

These chains are closed in a loop on themselves and are wound about driving and idler wheels to form a conveyor for transporting products resting on the upper branch or forward branch of the chain itself.

As is known, these chains are assembled along guides that comprise:

- a forward guide, along which at least one forward channel is formed in which the hinging portions of the links forming the forward branch of the chain slide and which is delimited by a corresponding pair of forward rails, each of which defines a respective sliding surface along which a part of the plate-like portion of the links forming the forward branch of the chain slides, and

- a return guide, along which at least one return channel is formed in which the hinging portions of the links forming the return branch of the chain slide and which is delimited by a corresponding pair of return rails, each of which defines a respective sliding surface along which a part of the plate-like portion of the links forming the return branch of the chain slides .

The chain links are held in the guide against radial and circumferential forces by the interaction between their hinging portions and the forward and return channels in which they slide.

The chain links are held in the guide against the detachment forces having component orthogonal to the sliding surfaces defined by the forward and return rails or with magnetic interaction means or with mechanical means acting by impediment.

According to a first known solution such as for example, described in EP0903307, the forward branch of the chain is held in the guide by magnetic interaction means, while the return branch is held in the guide by mechanical means.

The magnetic interaction means comprise a plurality of pairs of magnets that are distributed, spaced apart, along the longitudinal extension of the guide below the forward channel. Each pair of magnets is formed by two ferromagnetic bodies joined together by a ferromagnetic plate to jointly form a U-shaped magnet whose branches face towards the forward channel. Such a configuration allows confining and amplifying the magnetic field towards the forward channel. The links of the chain here are made at least partly of magnetisable material, in particular their articulating pins are made of magnetisable material so as to interact with the magnetic field generated by the pairs of magnets .

The return branch of the chain instead is held in the guide by mechanical means formed by grooves that extend continuously along the outer sides of the return rails and each forming a respective channel in which the ends (wings) of the plate-like portions of the chain links forming the return branch, slide.

It is apparent that as the thickness of the chain links vary, and in particular their plate-like portions, it is necessary to implement different return guides, it being necessary to modify the height of the respective grooves for holding the links.

Such solution is schematically shown in figures 13A, 13B and 13C, in which the guide 200 comprises:

- a U-shaped upper body 201 defining the forward guide,

- a lower body 202 defining the return guide and in which there are housed the pairs of magnets each formed by two magnetic bodies 203 joined by a ferromagnetic plate 204 to form a U-shaped magnet whose branches are facing towards the forward guide.

Figure 14 schematically shows the distribution of the magnetic field generated by the magnetic bodies 203 joined together by the ferromagnetic plate 204.

The lower body 202 has respective grooves 205, 205 ' at the outer sides of the respective rails, in which grooves the wings of the links forming the return branch of the chain, slide; it is worth noting that the grooves 205, 205' have different height as a function of the thickness of the plate-like portions of the chain links .

As the chain varies therefore, it is necessary to implement a different lower body 202, with apparent disadvantages in terms of production and assembly costs of the guide.

It has also been proposed to use magnetic holding means to hold the chain not only along the forward guide, but also along the return guide.

So for example, US5027942 describes the use of magnets for holding the chain links both along the forward guide and along the return guide. The solution described in such document refers to chain links wholly made of ferromagnetic material and interacting with magnets housed in each forward and return rail.

The use of magnetic holding means to hold the chain both along the forward guide and also along the return guide is also described in W02016 / 131879A1 (Rexnord) .

According to what is described in such document, containment seats of magnetic bodies are formed along the longitudinal extension of the guide, the magnetic bodies being adapted to interact with the articulating pin of the chain links, a pin that is made of ferromagnetic material.

Two pairs of magnetic bodies are arranged in each containment seat, in which the magnetic bodies of each pair are joined together by a ferromagnetic plate so as to form a respective U-shaped magnet. The ferromagnetic plate is common to the two pairs of magnetic bodies housed in the same containment seat. See for example, figures IF and 1G of W02016 / 131879A1.

Alternatively, again according to what is described in such document, two series of containment seats for magnetic bodies adapted to interact with the articulating pin of the chain links are formed along the longitudinal extension of the guide: a first series receives pairs of magnets adapted to hold the forward branch of the chain along the respective forward guide, and a second series receives pairs of magnets adapted to hold the return branch of the chain along the respective return guide. Also in this case, the magnets of each pair of magnets are connected to one another by a respective ferromagnetic plate to form a relative U- shaped magnet.

Such a solution however requires the use of a plurality of magnetic components (two pairs of magnets and relative ferromagnetic plate for each containment seat) which increase the production costs and which complicate the assembly and disassembly operations of the guide. Moreover, it requires for the guide body to have a sufficient height to obtain therein containment seats that are sufficiently deep to receive the two pairs of magnets and the ferromagnetic plate interposed therebetween, with subsequent increase of production costs of such body and increased volumes of the whole guide .

Typically, each of the magnetic bodies has a height of 8 mm and the relative ferromagnetic plate has a height (thickness) equal to 3 mm.

According to what is described in W02016 / 131879A1 , it is possible to contain the sizes in height of the guide body by implementing - in place of the two pairs of U-shaped magnets (each formed by two magnetic bodies connected by a relative ferromagnetic plate) - also only one single permanent magnet made of boron- neodymium oriented with its axis perpendicular to the bottom of the forward and return channels.

However, such a solution is extremely expensive. According to the prior art, as for example described in the aforesaid documents EP0903307 and W02016 / 131879A1 , the guide is made in two bodies: an upper body in which the forward guide is formed and a lower body in which the return guide is formed.

According to the prior art, these two bodies are mechanically coupled to each other for example, by means of a plurality of screws and, as described in EP0903307, also with a shape coupling.

As is known, the upper body is more subject to wear and is to be periodically replaced.

To this end, according to the prior art, it is necessary to disassemble the whole guide and intervene with tools to individually unscrew all the screws fixing the upper body to the lower body; the inverse screwing and assembly operations are necessary to assemble the new upper body on the lower body and reposition the guiding in its seat.

These operations are particularly lengthy and laborious and require the interruption of the chain conveyor for a non-negligible time.

The object of the present invention is to obviate the drawbacks of the prior art. A particular object of the present invention is to provide a magnetic guide, in particular a magnetic curved guide, for a chain of a chain conveyor which allows to magnetically hold the chain links forming both the forward branch and the return branch respectively along forward guide and return guide in a stable and secure manner with the use of a reduced number of components with respect to the known solutions, also having contained costs and volumes.

Another object of the present invention is to provide a magnetic guide, in particular a magnetic curved guide, for a chain of a chain conveyor that is simple both structurally and from a constructional viewpoint, and that has contained volumes.

Another object of the present invention is to provide a magnetic guide, in particular a magnetic curved guide, for a chain of a chain conveyor that allows making the assembly and disassembly operations of the relative components and the relative wear parts particularly easy and quick.

These objects according to the present invention are achieved by providing a magnetic guide, in particular a magnetic curved guide, for a chain of a chain conveyor, as disclosed in claim 1.

Further characteristics are provided in the dependent claims.

The characteristics and advantages of a magnetic guide, in particular a magnetic curved guide, for a chain of a chain conveyor according to the present invention will be more apparent from the following description, which is to be understood as exemplifying and not limiting, with reference to the schematic attached drawings, wherein:

figure 1 is an axonometric view of a possible embodiment of a magnetic curved guide according to the present invention;

figure 2 is a side elevation view of figure 1 ;

figure 3 is an axonometric view of a further possible embodiment of a magnetic curved guide according to the present invention;

figure 4 is an exploded view of figure 3;

figure 5 is a top plan view of figure 3;

figure 6 is a section according to the plane IV-IV of figure 5;

figure 7 is a section according to the plane V-V of figure 5;

figure 8 is a section according to the plane VI-VI of figure 5;

figures 9 and 10 show the distribution of the magnetic field at a section of a possible embodiment of the guide according to the present invention, respectively without the chain of the chain conveyor and with the chain of the chain conveyor;

figures 11 and 12 show the distribution of the magnetic field at a section like the one of figure 6, respectively without the chain of the chain conveyor and with the chain of the chain conveyor;

figures 13A, 13B and 13C diagrammatically show the cross-section of a magnetic curved guide according to the prior art described for example in EP0903307B1;

figure 14 shows the distribution of the magnetic field at a section of the forward guide of a magnetic curved guide according to the prior art.

With reference to the accompanying figures, a magnetic guide 10 for guiding a chain 100 of a chain conveyor is shown.

It is worth noting that adjectives in the following description such as "lower" and "upper" refer to the guide 10 considered in the usual conditions of use. Adjectives such as "longitudinal" and "transverse" refer to the extension of the guide 10 respectively along the guide path and transversely thereto.

The chain 100 is of the type known to those skilled in the art and does not form the object of the present invention.

The chain 100 is only diagrammatically illustrated in certain accompanying figures.

The chain 100 is at least partially made of a magnetisable material and comprises a plurality of links 101 hinged together at respective hinging portions 102 by means of respective pins 104 and each of which is provided with a plate-like portion 103 defining a transportation surface on which products to be transported are arranged resting.

The links 101 of the chain 100 may be made at least partly of a magnetisable material or of a plastic material in which a load of particles made of a magnetisable material is dispersed.

In an alternative and preferred embodiment, the links 101 may be made of a plastic material and the pins 104 which articulate the links 101 between one another are made of a magnetisable material.

Magnetisable material in particular means a ferromagnetic material.

The chain 100 is wound like a loop about driving and idler wheels (not depicted and of known type) and defines a forward branch 100A and a return branch 100B (see figures 8 and 10) . The forward branch 100A is the upper branch of the chain 100 which is active in transporting products. The return branch 100B is the lower branch of the chain 100.

In particular, the guide 10 is arched to define a curve.

The guide 10 comprises at least one body 11 in which there are defined:

- at least one forward guide for guiding the forward branch 100A of the chain, this forward guide comprising at least one forward channel 12 in which the hinging portions 102 of the links 101 forming the forward branch 100A are received and at least one pair of corresponding forward rails 13 arranged at the sides of the forward channel 12 and each defining a sliding surface 13a for the sliding thereupon of at least one part of the plate-like portion 103 of the links 101 forming the forward branch 100A;

- at least one return guide for guiding the return branch 100B of the chain 100, this return guide comprising at least one return channel 14 in which the hinging portions 102 of the links 101 forming the return branch 100B are received and at least one pair of corresponding return rails 15 arranged at the sides of the return channel 14 and each defining a sliding surface 15a for the sliding thereupon of at least one part of the plate-like portion 103 of the links forming the return branch 100B;

- magnetic interaction means that are coupled with the body 11 and that are interacting with the links 101 or with their hinging pins 104 to attract the links 101 with at least part of their plate-like portions 103 against the respective said sliding surfaces 13a and 15a defined both by said forward rails 13 of the forward guide and by the return rails 15 of the return guide.

That is, the chain 100 is held in the guide by magnetic interaction both along the forward guide and along the return guide. Holding in the guide means holding the links 101 against detachment forces with component orthogonal to the sliding plane defined by the sliding surfaces 13a of the forward rails 13 and to the sliding plane defined by the sliding surfaces 15a of the return rails 15; the holding of the links 101 with respect to radial and circumferential forces is given by the forward channel 12 and by the return channel 14.

In particular, the chain 100 is held in the guide only by magnetic interaction both along the forward guide and along the return guide, there not being mechanical means that hold the chain 100 in the guide along the forward guide or along the return guide against detachment forces with component orthogonal to the plane defined by the sliding surfaces 13a and 15a.

According to the present invention, the magnetic interaction means comprise a plurality of pairs of magnets CM that are distributed, spaced apart, along the longitudinal extension of the guide 10 and that are housed in corresponding containment seats 16 formed in the at least one body 11 defined between the forward channel 12 and the return channel 14. Each pair of magnets CM is housed in a respective containment seat 16.

Each pair of magnets CM comprises only two magnetic bodies 17A and 17B, each of which has a height h measured perpendicular to the sliding surfaces 13a or 15a comprised between 8 mm and 25 mm: 8 mm < h < 25 mm, greater than 8 mm and less than or equal to 25 mm.

The two magnetic bodies 17A and 17B of each pair of magnets CM are identical to each other in shape and sizes and, in a preferred embodiment, each of them has a height h equal to 16 mm, aside from production tolerances .

As mentioned above, each pair of magnets CM comprises only two magnetic bodies 17A and 17B, that means in particular that each pair of magnets CM does not comprise any further magnetic component, in particular ferromagnetic component, interposed between the two magnetic bodies 17A and 17B or that magnetically connects the two magnetic bodies 17A and 17B to each other. In particular, the magnetic bodies 17A and 17B of each pair of magnets CM are not connected to each other or joined by any ferromagnetic or metallic plate suitable to form an airgap, which is completely absent. The two magnetic bodies 17A and 17B of each pair of magnets CM therefore do not form a U- shaped magnet or a pair of U-shaped magnets. The two magnetic bodies 17A and 17B of each pair of magnets CM are housed in the respective containment seat 16 so as to be spaced apart from each other and separated by a non-zero distance d measured parallel to the width of the forward channel 12 and of the return channel 14.

An insert made of non-magnetic material is advantageously inserted between the two magnetic bodies 17A and 17B of each pair of magnets CM; such insert may be at least partly formed by a rib or a septum formed in the containment seat 16 and/or at least partly by a rib or septum formed in a closing cap of the containment seat 16 described in detail later.

In a preferred embodiment, each of the two magnetic bodies 17A and 17B of each pair of magnets CM consists of a single body, that is a body obtained in a single piece, made of ferromagnetic material with a single north pole and a single south pole. One of the two magnetic bodies of each pair of magnets CM (the magnetic body 17A in the accompanying drawings) is arranged with its north pole oriented towards the bottom of the return channel 14 and the other of the two magnetic bodies of each pair of magnets CM (the magnetic body 17B in the accompanying drawings) is arranged with its north pole oriented towards the bottom of the forward channel 12.

This embodiment is particularly advantageous because producing each of the two magnetic bodies 17A and 17B in one piece as a single body has significantly lower costs than the ones required to produce magnetic bodies having equal shape and sizes by assembly of a plurality of separate elements made of ferromagnetic material .

However, the possibility is not excluded for each of the two magnetic bodies 17A and 17B of each pair of magnets CM to consist of at least two elements made of ferromagnetic material, each with a single north pole and a single south pole and overlapping one another with the north pole of one facing and overlapping the south pole of the other to form a stack ending in a respective north pole and in a respective south pole. For example, each of the two magnetic bodies 17A and 17B of each pair of magnets CM could consist of two elements made of ferromagnetic material each having height equal to /2, equal to for example 8mm. Also in such case, one of the two magnetic bodies of each pair of magnets CM (the magnetic body 17A in the accompanying drawings) is arranged with its north pole oriented towards the bottom of the return channel 14 and the other of the two magnetic bodies of each pair of magnets CM (the magnetic body 17B in the accompanying drawings) is arranged with its north pole oriented towards the bottom of the forward channel 12.

Each of the two magnetic bodies 17A and 17B is made of ferromagnetic material, of the ferrite type for example and in particular, of grade CER S30 ferrite. It is excluded for the two magnetic bodies 17A and 17B to consist of boron-neodymium permanent magnets.

In practice, it has been noted that the use of pairs of magnets CM, each of which consisting only of two magnetic bodies 17A and 17B made of ferromagnetic material, each of which having height h comprised between 8 mm and 25 mm (8 mm < h < 25 mm) and not connected to each other by any ferromagnetic plate, is sufficient to generate a magnetic field adapted to ensure the holding in the guide both of the forward branch 100A and of the return branch 100B of the chain respectively along the forward guide and along the return guide, without requiring the use of any auxiliary holding means, such as for example, mechanical means.

The two magnetic bodies 17A and 17B of each pair of magnets CM are arranged symmetrically with respect to a median plane which longitudinally cuts the forward channel 12 and the return channel 14.

The two magnetic bodies 17A and 17B of each pair of magnets CM have a width measured along the width of the forward channel 12 and of the return channel 14 and are arranged in such a manner as to extend partly below the bottom 12a of the forward channel 12 and of the bottom 14a of the return channel 14 and partly below the respective forward rail 13 and the respective return rail 15 immediately adjacent thereto.

With reference to figures 1 and 2, the body 11 is constituted by two bodies 22 and 23 that are arranged one on the other and coupled together for example mechanically by means of a form fitting and/or screws or the like. Each one of the two bodies can be obtained as a U-shaped single body so as to define the respective forward channel 12 and return channel 14. One or both of the two bodies 22 and 23 has cavities forming the containment seats 16 for containing the two magnetic bodies 17A and 17B of each pair CM. An analogous structure is shown in figures 9 and 10. The two bodies could also have a shape different from that shown and/or be formed by a plurality of assembled components .

Each containment seat 16 consists of a hollow obtained in the body 11 that has a closed bottom and that, at the end opposite to the respective bottom, is open to allow the insertion therein of the magnetic bodies 17A and 17B. Protruding from the bottom of each containment seat 16 is a rib or a septum 18 that defines and separates two recesses, each of which is adapted to receive a respective magnetic body 17A, 17B.

With reference to figures 3 to 8, each containment seat 16 is then closed by a respective closing cap 19 serving to hold in seat the two magnetic bodies 17A, 17B and to restore the continuity of the surface of the body 11 at which the containment seats 16 open.

The closing cap 19 is made of non-magnetic material, such as a generic thermoplastic.

The closing cap 19 has a rib or septum 20 that projects from the surface thereof adapted to face inwards of the containment seat 16 and that is interposed between the two magnetic bodies 17A and 17B, thus overlapping the rib or septum 18 formed on the bottom of the respective containment seat 16.

The closing cap 19 is removably fixed to the body 11, for example by means of screws 21 that engage in the rib or septum 18.

As mentioned, the body 11 may be variously shaped and not necessarily made as a single body; in particular, the body 11 may be made by coupling at least two separate bodies: an upper body forming the forward guide and a lower body forming the lower guide, which are removably coupled to each other in order to facilitate the maintenance operations and possible replacement of the worn elements.

With particular reference to the embodiment shown in the accompanying figures 3 to 8, the body 11 comprises :

- a base body 22 in which said return guide is formed, and

- a U-shaped body 23 in a single piece that is assembled on said base body 22 and in which the forward guide is formed,

The base body 22 and the U-shaped body 23 are removably coupled to each other and fixed to each other .

The base body 22 and the U-shaped body 23 each define a respective mutual coupling surface 22a, 23a which face one other when the U-shaped body 23 is assembled on the base body 22.

When the U-shaped body 23 is assembled on the base body 22, these respective coupling surfaces 23a, 22a face one other; the coupling surface 23a of the U- shaped body 23 defines the lower surface thereof, while the coupling surface 22a of the base body 22 defines the upper surface thereof.

The U-shaped body 23 is formed in a single piece; that is, it consists of a single inseparable body.

The U-shaped body 23 forms a "U" and defines at least one forward channel 12 in which the hinging portions 102 of the links 101 of the forward branch ΙΟΟΑ are received and at least one pair of forward rails 13 arranged at the sides of the forward channel 12, and each defining a sliding surface 13a for the sliding thereupon of at least one part (wing) of the plate-like portion 103 of the links 101 of the forward branch 100A.

The base body 22 is advantageously also obtained in one piece and also advantageously has the shape of an inverted U defining at least one return channel 14, in which the hinging portions 102 of the links 101 of the return branch 100B are received, and at least one pair of return rails 15 arranged at the sides of the return channel 14, and each defining a sliding surface 15a for the sliding thereupon of at least one part (wing) of the plate-like portion 103 of the links 101 of the return branch 100B.

It is in particular worth noting that the sliding surfaces 15a define the outermost lower surface, that is end surface, of the base body 22 below which the base body 22 does not have any groove or other element that extends continuously along its longitudinal extension to mechanically hold (i.e. by impediment) the links 100 along the return guide. The links 101 of the return branch 100B indeed are held in the respective return guide essentially by magnetic interaction exerted by the pairs of magnets CM.

Preferably, the containment seats 16 of the pairs of magnets CM are formed in the base body 22 so as to be accessible only from the coupling surface 22a of the base body 22 to the U-shaped body 23, that is from the surface of the base body 22 which, in the assembled configuration of the guide 10, defines the upper surface of the base body 22 itself.

Each containment seat 16 indeed is closed on the bottom from the bottom 14a of the return channel 14 and is open at the coupling surface 22a of the base body 22 with the U-shaped body 23.

The respective closing cap 19 is fixed to the base body 22 so as to restore the continuity of its coupling surface 22a.

This configuration of the containment seats 16 facilitates the assembly and disassembly operations of the pairs of magnets CM and therefore, possible maintenance or replacement interventions thereof.

The U-shaped body 23 is coupled to the base body 22 with a male-female type shape coupling free from undercuts and is removably fixed to the base body 22 so as to be assembled and disassembled for possible maintenance or replacement interventions thereof.

The U-shaped body 23 may be fixed to the base body 22 by means of threaded members such as for example, described in EP0903307.

According to an alternative embodiment shown in the accompanying figures 3 to 8, the U-shaped body 23 comprises or is at least partly made of a magnetisable material that is reactive to the magnetic field generated by the pairs of magnets CM to be attracted and held against the base body 22 by magnetic action.

The magnetic attraction between the U-shaped body 23 and the base body 22 is dimensioned so as to resist detachment forces of the U-shaped body 23 from the base body 22 having components orthogonal to the sliding plane defined by the sliding surfaces 13a of predefined entity, so as to ensure the fixing of the U-shaped body 23 to the base body 22 at the usual conditions of use, albeit allowing the detachment by lifting of the first with respect to the second in case of need, such as for example, in the case in which the U-shaped body 23 requires replacing due to wear.

Also in this case, magnetisable material in particular means a ferromagnetic material.

In a preferred embodiment, the U-shaped body 23 comprises at least one hollow seat 24 in which a respective element made of ferromagnetic material is housed, of the type for example, of a plate 25 made of ferromagnetic material. The shape and the sizes of each plate 25 could be different from the ones depicted. For example, the plates 25 could consist of washers or the like.

However, alternative embodiments are not excluded in which the U-shaped body 23 is made of plastic material in which there is dispersed a load of particles made of magnetisable material, in particular ferromagnetic material.

In greater detail and with specific reference to the embodiment shown in the accompanying figures 3 to 8, considering the U-shaped body 23 and the base body 22 in assembly configuration, the one with the plates 25 assembled and the other with the pairs of magnets CM assembled in the respective containment seats 16 closed by the closing caps 19, the two coupling surfaces 23a and 22a are substantially flat and continuous.

The shape coupling between the U-shaped body 23 and the base body 22 is defined by an edge 26 which protrudes from at least the two opposite longitudinal sides of the U-shaped body 23 in a direction substantially orthogonal to the respective coupling surface 23a and that can be inserted in a corresponding seat 27 formed at the two corresponding opposite longitudinal sides of the base body 22.

Preferably, the edge 26 also extends along the two opposite sides of the U-shaped body 23 that extend transversely at the two longitudinal sides thereof. The edge 26 extends along the whole perimeter of the U- shaped body 23; the edge 26 is preferably continuous.

The seat 27 consists of a step and extends along at least the two opposite longitudinal sides of the base body 22 in a direction substantially orthogonal to the respective coupling surface 22a and preferably, also along the two opposite sides of the base body 22 that extend transversely to the two longitudinal sides thereof. The seat 27 extends along the whole perimeter of the base body 22; the seat 27 preferably is continuous .

The edge 26 surrounds the coupling surface 23a of the U-shaped body 23, thus defining a female element.

The seat 27 (step) surrounds the coupling surface 22a of the base body 22, thus defining a male element that can be inserted in the female element defined in the U-shaped body 23.

However, the opposite configuration is not excluded in which the edge is defined in the base body 22 and the respective coupling seat is defined in the U-shaped body 23. The U-shaped body 23 consists of a flat diaphragm from the upper surface of which (i.e. the surface opposite to the coupling surface 23a) two longitudinal edges protrude having rectangular section defining the forward rails 13.

The U-shaped body 23 comprises a plurality of hollow seats 24 open at the coupling surface 23a and closed on the bottom. Each hollow seat 24 houses at least one respective plate 25 made of ferromagnetic material. Advantageously, each plate 25 has a shape complementary to the one of the respective hollow seat 24. The plates 25 are fixed in the respective hollow seats 24 for example, by means of screws that are accessible from the coupling surface 23a or with interference coupling, for example, by interlocking, by gluing or other.

The hollow seats 24 extend at least partly at at least one of the two forward rails 13; preferably, the hollow seats 24 are formed exactly at (below) each forward rail 13. A plurality of hollow seats 24 each housing a plate 25 is distributed in at least one row that extends along the longitudinal extension of the U- shaped body 23 below each forward rail 13.

When the U-shaped body 23 is assembled on the base body 22, the magnetic bodies 17A, 17B of each pair of magnets CM extend below the diaphragm forming the bottom 12a of the forward channel 12 and partly below each forward rail 13.

It is worth noting that only for simplicity of representation, the guide 10 shown in the accompanying figures has a single forward channel 12 and a single return channel 14, the guide 10 according to the present invention being capable of comprising a plurality of forward channels and corresponding return channels, the forward and return rails of respective adjacent forward and return channels being capable of being defined by portions of a same longitudinal edge.

Moreover, alternative embodiments are not excluded of the body 11 defining, in its assembly, the forward guide and the return guide which could be made with different components from the base body 22 and from the U-shaped body 23.

The operation of the guide 10 according to the present invention is immediately comprehensible for those skilled in the art in light of the above description and the accompanying drawings.

It is in particular worth noting that the structure of the guide 10 is particularly simple and compact, thus facilitating and speeding up the assembly and disassembly operations thereof or also only of its worn parts (such as for example, the U-shaped body or the magnetic bodies 17A, 17B) .

The use of pairs of magnets CM as described above, each of which consisting only of a pair of magnetic bodies 17A, 17B of defined height h, which are spaced apart and separated from each other without the use of any ferromagnetic plate for connecting them, provides various advantages:

- it allows reducing the components of the guide and therefore, the relative production and assembly costs with respect to the known solutions that provide the use of two pairs of magnets in which the magnets of each pair are joined by a ferromagnetic plate so as to form a U-shaped magnet;

- it allows simplifying the assembly operations of the pairs of magnets CM, it only being necessary to arrange the magnetic bodies 17A, 17B individually in the respective containment seat 16;

- it allows containing the size in height of the base body 22 or in any case of the body 11 and therefore the production costs thereof, which are strictly correlated with the material necessary for making it.

These advantages are particularly sensible in the case in which each magnetic body 17A, 17B is made in one piece in a single body. Indeed, this latter solution allows decreasing the production costs of the magnetic bodies (magnetic bodies of a wanted height and made in a single piece indeed have lower production costs than the production costs of two or more magnetic bodies each of height equal to a fraction of the height value and coupled in sequence with one another) . Moreover, this solution allows further simplifying the assembly and disassembly operations of the pairs of magnets CM, each of the two magnetic bodies 17A and 17B being capable of being individually handled.

The use of pairs of magnets CM according to the present invention allows obtaining magnetic fields having intensity and distribution such as to ensure an effective holding of the chain both along the forward guide and along the return guide, this latter effect being further amplified by the reduction of the height of the bodies forming the forward and return guides.

Figure 9 schematically shows the lines of the magnetic field generated by a pair of magnets CM according to the present invention, along the forward guide and along the return guide in the absence of the chain 100. It is worth noting a substantially uniform distribution of the field lines.

Figure 10 schematically shows the lines of the magnetic field generated by a pair of magnets CM according to the present invention, along the forward guide and along the return guide in the presence of the chain 100. It is worth noting a substantially uniform distribution of the field lines. The links 101 and in particular their pins 104, close and confine the magnetic field at the forward guide and the return guide .

Figures 9 and 10 refer to a guide as depicted in the accompanying figures 3 to 8 at sections like the ones in figure 7 (in the absence of the plates 25) ; there is an entirely similar distribution in the case in which the U-shaped body is mechanically fixed to the base body, for example with screws, rather than magnetically with ferromagnetic plates (as for example in the embodiment shown in figures 1 and 2) .

Figures 11 and 12 are similar to figures 9 and 10 and schematically show the lines of the magnetic field generated by a pair of magnets CM according to the present invention, along the forward guide and along the return guide in the absence and in the presence of the chain 100, in the case in which the U-shaped body is magnetically held on the base body 22. Also in this case, it is worth noting a substantially uniform distribution of the field lines and in the presence of the chain links, a confinement thereof at the forward and return guides.

If the guide is formed by two bodies - the U- shaped body and the base body magnetically held against each other - the assembly and disassembly operations of the wear parts of the guide are particularly simple and quick; in particular, they do not require the disassembly of the entire guide nor the use of tools.

The main wear part indeed consists of the U-shaped body 23. This U-shaped body 23 is made in a single piece and the plates 25 made of ferromagnetic material are integrally constrained thereto. The U-shaped body 23 is assembled on the respective base body 22 by simply overlapping it to couple therewith: the shape coupling is such as to counter the radial and circumferential forces exerted by the chain conveyor 100 during its motion, while the coupling by magnetic attraction between the U-shaped body 23 and the base body 22 (made by the interaction of the plates 25 with the magnetic field generated by the pairs of magnets CM) is sufficient to avoid the detachment of the first from the second, at the usual conditions of use.

Should it be necessary to disassemble the U-shaped body 23, for example because it is worn, it is sufficient to lift it also only manually by the respective base body 22, thus overcoming the sole force of magnetic attraction generated between the plates 25 and the magnetic bodies 17A, 17B. For such purpose, it is not necessary to disassemble the whole guide 10 and in particular, the base body 22 thereof, the disassembly of the U-shaped body 23 being possible by simply lifting it from the top. Nor is it then necessary to intervene with any tool, for example for loosening any screw, or with other tools or other mechanical actions.

The assembly and the disassembly of the U-shaped body 23 occur without having to disassemble the guide 10 from the conveyor, it being sufficient to move the U-shaped body 23 close to and away from the base body 22 along a direction with component orthogonal to the respective coupling surfaces 22a, 23a.

In that particular case, the magnetic field generated by the pairs of magnets CM - generally provided to interact with the chain in order to hold it in position during its sliding along the guide 10 (by acting on the links themselves or on its articulating pins) - is also used to hold the U-shaped body 23 on the base body 22.

The magnetic guide, in particular the magnetic curved guide, for a chain of a chain conveyor according to the present invention thus conceived is susceptible to several modifications and variations, all falling within the invention; moreover, all the details can be replaced by technically equivalent elements. In practice, the materials used, as well as their dimensions, can be of any type according to technical requirements .