PRIOR ART Filter presses used in various industrial sectors are known, comprising a plurality of movable vertical plates aligned along a horizontal axis.

Said plates lie between a fixed headpiece and a movable headpiece, and can be clamped together to define a plurality of filtration chambers.

Each plate comprises two recesses in the two opposing faces, to define a chamber between two mutually contacting plates, with which a filter cloth is associated at each recess to separate the solid part from the liquid part of the fluid or semifluid material to be filtered.

Said cloths substantially divide each chamber into a first region connected to an entry channel for the material to be filtered, and where said solid part accumulates, and a second region into which the filtered liquid passes, and which is connected for its evacuation to a channel provided within the body of the plates.

The entry channel for the material to be filtered comprises a conduit of circular cross-section inserted into a hole the walls of which are provided in two matching semicylindrical half-cavities present in one side of each plate.

When the plates are clamped together the channel hence lies inserted

into said hole together with the filter cloths associated with each plate.

The filter cloth is hence compressed into the semicylindrical half-cavities by the channel, so undergoing rapid wear, particularly at the sharp edge which forms between each half-cavity and the plane in which the contacting plates are joined together. This causes premature tearing of the cloths, which hence have to be replaced with a certain frequency.

The object of the present invention is to overcome the drawbacks of the known art within the framework of a simple, rational and reliable solution.

DISCLOSURE OF THE INVENTION The invention attains said object by virtue of the characteristics defined in the claims.

In particular, the invention provides a feed device for a filter press provided with at least two plates to be clamped together to define a filtration chamber, usual filter cloths being interposed therebetween. The device of the invention comprises a portion to be inserted between two half-cavities, each of which is present in one side of said at least two plates and presents a profile matching the outline of said portion. The outline of that portion of the device to be received in said half-cavities is such that the tangents thereto at the plane in which said plates are joined together form an angle less than 180 degrees. Preferably said angle is between 40 and 80 degrees.

According to the invention the length of that portion to be inserted between said plate half-cavities is a function of the material to be filtered.

In certain applications said portion can be as long as one side of the plate.

Such a configuration offers the advantage of ensuring complete filling of

the chamber and homogeneous distribution of the material within it, while requiring much shorter chamber filling times which shorten the productive cycle.

DETAILED DESCRIPTION OF THE DRAWINGS The constructional and functional characteristics of the invention will be more apparent from the ensuing description of two preferred embodiments thereof given by way of non-limiting example and shown in the accompanying drawings.

Figure 1 is a perspective view of the device according to the invention.

Figure 2 is a partial section through the device of the invention positioned between two spaced-apart plates.

Figure 3 is the same as Figure 2 but with the plates closed.

Figures 4,5 and 6 show some variants of the invention.

Figure 7 is a perspective view of a second embodiment of the device according to the invention.

Figure 8 is an enlarged partial view of Figure 7.

Figure 9 shows the section IX-IX of Figure 7.

Figure 10 shows the section IX-IX in a different operative stage.

BEST MODE FOR CARRYING OUT THE INVENTION Figures from 1 to 6 show the feed device 1, comprising a rear header 2, which at one end is connected to the delivery port feeding the material to be filtered, and at the opposite end communicates with three feed holes 3 for the material. The holes 3 are provided in a portion 4 of the device 1 which is of elongate hexagonal shape in cross-section and branches from

said header 2.

In other embodiments of the invention the number and shape of said holes can be different depending on the type of material to be filtered.

The portion 4 of the device 1 is inserted between two matching half- cavities 5, each of which is provided in one side of a plate 6. Each plate 6, of known type, presents two inner recesses 60 in opposing faces, to define a chamber 61 between two mutually contacting plates. With each recess 60 there is associated a filter cloth 7 for separating the solid part from the liquid part of the fluid or semifluid material to be filtered.

With reference to Figure 3, it can be seen that when the plates are clamped together, the portion 4 of the device is received between the two half-cavities 5, with the cloths 7 interposed. As the angle a formed by the tangents to the profiles of the portion 4 at the plane in which the plates 6 are joined together is less than 180°, the cloths do not rest on sharp edges as in the known art, and are therefore not subjected to wear.

Figures 4,5 and 6 show some variants of the portion 4 of the feed device. which in cross-section present a rhombus shape 40 or comprise two arcuate profiles 41 joined together at their ends. In both cases the angle a formed by the tangents to the profiles of the portion 4 at the plane in which the plates 6 are joined together is less than 180°. In addition, instead of the holes 2 the variants shown in Figures 5 and 6 have a single elongate slot 42.

Figures from 7 to 10 relate to a second embodiment of the invention, which is described hereinafter, noting that in the description of said second embodiment, components identical to those already described in the first embodiment of the invention are indicated by the same reference

numerals.

Said figures 7,8, 9 and 10 show the feed device 10, comprising an elongate portion 11, which is of elongate hexagonal shape in cross- section and is intended to be received in two matching half-cavities 12, each of which is provided in one side of a plate 13. Each plate 13, of known type, is substantially similar to the already described plate 6 and presents two inner recesses 60 in opposing faces, to define a chamber 61 between two mutually contacting plates. With each recess 60 there is associated a filter cloth 7 for separating the solid part from the liquid part of the fluid or semifluid material to be filtered.

The portion 11 is at least as long as a side of the plates 13 and collaborates to constitute, when the plates 13 are clamped together, the upper side of said chamber 61 (Figure 10). Internally, the portion 11 is provided with a central header conduit 110 the purpose of which is to feed the material to be filtered to a plurality of equidistant branches 111, which open at the lower edge of the portion 11.

Said header conduit 110 is connected to a pump, not shown, for feeding the material to be filtered.

The branches 111 distributed along the portion 11 advantageously ensure a uniform distribution of the material to be filtered within the chamber, and hence the complete and rapid filling of the chamber.

With reference to Figures 9 and 10, it can be seen that when the plates are clamped together, the portion 11 of the device is received in the two half-cavities 12, with cloths 7 interposed. As the angle a formed by the tangents to the cross-section through the portion 11 at the plane in which the plates 13 are joined together is less than 180°, the cloths do not rest

on sharp edges as in the known art, and are therefore not subjected to wear.

In the illustrated embodiment the portion 11 is of hexagonal cross-section, however in other embodiments the portion 11 can have any shape suitable for the purpose, for example a lozenge or rhombus shape, or can consist of two arcuate profiles joined together at their ends.