BACKGROUND OF THE INVENTION

The present invention relates to an equipment and the related method for the production of filtering panels.

The field of the invention is that of the production of filtering panels, wherein a fabric of filtering material is tensioned and fixed for moulding inside a frame. The panels of this type are employed in the filtration of municipal and industrial waste water, for the separation of flours, in screen printing and the like.

The methods currently in use for producing the aforementioned filtering panels provide for arranging the filtering fabric, already cut out according to the measurements of the frame which receives it and subsequently fixed on the latter, by manual centering operations among these parts. The preliminary operation of fabric cutting requires in particular the execution of drillings, needed in order to achieve the necessary points of reference for the manual centering of the fabric with respect to the frame, before the moulding of the latter.

The above described operations present however the significant drawback, not only of prolonging the production time of the filtering panels, but also that of increasing the possibility of errors in the manual assembly of the fabric on the frame, with considerable formation of rejects and consequential increase in the costs of manufacturing of the product as a whole.

SUMMARY OF THE INVENTION

The main object of the invention consists in providing a new method and the related equipment for the moulding of filtering panels of the above described type which, compared to the prior art, allow the speed up of the panel production, in a completely automatic way, with no error and with a significant reduction of rejects of the filtering fabric being used.

This and other objects are achieved by the method and the equipment of claims 1 and 5, respectively. Some preferred embodiments of the invention result from the remaining claims.

Compared to the solutions employed in the prior art, the equipment and the method of the invention have the advantage of automating every operation for assembling the filtering panel, locking in position the fabric centered on the frame during the formation, tensioning it and subsequently cutting it from the unwinding roller of the fabric itself.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and characteristics result from the following description of the equipment and the method of the invention illustrated, by way of a non-limiting example, in the figures of the attached drawings.

In them:

- Figure 1 shows in a schematic overall view the equipment of the invention;

- Figure 2 shows the fixed and moving mould halves fitted on the equipment of the invention;

- Figures 3 and 3a show the moving mould half of the equipment of the preceding figures, provided with a sliding mould insert equipped with the matrix for the moulding of the first half frame of the filtering panel;

- Figure 4 shows the fixed mould half of the equipment of the invention, provided with mould inserts respectively for the moulding of the first half frame and for the moulding, on the latter, of the second half frame of the filtering panel;

- Figure 5 shows the detail of the sliding mould insert of the moving mould half of Figure 3;

- Figure 6 shows the detail of the seat for the sliding of the mould insert of Figure 5 in the moving mould half of Figure 3;

- Figure 7 shows the detail of the locking, tensioning and cutting system of the filtering fabric on the sliding mould insert of Figure 3;

- Figure 8 shows the detail of the upper mould insert of the fixed mould half of Figure 4, bearing the matrix for moulding the second half frame of the filtering panel; - Figure 9 shows the detail of the lower mould insert of the fixed mould half of Figure 4, bearing the punch for moulding the first half frame of the filtering panel;

- Figure 10 shows a simplified scheme of the position of the fixed mould half and of the moving mould half in the initial moulding step of the filtering panel;

- Figures 11a and 11 b illustrate the step of moulding the first half frame of the filtering panel;

- Figure 12 shows the positioning of the sliding mould insert of the moving mould half in the moulding step of the second half frame, with tensioning and cutting of the filtering fabric;

- Figure 13 shows the mould halves of Figure 2, with a view to the locking, tensioning and cutting system of the filtering fabric;

- Figures 14 and 15 respectively show in plan view and in side view the filtering panel produced with the equipment and the method of the preceding figures.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The equipment of the invention, referred to as a whole with the numeral 1 in Figure 1 , comprises a frame inside of which the moving mould half 2 and the fixed mould half 3 are mounted. An unwinding roller 4 of the filtering fabric 5 of the panel 8 illustrated in Figures 14 and 15 is furthermore present. The equipment of the invention further includes the press 6 carrying out the injection moulding of the frame 7 of the panel 8.

In Figures 2 and 3 the mould half 2 is shown, movable in the direction of the arrows F1 with respect to the fixed mould half 3, with a view on the mould insert 9, in turn mounted sliding in the direction of the arrows F2 inside its mould insert holder seat or guide 10 in the same mould half 2.

In particular and as better shown in Figure 13, the mould insert 9 slides, by means of the related carriage 20, in the direction of the arrows F2 inside the mould insert holder seat 10 of the moving mould half 2. In the initial step of moulding of the half frame 7a of the panel 8, the mould insert 9 is placed in the lower position 2a of the mould half 2 of the equipment 1 . In the following step of moulding of the half frame 7b, on the half frame 7a already moulded in the preceding step, the mould insert 9 moves from the lower position 2a, wherein the moulding of the half frame 7a has been carried out, towards the upper position 2b of moulding of the half frame 7b of the filtering panel 8.

According to the invention, the mould insert 9 is moreover mounted movable inside its seat 21 in the carriage 20, in the direction of the arrows F3 of Figures 3a and 13, in contrast to the action of springs 18.

As better illustrated in Figure 4, the lower part 3a of the fixed mould half 3 of the equipment 1 of the invention includes a lower mould insert 22 bearing the punch 23 for moulding the first half frame 7a of the panel 8 of Figure 15, in cooperation with the matrix 19 of the mould insert 9 in the position 2a of the mould half 2.

In its upper part 3b the fixed mould half 3 is provided with an upper mould insert 24, bearing the matrix 25 for moulding the second half frame 7b on the half frame 7a moulded at the lower parts 2a and 3a of the mould halves 2 and 3 respectively.

As shown in Figures 5, 7 and 13, the sliding mould insert 9 of the moving mould half 2 has inserts 11a, 11 b, 11c, 11d, preferably made of an elastomeric material, suitable to lock the filtering fabric 5 by cooperation with the corresponding inserts 12a, 12b, 12c and 12d provided on the mould insert 24 of the upper part 3b of the fixed mould half 3.

To the described locking of the fabric 5 also contributes the displacement of the mould insert 9 inward its seat 21 in the carriage 20 supporting it, in contrast to the action of springs 18 biasing it against the upper mould insert 24 of the half frame 3 (arrows F3 in Figures 3a and 13).

On the same mould insert 9 are moreover provided, further inward with respect to the aforementioned inserts 11 and close to the matrix 19 for moulding the half frame 7a, corresponding punches 13a, 13b, 13c and 13d, which carry out the tensioning or the traction of the fabric 5 inside the frame of the panel, when the fabric is locked in the upper part 3b of the mould half 3 between the inserts 12 of the mould insert 24 and the inserts 11 of the mould insert 9. The punches 13 of the mould insert 9 cooperate with the corresponding slots or grooves 14a, 14b, 14c, 14d intended for discharging the same punches 13 in the mould insert 24 of the upper part 3b of the mould half 3, arranged close to the matrix 25 for moulding the half frame 7b.

As better shown in Figures 3a, 7 and 13, on the upper part of the sliding mould insert 9 is moreover provided a blade 15, housed in a corresponding seat 16 positioned above the insert 11a, suitable for cutting the fabric 5 fed by the roller 4, cooperating with a corresponding hollow 17 provided in the mould insert 24 of the upper part 3b of the fixed mould half 3 in Figure 8.

The steps of the method of the invention are better represented in Figures 10 to 12.

In a first step of the method, the mould insert 9 of the moving mould half 2 is placed in the position 2a, at the lower part 3a of the fixed mould half 3 (Figure 10). In this position the moving mould half 2 closes in the direction of the arrow F4 in Figure 11a against the mould insert 22 provided in the part 3a of the fixed mould half 3, with consequent movement of the mould insert 9 back inside its seat 21 in the carriage 20, in contrast to the action of the springs 18 (arrows F5 in Figure 11a).

With the closed mould in this position the injection of the half frame 7a of Figure 15 inside the matrix 19 of the mould insert 9 is carried out, in cooperation with the punch 23 provided on the aforementioned mould insert 22 (Figures 3, 11a and 11b).

In the subsequent step the moving mould half 2 moves away from the fixed mould half 3, leaving on the matrix 19 of the mould insert 9 the half frame 7a moulded as above described.

From this position, the mould insert 9 is made to slide by the carriage 20 in the direction of the arrow F6 in Figure 11 b, towards the upper position 2b of the mould half 2, until it reaches the height of the part 3b of the mould half 3 (Figures 11 b and 12). In this position the fabric 5 is unwound from the roller 4, in order to position it between the mould insert 9 and the upper mould insert 24 facing each other.

At this point the moving mould half 2 closes on the fixed mould half 3 in the direction of the arrow F7 in Figure 12, with the return of the mould insert 9 inside its seat 21 of the carriage 20 of the moving mould half 2 (arrow F8).

In this step the following operations are carried out in an automatic way:

- the locking in position of the filtering fabric 5 on the previously formed half frame 7a, by interference of the inserts 11 of the mould insert 9 of the mould half 2 with the inserts 12 of the upper mould insert 24 of the mould half 3;

- the tensioning of fabric 5, in a centered position with respect to the half frame 7a housed in the moving mould insert 9, by insertion of the punches 13 of the same mould insert 9 inside the grooves 14 of the mould insert 24, with the dragging of a corresponding portion of fabric 5 inside these grooves and consequent tensioning of the fabric itself;

- the moulding of the half frame 7b on the half frame 7a, so as to form the frame 7 of the filtering panel 8.

Then the fabric 5 is cut in its upper part by the blade 15, thus releasing it from the feeding roller 4.

The opening of the mould then leaves the filtering fabric 5, tensioned and fixed in a perfectly centered way on the frame 7, with some fabric portions in excess, protruding to the outside of the same frame and which may be easily removed in order to give the panel 9 the structure represented in Figure 14.

The method of moulding the panel of the invention is preferably carried out at a temperature of 200-300°C and at a holding pressure of the press in the moulding steps of two half frames of 25-50 bar, as well as at a conditioning temperature of the same mould of 20-60°C.

To the invention, as described above and illustrated in the Figures, it is possible to make some modifications in order to realize some variants which however are included in the scope of the following claims. Thus, for example, the material for the manufacturing of the frame 7 of the panel 8 may be any thermoplastic polymer, either reinforced or not, suitable for the injection moulding and preferably suitable for medical and food usage. On the other hand, the manufacturing material of the fabric 5 may consist in a polyamide, polyethers and the like.