Technical Field

The present invention relates to an ejector assembly for a mold of a press for manufacturing a ceramic article.

Background Art

The presses for the manufacture of ceramic articles of known type are provided with one or more molding seats, delimited at the bottom by a mold and at the top by a punch, inside which the ceramic article is formed.

At the end of the molding process, the ceramic article thus formed is expelled and sent to the following machining phases.

The molds generally used today comprise a fixed portion, which is associated with the structure of the relevant press, and a movable portion which is used to expel the ceramic article at the end of the molding thereof.

The press is then provided with an ejector assembly, adapted to move the movable portion, comprising a plurality of jacks anchored on one side to the fixed portion of the mold and on the other side to the movable portion.

In particular, each jack has a relevant cylinder associated with the fixed portion of the mold and a relevant stem, which can be moved along a longitudinal axis, associated with the movable portion of the same.

The operation of the jacks causes the displacement of the movable portion between an operating position, wherein the ceramic article is molded, and an ejection position, wherein the movable portion is raised and the ceramic article is ejected to be sent to the following machining phases.

In order for the mold plate to be raised by keeping horizontally, the fluid- operated jacks must be operated in such a way that they move substantially simultaneously and with equal displacements.

The ejector assemblies of the known type may comprise jacks that are either fluid- operated or electrically-operated.

In the first case, it is difficult to obtain the simultaneous movement and with equal displacements, because if one jack finds greater resistance than the others, this jack remains behind, thus causing the inclination of the ejection plate with the risk the same will jam. To solve these drawbacks, devices have been proposed to correct the operation of the jacks, which, on the one hand, are not always able to completely correct the time and place displacement between the jacks and, on the other hand, make the operation system of the jacks more complicated and delicate. The difficulty in controlling the operation of the jacks of the mold is even greater in the case of large-sized molds, e.g. for the manufacture of tiles with at least one of the sides measuring one meter or more. In the second case, each jack is provided with a relevant electric motor, which allows precisely controlling both the displacement timing and the extent of each jack.

This solution is described by patent WO2015181646.

Also this second solution has however some drawbacks, since it does not allow exerting high power, because of the use of electric motors. It is also economically more expensive than using fluid- operated jacks, both because of the manufacturing cost of jacks provided with electric motors and because the latter must be independently powered.

Description of the Invention

The main aim of the present invention is to devise an ejector assembly that allows overcoming the limits of the solutions known today, that is, that allows exerting high power on the movable portion of the mold and at the same time to control the displacements in a precise and synchronized manner.

Within this aim, one object of the present invention is to devise a solution which is constructively simple and cost effective.

Another object of the present invention is to devise an ejector assembly for a mold of a press for manufacturing a ceramic article that allows overcoming the aforementioned drawbacks of the prior art in a simple, rational, easy, effective to use and low cost solution.

The aforementioned objects are achieved by the present ejector assembly for a mold of a press for manufacturing a ceramic article.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become more evident from the description of a preferred but not exclusive embodiment of an ejector assembly for a mold of a press for manufacturing a ceramic article, illustrated by way of an indicative yet non-limiting example in the accompanying tables of drawings in which:

Figure 1 is an axonometric view of an ejector assembly according to the invention;

Figure 2 is a side elevation view of a jack of the ejector assembly in Figure 1. Embodiments of the Invention

With particular reference to these figures, reference numeral 1 has been used to indicate an ejector assembly for a mold of a press (not illustrated in the figures) for manufacturing a ceramic article, such as tiles and the like.

The ejector assembly 1 comprises a fixed plate in use, identified in the figures with reference numeral 2 and a plurality of jacks 3, each of which comprises a relevant fixed cylinder 4, associated with the fixed plate 2, and a stem 5, which can be moved along a longitudinal axis X and connected to the movable part of the mold which is intended to eject the ceramic article after having been made in the mold itself. The stem 5 of each jack 3 can be moved independently of the others.

More specifically, the cylinder 4 of each jack 3 is housed in the plate 2 in a relevant seat 6.

The stem 5 of each jack 3 is provided with relevant connection means, not visible in detail in the figures, to the movable part of the mold.

Appropriately, the jacks 3 are equally distributed with respect to the surface of the mold.

In the embodiment shown in Figure 1, there are four jacks 3, but the technician in the field can easily appreciate that the number of jacks 3 may be any.

According to the invention, each jack 3 comprises feeding means 7 of a work fluid, adapted to move the relevant stem 5 along the longitudinal axis X, at least one proportioning valve 8 operatively connected to the feeding means 7 and detection means 9 for detecting the position of the stem itself operatively connected to the proportioning valve 8. The proportioning valve 8 of each jack 3 is connected to a circuit 10 under pressure of the work fluid.

Appropriately, the circuit 10 is connectable in a fluid- operated manner to the fluid- operated system of the press adapted to move the relevant punch for molding the ceramic article.

More in detail, each of the jacks 3 has two chambers, arranged on opposite sides of the relevant stem 5 and not visible in detail in the figures, and the feeding means 7 comprise relevant feeding lines 7a of each chamber, both connected to the relevant proportioning valve 8. In the embodiment shown in the figures, only one feeding line 7a is visible, as the other is formed directly inside the proportioning valve 8.

Preferably, the detection means 9 are of the type of a linear transducer associated with the relevant stem 5.

More particularly, as the technician in the sector knows, the proportioning valve 8 is adapted to intervene on the feeding means 7 to vary the flow rate of the work fluid entering and leaving the chambers of the relevant jack, in such a way as to adjust the displacement of the relevant stem 5.

Advantageously, the ejector assembly 1 comprises at least one control and command unit 11 operatively connected to the detection means 9 and to the proportioning valve 8 of each jack 3. The control and command unit 11, e.g. of the type of an electronic control unit, is adapted to operate the proportioning valve 8 of each jack 3 to adjust the flow rate of the work fluid according to the position detected by the detection means 9.

In other words, according to the detected position of the stem 5, the relevant proportioning valve 8 adjusts the feeding of the work fluid to the relevant jack 3 in such a way that the movement of the stem itself takes place according to predetermined displacement heights and speeds.

In general, through the control and command unit 11 and the relevant proportioning valve 8, the stem 5 of each jack 3 is able to move completely independently in terms of position, peak speed, displacement dynamics, acceleration ramps and intervention times according to predetermined operating modes.

In an embodiment of the ejector assembly according to the invention, the control and command unit 11 is adapted to operate on the proportioning valve 8 of each of the jacks 3 in order to operate the relevant stems 5 with displacement heights substantially equal to each other and in a substantially simultaneous manner, so that the plate of the mold is kept substantially horizontal.

In an alternative embodiment, the control and command unit 11 is adapted to operate the proportioning valve 8 of each jack 3 in order to operate the relevant stems 5 with different displacement heights and speeds, e.g. to compensate for variations in the behavior of the mold loading carriage, which may result from ageing, wear, or different properties of the soil used, in order to obtain a product with uniform characteristics after pressing.

In the event of unevenness or asymmetries in the distribution of soft soil in the mold, or defects in the tile after pressing, the control and command unit 11 can modify the displacement and the speed of each stem 5 in order to correct such defects and reduce production waste.

It has in practice been ascertained that the described invention achieves the intended objects and, in particular, it is underlined that the ejector assembly to which the present invention relates is characterized both by high power output and high precision of displacement.

This is due in particular to the simultaneous use of a proportioning valve adapted to manage the flow of a work fluid into the relevant jacks, and of a linear transducer adapted to detect the position of the stem and to send a retroactive signal to the proportioning valve that adjusts the stem displacement accordingly.

The use of fluid- operated jacks also makes it easier to feed them, as it allows the fluid- operated system of the relevant press to be exploited, thus also resulting of lower costs compared to known solutions.