"A PRESSING UNIT FOR A PRESS FOR THE PRODUCTION OF

PRODUCTS, IN PARTICULAR CERAMIC PRODUCTS". Designated inventors: Vito Perrone, Antonio D'Aulerio

TECHNICAL FIELD OF THE INVENTION

The present invention regards a pressing unit for a press for the production of products, in particular a pressing unit for a press for the production of ceramic products, e.g. ceramic tiles or plates.

STATE OF THE PRIOR ART

The pressing units for the presses for ceramic products proposed up to now usually comprise one or more actuators with pistons, usually circular and intended to move the movable cross member or the half-mold.

If large-size tiles or plates must be pressed, or for simultaneously pressing multiple tiles, in order to develop the necessary thrust force one must use very large actuators; this, as will be understood, involves a high energy consumption, along with considerable production costs.

In addition, the thrust that is obtained from a single actuator with cylindrical shape is not well distributed on a pressing unit with rectangular shape, more or less elongated, since the ends of the rectangle are not covered by the thrust surface of the cylinder.

Hence the pressing unit must be constructed with a head and a movable cross member of large thickness in order to obtain a sufficient rigidity of the assembly, but this involves an increase of the weight and production costs.

Alternatively, a plurality of smaller actuators can be used, or in any case actuators with size smaller than that necessary with the use of a single actuator; such actuators must be arranged side-by-side and they must simultaneously actuate the movable cross member of the pressing unit, however the plan surface available in the pressing unit for the smaller cylindrical actuators might not be sufficient to allow the aforesaid actuators to develop a sufficient thrust force for the required objects.

In order to better exploit the space available in the pressing unit in plan view, it could be thought to use only one actuator with an oval plunger or with a plunger of another similar geometry in a manner so as to use the most thrust surface available in the pressing unit in plan view, but in such case problems could arise in the actuator itself, in particular problems of seal of the actuator gaskets. Indeed, the sections of the wall of the cavity in which the plunger of the actuator slides - such sections with greater radius of curvature would be subjected to forces (e.g. bending) that are greater than the sections with smaller radius of curvature, which would determine a localized deformation that would prevent a good seal between the plunger and the wall of the actuator. In addition, also the construction of actuators with oval plungers or with plungers of another complex geometry is very costly.

OBJECTS OF THE INVENTION

One object of the present invention is therefore to provide a pressing unit for a press for the production of products, in particular ceramic products, of improved type.

Another object of the present invention is to provide a pressing unit for a press for ceramic products which ensures a good distribution of the thrust force on the surface available in the head and in the movable cross member of the pressing unit.

Still another object of the present invention is to provide a pressing unit for a press as indicated above which ensures a good thrust force even with limited bulk.

A further object of the present invention is to provide a pressing unit as indicated above which ensures a good fluid seal, along with a structure such to preserve the integrity of the sealing means or seal.

Another object of the present invention is to provide a pressing unit that is simple and inexpensive to obtain and assemble.

In accordance with one aspect of the invention, a pressing unit according to claim 1 is provided.

The dependent claims refer to preferred and advantageous embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will be clearer from the description of one embodiment of a pressing unit, illustrated as an example in the drawing set in which:

figure 1 is a plan view with transparent parts of the pressing unit according to the present invention;

figure 2 is a section view along the line II-II of Fig. 1 ;

figure 3 is a view of a detail in enlarged scale of Fig. 2;

figure 4 is a section view of a detail of the pressing unit of Fig. 1 ;

figure 5 is a section view along the line V-V of Fig. 1 , but in which a part of the pressing unit is in rest position and the other is in thrust position;

figure 6 is a section view of the first component of the pressing unit with parts removed for improved comprehension; and

figure 7 is a section view of the second component of the pressing unit with parts removed for improved comprehension.

In the set of drawings, equivalent parts or components are marked by the same reference numbers.

EMBODIMENTS OF THE INVENTION

With reference to figures 1 to 7, a pressing unit 1 is illustrated for a press (not shown) for the production of products, such as ceramic products, e.g. in particular large-size tiles or plates.

The pressing unit 1 according to the present invention essentially comprises a first fixed component or head 2 and a second movable component or cross member 3, connected and inserted in a press for ceramic products (not illustrated) according to known modes which are not the subject-matter of the present invention.

The pressing unit 1 also comprises actuation means including at least two fluid actuators 4a, 4b, 5, i.e. at least one first actuator 4a, 4b and at least one second actuator 5; such actuators 4a, 4b and 5 are arranged adjacent, partially overlapped in plan view and vertically offset. This signifies that the or each first actuator 4a, 4b is situated at a distance from a pressing face 3b (which will be better discussed hereinbelow) greater than the or each second actuator 5 and in addition that the thrust area of the or of each first actuator 4a, 4b is partially (but not entirely) overlapped on the thrust area of the or of each second actuator 5 along the pressing direction A-A. According to one version of the present invention, all the actuators 4a, 4b, 5 have cylindrical shape.

In the embodiment illustrated in the figures, the pressing unit 1 comprises three actuators 4a, 4b and 5, two first actuators or side actuators 4a, 4b and one second actuator or middle or central actuator 5, the side actuators 4a, 4b being arranged on opposite sides from each other with respect to the central actuator 5. The central actuator 5 is situated in a different plane, e.g. lower plane, with respect to the two side actuators 4a and 4b, which can be substantially aligned or in a same plane.

In addition, the two side actuators 4, 4a are arranged with the respective cavity or cylinder 6a delimited by the head 2 and by the top of the plunger 3e, the plunger 3e being in turn connected to the cross member 3, while the central actuator 5 has a plunger 2e connected to the head 2 and the respective cavity or cylinder 6b delimited by the cross member 3 and by the top of the plunger 2e itself.

The overturned arrangement of the central actuator 5 with respect to the side actuators 4a, 4b allows an optimal use of the space available in the pressing unit 1 , while the partially overlapped arrangement in plan view allows having a greater thrust surface than that which would be obtained with a simple side-by- side arrangement of the actuators.

The actuators can have the same dimensions as well as symmetry axes aligned in a same plane w-w, if desired vertical, in which the pressing direction A- A lies. Naturally, it must be noted that all the actuators could also be overturned, i.e. the side actuators 4a, 4b could have the plungers connected to the head 2, while the cylinders connected to or delimited by the cross member 3, along with the central actuator 5, could have the plunger connected to the cross member 3 and the cylinder connected to or delimited by the head 2.

In addition, there could be any number of actuators, starting from two actuators, i.e. at least one first actuator 4a, 4b and at least one second actuator 5.

For example, as a function of the geometric shape and the surface available in the pressing unit, there may be four, five or six cylindrical actuators partially overlapped and arranged according to a quadrilateral, a pentagon, a hexagon etc..

The head 2 then comprises a first internal face 2a, composed of the set of bottoms of the cylinders 6a and by the top of the central plunger 2e, while the movable cross member 3 has a second internal face 3a directed towards the head 2, composed of the set of tops of the two lateral plungers 3e and by the bottom of the central cylinder 6b, such second internal face 3a being complementary to the first internal face 2a of the head 2.

The cross member 3 further comprises a pressing free face 3b directed towards the products, if desired substantially flat and horizontal. The cross member 3 is also slidably or movably mounted with respect to the head 2.

The pressing unit 1 is applied above or facing a bed RS (figure 5) for supporting products (not shown) to be treated/pressed, for example above a conveyor belt (not shown) or the lower part of a mold (not shown), in a manner such that between the bed RS and the pressing free face 3b of the pressing unit 1 , a pressing area PZ remains delimited.

The actuation means operate on the second internal face 3a in a manner so as to move the movable cross member 3 along a pressing direction A-A substantially transverse or orthogonal to the pressing free face 3b, between a first rest position and one or more second thrust positions, in which the movable cross member 3 is moved with respect to the head 2 in a manner such to move the pressing free face 3b away from the latter. The pressing direction A-A can for example be vertical.

The actuation means can for example be of oleo-dynamic, hydraulic or pneumatic type.

If the actuation means are of oleo-dynamic, hydraulic or pneumatic type, the pressing unit can also comprise at least one conveying duct CCa, CCb, CCc, three according to the embodiment in the figures, which or each of which is extended within the head 2 (according to the example illustrated in the figures) or within the cross member 3 and leads to or operates in the cylinders 6a, 6b of the actuators 4a, 4b, 5, thus pressing on the second internal face 3a. Due to such structure, when an actuation fluid is fed, for example an oil, inside the conveying ducts CCa, CCb, CCc, the latter (i.e. the actuation fluid) presses against the second internal face 3a, in a manner such that the cross member 3 is moved with respect to the head 2 along a pressing direction A-A that is substantially transverse or orthogonal to the pressing free face 3b, between a first rest position (see figure 2 and the left part of figure 5), in which the head 2 and the cross member 3 are adjacent or in abutment at the first 2a and second 3a internal face, and a second thrust position (see the right part of figure 5), in which the cross member 3 is moved so as to move the pressing face 3b away from the head 2.

With regard to the vertical displacement of the actuators 4a, 4b, 5, the second internal face 3a comprises a first surface or section 35 situated at a distance from the pressing face 3b greater than a second surface 36, therefore the first surface or surfaces 35 and the second surface or surfaces 36 are substantially offset or at different levels along an axis parallel to the thrust direction A-A.

Then, with regard to the partial overlapping in plan view of the actuators

4a, 4b, 5, it can be observed (figures 6 and 7) that each actuator has a portion 25a- 35a, 26a-36a, definable as main portion, as well as at least one portion 25b-35b, 26b-36b, definable as overlapped portion.

Consequently, also each plunger 2e, 3e of the actuators 4a, 4b, 5 has a main portion 26a, 35a, as well as at least one overlapped portion 26b, 35b. The overlapped portion 25b-35b of one or each first actuator 4a, 4b and the overlapped portion 26b-36b of one or each second actuator 5 are extended around a same first axis x-x that is substantially central with respect to the overlapped portions and parallel to the pressing direction A-A.

If desired, the overlapped portion 25b-35b of a first actuator 4a, 4b is substantially aligned with the overlapped portion 26b-36b of a second actuator 5 along said pressing direction A-A.

The main portions 25a-35a and 26a-36a are extended around respective second y-y and third z-z axes, substantially central with respect to the aforesaid main portions and parallel to the pressing direction A-A, as well as arranged at a certain distance from each other and at a certain distance from the first axis x-x.

In order to decrease the bulk of the pressing unit 1 in vertical direction, the first cylinders 6a and the second cylinders 6b are directly obtained respectively in the head 2 and in the movable cross member 3.

Hence, each first cylinder 6a is mainly delimited by a respective first surface 25 of the head 2, while the or each second cylinder 6b is mainly delimited by a respective second surface 36 of the cross member 3.

In addition, each first cylinder 6a is also delimited by a respective first surface 35, i.e. by the top of the plunger 3e, and the or each second cylinder 6b is also delimited by a respective second surface 26, i.e. by the top of the plunger 2e.

More particularly, the head 2 comprises a first plate portion 2c in which the first cylinders 6a are obtained with a second wall 2d and, if desired a lateral wall 2g, such walls 2g and 2d rising from the first plate portion.

The lateral wall 2d also constitutes one or more support portions, i.e. a stem or multiple stems, for the first plunger(s) 2e.

The first plunger(s) 2e have a diameter greater than the stem(s) 2d and hence have at least one first internal chamfer 2f directed towards the first portion 2c.

The cross member 3 comprises a first plate part 3c externally defining the pressing free face 3b and at least one second part 3d rising from the first plate part 3c which constitutes a stem, or multiple stems if provided, for at least one second plunger 3e.

Also the second plunger(s) 3e have a diameter greater than the stem(s) with respect to the stem(s) 3d and hence have at least one second chamfer 3f internally directed towards the first part 3c.

With one such structure, the or each second plunger 3e is slidably mounted in a respective cylinder 6a, between a first rest position and a second thrust position, in which the first chamfer 2f faces the second chamfer 3f.

The chamfers 2f, 3f can have a simple wall with tilted plane, or have an optimized shape so as to obtain an improved rigidity of the cantilevered part of the plungers 2e, 3e.

The or each first cylinder 6a is delimited between a first surface 25, i.e. the respective bottom of the cylinder, a first surface 35, i.e. the respective top of the plunger, and the respective cylindrical lateral wall.

The or each second cylinder 6b is delimited between a second surface 26, i.e. the respective top of the plunger, a second surface 36, i.e. the respective bottom of the cylinder, and the respective cylindrical lateral wall.

The plungers 2e, 3e of a pressing unit according to the present invention can all be equivalent and have beveled or removed lateral portions 2f, 3f.

In order to be able to have all the plungers 2e. 3e substantially equivalent, two beveled or removed portions are present in the central plunger(s) 2e, one at each side actuator 4a, 4b, and also the lateral plungers 3e have two beveled or removed parts, even if only one beveled or removed portion at a respective actuator 4a, 4b would be sufficient.

In substance, a pressing unit according to the present invention comprises at least two areas of thrusting (each area being situated at a first actuator 4a, 4b or second actuator 5), preferably cylindrical, by the actuation means on the cross member 3, such areas being offset along an axis parallel to the pressing direction A-A; furthermore, such areas are partially offset also orthogonally or transversely with respect to the thrust direction A-A, but with partial overlapping, such that the action of the actuation means on one of the thrust areas is added to the action of the actuation means on the other of the thrust areas.

The actuation means are instead constituted by two or more oleo-dynamic, hydraulic or pneumatic actuators, each acting or pressing in a respective thrust area.

In order to be able to mount the pressing unit 1 , the head 2 is formed by two or more elements connected with each other, e.g. a first element comprising the first plate portion 2c and the lateral wall 2d and a second element comprising the first plunger 2e, such second element being constrained to the first element for example by means of screws, bolts 8 or similar means.

Still for mounting purposes, also the cross member 3 is formed by two or more elements connected to each other, for example a first element comprising the first plate part 3c and a respective stem 3d and a second element comprising the second plungers 3e as well as constrained to the first element for example by means of screws, bolts 10 or similar means.

Also provided in the plungers 2e, 3e are the sealing means 1 1a, l i b, 1 1c; the sealing means are intended to prevent leakage of the actuation fluid.

More particularly, the sealing means can comprise one or more scraper components 1 la, one or more sealing gaskets 1 lb, one or more guide components l ie.

In addition, drainage means can be provided 12 for draining the fluid conveyed into the chambers 6a, 6b. For such purpose, the drainage means 12 comprise a duct in fluid communication with a gap arranged between the head 2 and the cross member 3 and delimited between two respective annular sealing elements 1 1a, l ib.

The pressing unit 1 according to the present invention further comprises means 13 for moving the cross member 3 from the or from a second thrust position to the first rest position, since in the illustrated example the actuators 4a, 4b and 5 are of single-acting type.

It must in any case be observed that, according to the present invention, the actuators 4a, 4b and 5 could also be of double-acting type.

Hence, the pressing unit 1 can be provided with auxiliary actuators, for example oleo-dynamic, hydraulic or electrical, intended to bring the movable cross member 3 back to the rest position.

In such case, the cylinder 13a of the auxiliary actuator can be mounted in or constrained to the head 2 and have a stem 13b or the like kinematically connected to the cross member 3.

The cross member 3 can have eyelet elements 3h projecting, for example laterally, in which one end is mounted or articulated of a stem or a respective stem 13b that is slidably mounted in the or actuated by the cylinder 13a.

In addition to the return function of the movable cross member 3, the auxiliary actuators 13 can also perform the function of ensuring the movement of the cross member into correct position, i.e. by maintaining the pressing free face 3b substantially orthogonal to the provided pressing direction A-A.

In such case, the auxiliary actuators 13 are of double-acting type and position transducers 14 are also provided that are intended to detect, at every instant, the position of the cross member 3.

For example, considering figure 5, if during the pressing movement the cross member 3 has the left part higher than the right part, a control device (not shown) detects such movement difference by means of the position transducers 14 positioned to the right and left.

After this, the control device sends an actuation command towards the bottom of the actuator or actuators 13 on the left, so as to provide a further thrust to the left and correct the movement error of the cross member 3.

The pressing unit can also be provided with means 15 for guiding the movement of the cross member 3 with respect to the head 2, e.g. a channel in the head 2 in which a rod is slidably mounted that is constrained to the cross member 3 or vice versa.

As will be understood, due to a pressing unit according to the present invention, it is possible to use actuators (in the above-indicated sense) also with limited size, which are suitably arranged so as to obtain a partial overlapping of the thrust areas along the pressing direction, which considerably limits, in particular if the actuators are substantially cylindrical or in any case the actuation means operate on substantially circular surfaces, the extension of the free areas FA between one part and the other of the internal face of the cross member 3, i.e. the areas not affected by the actuation means.

Due to this, it is possible to obtain a sufficient thrust on the cross member with small or less powerful actuation means, or, where large or powerful actuation means are used, obtain a much greater thrust or pressing force with respect to the presses proposed up to now.

This can be understood with reference to figure 1 , which illustrates the pressing unit 1 in plan view and shows substantially circular actuators 4a, 4b and 5 that have overlapping areas SZ along the pressing direction.

It will be observed that due to such expedient, in combination with the vertical displacement of the actuators, it is possible to limit the aforesaid free areas FA.

Modifications and variants of the invention are possible within the protective scope defined by the claims.