An improved structure for a press, in particular for moulding ceramic products

Abstract: An improved structure for a press, in particular for moulding ceramic products, comprising a resistance structure constituted by a plurality of resistance elements (1), arranged side-by-side and aligned consecutively a predetermined reciprocal distances, each of which resistance elements (1) is composed of an annular element (2) internally of which two segments (3) are housed in diametrically opposite positions, which two segments (3) exhibit a first portion (30) of edges thereof which are shaped so as to couple with a correspondingly shaped portion of the inner edges of the annular element (2) and a second portion (31) which is opposite to the first portion (30). The second portions (31) face one another and are maintained at a distance one from another in order that a chamber is identified there-between internally of which at least one power tool (5) destined to exert a pressing action can be housed. The second portions (31) are maintained at a distance one from another by two spacer devices (14) which are at two diametrically opposite tracts of each annular element (2). Each spacer device (14) comprises at least one parallelepiped spacer (4) and at least one wedge (15) predisposed to combine with the spacer (4).

Description: The field of use of this invention is very wide and certainly comprises all of the possible applications in which moulding or plastic deformation by pressing are involved, preferably by vertically-applied force. Specifically, though not exclusively, the invention is usefully applied in moulding ceramic products, in particular tiles. The prior art comprises vertical hydraulic presses for forming ceramic tiles which exhibits a structure or frame uniting the moving and the fixed parts and which must be especially rigid and, in the example, is typically a closed frame with two uprights, access to which is possible on either opposite side. There is generally a very wide (indeed, the widest possible) free space between the two uprights or columns which is used to infeed and outfeed the material under formation. The size of this space is decided on the basis of the largest usable and pressable rectangle which can be obtained - the rectangle being the plane on which the pressing takes place. The pressing action is necessarily discontinuous and intermittent. The fact of having a wide-as-possible space which is necessarily greater than the depth is in large part due to the need to render as short as possible the run a powder-loading truck has to make in order not to penalise the production rhythm. In the prior art, the considerable space between the two uprights means that the most massive parts of the press are developed in a perpendicular plane to the infeed direction of the powders to be moulded. The overall structure is therefore rather tall and wide - in some cases a partial interment of the press is required in order to give it the necessary stability. The height of these structures is mostly due to specifications of the traditional constructional techniques, where a base and an upper crossbar (linked by the uprights) are both present and have to be very thick - in a vertical direction - in order to guarantee a very high resistance to deformation to the two planes which absorb the application of the pressing forces, i.e. the planes on which the bottom and top dies of the mould operate. By way of example, in hydraulic presses used for forming ceramic tiles, which presses are liable to exert a pressing force of up to 7,000 tonnes and which have a free space between the uprights of more than 2 metres, the whole structure can be above 7 metres high, and can be buried by up to a third. In consideration of the forces in play, in order to guarantee these known structures sufficient indeformability so that they can cope with any possible defects in power loading in the moulds, various solutions have been proposed, including constructionally complex ones which are not entirely satisfactory. EP-A-1,008,438 (assigned to the present applicant) relates to a compact, light and structurally simple press which, differently to the prior art, is characterised by a special resistance structure constituted by a plurality of resistance elements each of which comprises an annular element at the centre of which, in diametrically opposing positions, two segments are housed which exhibit a first portion of their edge shaped for coupling with another correspondingly shaped part of the internal edge of the annular element and a second portion of their edge which is located opposite to the first part. Special spacers are provided to keep the second portions at a predetermined distance, so as to generate a space in which at least one power tool can be housed. This power tool exerts the pressing action, by compressing between two elements the material to be formed, but discharging the reaction forces of the pressing operation on the two opposite parts. The main aim of the present invention is to render simpler and more functional both the assembly of the press of EP-A-1,008,438 and the regulation thereof. A further aim of the present invention is to perfect a process for assembling and setting up the press, and to identify the equipment needed for execution of the process. A further advantage of the invention is that it reduces to a minimum the mechanical working of the various parts making up the structure, which in compression force-for-force comparison with the prior art is still characterised by its lightness and its contained mass. A further advantage of the invention is that it is easily transportable because it is composed of parts which are particularly easy to load on existing transport containers. These aims and advantages and more besides are all attained by the present invention, as it is characterised in the appended claims. Further characteristics and advantages of the present invention will better emerge from the detailed description that follows of a preferred but non-exclusive embodiment of the invention, illustrated purely by way of a nonlimiting example in the accompanying figures of the drawings, in which: figure 1 is a schematic front view in vertical elevation; figure 2 is a schematic section made according to line y-y of figure 1; figure 3 is a schematic view of a stage of assembly of the invention; figures 4 and 5 show respectively an intermediate position and the final position of the rotation by which the structure is located in the vertical operative position. With reference to the above-mentioned figures, 1 denotes in its entirety a resistance element which comprises an annular element 2 internally of which two segments 3 are located in diametrically opposite positions. The entire element 1 exhibits a flat configuration in which the first two dimensions, width and height, are much greater than the third dimension, depth, which is constant. In the plane identified by the first two dimensions, width and height, the configuration of the resistance element 1 is symmetrical with respect to at least one axis, y-y. The internal profile of the annular element 2 is substantially constituted by two symmetrical arcs of circumference, reciprocally connected up, to which the first parts of shaped edges 30 of the two opposing segments 3 are coupled. In the example, the first portions of the shaped edges 30 have convex profiles and are geometrically shaped such as to be contactingly couplable to the symmetrically opposite corresponding arc-shaped portions constituting part of the internal edge of the annular element 2. Constructionally, the annular element 2 and the segments 3 are made from a single sheet of steel cut accordingly. The segments 3 are half-moon shaped and exhibit a straight second portion of edge 31 which is opposite to the first portion 30. In particular, the second portions 31 are predisposed to be opposite and facing each other at a predetermined distance, in such a way as to identify a space in which a power tool 5 can be housed, which in the example is a press for powder materials. The tool 5 discharges the equal and opposite reactions of the pressing action on the second portions 31. The coupling of the first portions 30 in the corresponding arc-shaped portions constituting part of the internal edge of the annular element 2 confers freedom of oscillation on the segments 3 with respect to the annular element 2, so that in any situation a relative adjustment is possible of the segments 3 themselves, which brings them into a position at which the respective first portions 30 are both facing one another and parallel. The illustrated embodiment comprises a plurality of identical said resistance elements 1, arranged facing one another and consecutively aligned at predetermined reciprocal distances. The second portions 31, which face each other, of the various resistance elements 1 are kept at a correct reciprocal distance by two spacer devices 14 specially dimensioned and interpositionable between reciprocally facing second portions 31 of the two segments 3 and against opposite tracts of each annular element 2. Each spacer device 14 comprises at least one parallelepiped spacer 4 and for each resistance element 1 at least one wedge 15 predisposed to combine with the spacer 4. Each spacers device 14 exhibits two contact surfaces 16 and 17 which correspond with portions of surface of the second reciprocally-facing portions 31 of the two opposing segments 3. At least one of the surfaces, in the example contact surface 16, exhibits a slightly concave shape (or convex) which is predisposed to couple in a corresponding portion of convex (or concave) surface afforded in the second portion 31, with which it is coupled. The contact surfaces 16 are portions of cylindrical surface. On the contrary, the contact surfaces 17 which are opposite to the contact surfaces 16 are in fact the flat external surfaces of the wedge 15, which are opposite to the surfaces with which the wedges 15 are coupled in direct contact with corresponding surfaces of the spacers 4. The wedges 15 are positionable perpendicular to the longer side of the spacers 4 by means of screw devices 23 activated from the outside of the press and anchored to support elements 18 which are externally fixable to the spacers 4. The support elements 18 are dimensioned such as to be freely insertable in the space between two contiguous annular elements 2, said space being determined by spacer organs 20 interpositioned between two adjacent resistance elements 1. A portion of the first part 30 of the shaped edge of each segment 3 exhibits a profile which is an arc of circumference. The resistance elements 1 which make up the structure singly exhibit a flat configuration in which the first two dimensions, width and height, are much greater than the third dimension, i.e. depth, which is more or less constant. In the plane identified by the first two dimensions, width and height, the configuration of the resistance element 1 is symmetrical with respect to the axis, y-y, which identifies approximately but fairly accurately the vertical direction of the shocks transmitted by the power tool 5 to the two opposite segments 3. The symmetry of each resistance element 1 in the plane identified by the first two dimensions (width and height) with respect to the two axes, is obviously the same as that of the plurality of resistance elements 1 assembled as described herein above. The resistance elements 1 are assembled with a modular arrangement and organisation by virtue of which a variation in the number of the resistance elements 1 assembled means that the maximum press force possible can be varied. The power tool 5 comprises a lower body 6 and an upper body 7 between which objects or the material to be pressed can be inserted, and a pneumatic piston 22 the base of which rests on the overall surface generated by the second portions 31 of the inferiorly-arranged segments 31. The upper body 7 is maintained in contact with the overall surface generated by the second portions 31 of the superiorly-arranged segments 3. The described structure is assembled in the following order. First, the resistance elements 1 are placed on top of another in a horizontal position, with an interpositioning of the spacer organs 20 and support elements 18, as well as the insertion of the spacer devices 14 including the spacers 4 and wedges 15. Next, the spacer devices 14 are tightened to block the segments 3 to the respective annular elements 3. The whole assembly is now turned through 90° in order to locate it in the operative position. The power tool 5 is now mounted, being inserted as a block between the facing second portions 31. At this point the segments 3 can be adjusted if necessary, by acting on the single wedges 15. The power tool 5 can now be started up to bring the whole structure up to a predetermined preload level; then the spacer devices can be definitively regulated by acting on the single wedges 15 until the load is equally distributed, and the power tool 5 can be shut down. Assembly is facilitated by using a special cradle 21 on which the resistance elements 1 are arranged horizontally one on top of another, with the spacer organs 20 and the support elements 18 interpositioned, as well as the spacer devices 14, each of which comprises a spacer 4 and a wedge 15. The cradle 21 is L-shaped, thus allowing a 90° rotation in a vertical plane and enabling the assembled structure to be moved from a horizontal position into a vertical one (the work position). The above-described assembly process is very simple and requires no special or unusual activity. The wedges are adjusted by tightening and loosening screws 23 to the same regulation using a torque key. Use of the same power tool 5 - the one used during normal press operation - to obtain the desired preload is an extremely simple solution which requires no other tools or equipment. The resulting structure has all the components constrained together with forced couplings and no welded joints or bolts. Up to a certain level of applied work load the structure behaves as if it were a single block, but above that certain level the entity of elastic deformation permitted enables the single annular elements to deform independently, with the result that the press structure is in fact free to deform and adapt to any lack of uniformity in reaction to pressing by the actual material being pressed. This is especially useful in ceramic powder pressing, especially tiles. The facing second portions 31 generate the planes to which the power tool 5 is fixed, together with the special die in which the powder material to be formed is compressed. The configuration of the structure is sufficient to guarantee an equal distribution of the load over the annular elements 2 and thus to exploit to the full the resistance capabilities of the whole structure, which behaves as a modular structure able to absorb a total load constituted by the sum of the loads supportable by each of the annular elements 2. The special conformation of the single resistance elements 1, determined by the coupling of the pairs of segments 3 with the corresponding annular elements 2, enables the loads (applied in the direction of axes y-y) to be distributed optimally, a tension being induced on each annular element 2 and distributed such as to achieve a very good overall exploitation of the material. This means that the overall structure is four to five times lighter than traditional presses for a similar load absorption. The simplicity of construction, and especially of assembly, requiring no welding nor screw connections, leads to greater constructional economy and running costs. The modular structure, while leaving the press mouth dimensions unchanged, allows, for example, the maximum pressing force to be increased simply by adding further resistance elements 1. Thus each pressing cycle can be accompanied by a greater productive capacity. The total load that the entire structure can bear is given by the sum of the loads which each resistance element 1 can bear. Further, the smaller dimensions mean that the whole assembly can be transported, located and assembled more easily at destination. The flexibility of the structure allows for innumerable power tool 5 configurations. The tool 5 can be constituted by a rectangular piston which is raised thanks to the thrust received from below by a pressurised-oil-pumped diaphragm, or might instead be a more traditional oval piston inserted in a jacket and having elastic sides and appropriate seals.

Claims: A press structure, in particular for moulding ceramic products, comprising a resistance structure constituted by a plurality of resistance elements (1), arranged side-by-side and aligned consecutively at predetermined reciprocal distances, each of which resistance elements (1) is composed of an annular element (2) internally of which two segments (3) are housed in diametrically opposite positions, which two segments (3) exhibit a first portion (30) of edges thereof which are shaped so as to couple with a correspondingly shaped portion of the annular element (2) and a second portion (31) which is opposite to the first portion (30); the second portions (31) facing one another and being maintained at a distance one from another in order that a chamber is identified there-between, internally of which at least one power tool (5) can be housed; said power tool (5) being destined to exert a pressing action by compressing between two bodies an object or a material to be pressed while discharging equal and opposite reactions of the pressing action between the second portions (31); characterised in that the facing second portions (31) are maintained reciprocally at a distance one from another by two spacer devices (14) which are interpositioned between the second portions (31) of the two segments (3) at two diametrically opposite tracts of each annular element (2); each spacer device (14) comprising at least one parallelepiped spacer (4) and at least one wedge (15) predisposed to combine with the spacer (4). The press structure of claim 1, characterised in that each spacer device (14) exhibits two contact surfaces (16 and 17) which will contact with the two facing second portions (31) of the two opposite segments (3); at least one of the contact surfaces (16 and 17) having a slightly concave shape and being predisposed to couple with a corresponding convex portion of surface afforded in the second portion (31), with which the at least one contact surface (16 or 17) is coupled. The press structure of claim 2, characterised in that at least the contact surfaces (16) which are concave are portions of cylindrical surface. The press structure of claim 2 or 3, characterised in that the contact surfaces (17) which are situated opposite to the concave contact surfaces (16) are external flat surfaces of the wedges (15), which external flat surfaces are opposite to working surfaces with which the wedges (15) are coupled by direct contact with surfaces of the spacer (4). The press structure of claim 4, characterised in that the wedges (15) can be positioned perpendicularly to a larger side of the spacers (4) by means of devices anchored on support elements (18) externally fixable to the spacers (4). The press structure of claim 5, characterised in that the support elements (18) which are externally fixable to the spacers (4) are dimensioned so as to be freely insertable in a space existing between two contiguous annular elements (2), said space being afforded due to spacer organs (20) interpositioned between two adjacent resistance elements (1). The press structure of claim 5 or 6, characterised in that the devices by means of which the wedges can be positioned perpendicularly to the larger side of the spacers (4) are screw-type devices which can be tightened or loosened from outside the structure. The press structure of claim 7, characterised in that the resistance elements (1) can be assembled with a modular arrangement and configuration, so that a variation in a number of the resistance elements (1) assembled enables a maximum pressing force of the structure to be proportionally varied. The press structure of claim 8, characterised in that at least a portion of the first portion (30) of a shaped edge of each segment (3) is an arc of circumference. The press structure of claim 9, characterised in that the resistance elements (1) singly exhibit a flat configuration in which two dimension, width and height, are considerably bigger than a third dimension, depth, which depth is constant; a plane identified by the dimensions of height and width being symmetrical with respect to at least one axis (y-y) which identifies a direction of stress forces transmitted by the power tool (5) to the two opposite segments (3). The press structure of claim 10, characterised in that the axis (y-y) which identifies the direction of the stress forces transmitted by the power tool (5) to the two segments (3) is vertical. The press structure of claim 11, characterised in that the power tool (5) comprises a lower body (6) and an upper body (7) between which the objects or the material to be pressed can be inserted; a pneumatic piston (22) being included having a base which rests on a surface created by the second portions (31) of the inferiorly-arranged segments (3); the upper body (7) being maintained in contact with a surface created by the second portions (31) of the superiorly-arranged segments (3). A process for assembly of the press structure of any one of the preceding claims, characterised in that the process is carried out in the following order: the resistance elements (1) are placed on top of another in a horizontal position, with an interpositioning of the spacer organs (20) and support elements (18), as well as insertion of the spacer devices (14) including the spacers (4) and wedges (15); the spacer devices (14) are tightened to block the segments (3) to the respective annular elements (2); the whole assembly is turned through 90° in order for it to be located in an operative position; the power tool (5) is mounted, being inserted as a block between facing second portions (31); the segments (3) are adjusted if necessary, by acting on the single wedges (15); the power tool (5) is started up to bring the whole structure up to a predetermined preload level; the spacer devices are definitively regulated by acting on the single wedges (15) until they load is equally distributed; the power tool (5) is shut down. The process of claim 13, characterised in that the resistance elements (1) are arranged one above another in a horizontal position on an L-shaped cradle (21) which can be rotated by 90° in a vertical plane.

Inventors: STEFANI FRANCO, STEFANI, FRANCO
Applicants: RONFLETTE S A, RONFLETTE S.A.
Application year: 2000
Main classification: B30B15
IPC codes: B28B3, B30B15