Pressing device

Abstract: A press that includes a frame body with vertically extending walls (2) interconnected by connecting means (4, 32, 34) and provided with respective openings (6) that together define a pressing compartment of adequate size to hold upper pressing means (14) associated with upper block means (18) and lower pressing means (16) associated with lower block means (24); the vertical actuating means (40; 40a, 42) has a pressing surface that extends in such a way as to occupy at least a substantial portion of the surface to be pressed; the lower pressing means (16) is coupled to actuating means (72, 76, 78) capable of moving it to an auxiliary position (66) in which it can be discharged of pressed product and loaded with further loose material to be pressed.

Description: The invention relates to a pressing system, in particular for shaping powdered ceramic materials of flat shape and, in particular but not solely, of large format. Known presses consist of a welded or assembled structure to which there is coupled a vertically mobile beam bearing a top mould portion, said mould having a respective lower portion coupled to the bench body of the press. Presses of assembled structure consist of a pair of walls connected by a pair of tables assembled in such a way as to define a pressing compartment in which a mobile mould punch is capable of closing onto a die-box containing the powders to be shaped. Known ceramic presses can generate a pressing force of only up to 4,000 or 5,000 tonnes and are therefore unable to press ceramic slabs of surface area greater than 1 sqm. Therefore, the problem arises of how to improve ceramic presses in order to make possible, in particular, to improve their performances for pressing ceramic slabs of surface area greater than 1 sqm. FR-A-345 819 describes a method for producing a press including a frame body with vertically extended wells interconnected by connecting means. According to the invention, the posed problem is solved by a press having the features of claim 1. The invention allows for creation of a press with a modular structure, in other words a press with a longitudinal dimension of the compartment that receives the pressing means having a length that can be freely predetermined according to the surface area of the material to be pressed. The upper block and the lower block serve to distribute the load uniformly on the walls during pressing. It Is therefore preferable for each wall to be relatively close to the previous and/or subsequent wall. As a guideline, the walls can be a distance apart that is roughly equal to their thickness. In an other aspect of the Invention, there is provided a press comprising a frame body to which there is coupled upper pressing means which interacts operatively with lower pressing means In a pressing position in order to press a loose material between them in such a way as to form a pressed product, wherein said lower pressing means is coupled to actuating means capable of moving the lower pressing means from said pressing position to an auxiliary position in which the lower pressing means can be discharged of pressed product and loaded with further loose material to be pressed. This aspect of the invention permits optimal loading of ceramic powders in the die-box of a mould for ceramic tiles or for large-format ceramic slabs. Furthermore, it is possible to increase productivity by using two die-boxes as the lower pressing means and introducing them alternately below the same punch in the same press. In fact, while one of the die-boxes is being loaded with the powders to be pressed, the other can be positioned under the punch during the pressing stage. The invention can be better understood and carried into effect by referring to the attached drawings, which illustrate some versions of it and are intended purely as non-limiting examples, in which: Figure 1 is a front view of a press; Figure 2 is a top view of the press shown in Figure 1; Figure 3 is a fragmentary view taken along plane III-III in Figure 1; Figure 4 is a sectional view taken along plane IV-IV in Figure 3 showing the hydraulic jack actuating means; Figure 5 is a sectional view taken along plane V-V in Figure 4; Figure 6 is a sectional view like the one shown in Figure 4, but in a variant of the hydraulic jack actuating means; Figure 7 is a sectional view taken along plane VII-VII in Figure 6; Figure 8 is a sectional view like the one shown in Figure 3, showing schematically actuating means for moving a die-box capable of containing ceramic powder in and out of the press; Figure 9 is a schematic sectional view IX-IX shown in Figure 8; Figure 10 is a sectional view like the one shown in Figure 8, but in a version with two mobile die-boxes on opposite sides of the press; Figure 11 is a schematic top view of the actuating means shown in Figure 10; Figure 12 is a schematic view from the right of Figure 11, in which the extracting means moves a pressed ceramic slab from the die-box and deposits it on a movement line; Figure 13 is a view like the one in Figure 12, but showing loading of the die-box with powders to be pressed. As shown in Figure 1, a press 1 for ceramic slabs or large-format ceramic tiles has a frame body including walls 2, which are interconnected by way of two pairs of tie-rods 4 situated in respective holes in walls 2 below and above an opening 6 in each wall 2. Each wall 2 rests on a base frame 8 relative to which it is positioned by way of a conventional alignment device 10. The set of holes 6 in walls 2 forms a compartment that accommodates the pressing means 12 comprising upper pressing means 14 and lower pressing means 16. As shown in Figure 2, the walls 2 all have the same nominal thickness S and are positioned at a distance D apart, substantially equal to the nominal thickness S. This way the set of walls 2 is loaded uniformly when it has to withstand pressing loads. In a specific case, the following relationship is found: D = S = 200 mm ∼ The upper pressing means 14 includes an upper block 18 which is fixed to walls 2 on the top edge of openings 6, and is interconnected with a punch body 20 by way of vertical actuating means 22, including jacks 60 with rods 62 engaged in punch body 20 and arranged at the corners of upper block 18. Between upper block 18 and punch body 20 there are interposed guide columns 30 which slide in holes 32 (Figure 3) on upper block 18 and are capable of ensuring that the punch body 20 moves downwards and upwards in a vertical plane. The lower pressing means 16 includes a lower blocks 24 which is fixed to walls 2 on the lower edge of openings 6 and at the top has a pair of horizontal slide guides 26, coupled to respective lifting means 27. A die-box body 28 is slidingly engaged on said sliding guides and is capable of receiving the punch body 20, in particular a lower active surface 44 thereof, in an upper cavity 29 (Figure 3) on said die-box body 28. The lifting means 27 is able to move the die-box body 28 upwards when, at the end of a pressing stage, said die-box body must be moved to a remote position relative to punch 20 in order to allow pressed product to be removed and further powders for pressing to be introduced into cavity 29; this aspect will be described in greater detail below. The set of walls 2 of the frame body of press 1 form a "sandwich" type structure in which the walls 2 are maintained in pre-established positions relative to each other by spacers 32 interposed between each wall 2 and the wall 2 immediately preceding or following it. Naturally, a "sandwich" type press structure as defined above can also be fitted with conventional moulds, in particular with moulds that do not have parts that move transversally relative to the direction of movement of the punch. As shown schematically in Figure 3, spacers 32 are arranged in an external coaxial fashion on tie-rods 4, which securely tighten walls 2 by way of ring nuts 34 which engage with the ends of each tie-rod 4. The upper block 18 is positioned on the top part of openings 6 by way of upper horizontal pins 35 and is fixed to walls 2 by way of upper fixing screws 36 with interposed anti-friction laminas 38. A piston body 40 fixed to the bottom portion of block 18 by way of screws 39 penetrates, and forms a seal with, a recess 42 in punch body 20. This way the punch body 20 serves as the lining of a pressing hydraulic jack, the piston of which is the piston body 40 fixed to walls 2 in the manner described above. The die-box body 28 includes an external frame body 46, which can be raised and lowered by way of further vertical actuating means 50, consisting of hydraulic jacks, solidly fixed to a base body 48 which extends upwards and is surrounded by an external frame body 46 which can slide vertically on the upper portion of the base body in such a way that, when the frame body 46 is completely raised, cavity 29 is formed between the die body and an active upper surface 52 of the base body, whereas when the frame body 46 is fully lowered, cavity 29 disappears and a product that has been formed inside it can be removed. The lower block 24 is positioned on and fixed to walls 2 by way of screws 54 and horizontal pins 56 in a similar manner to the upper block 18. The die-box body 28, in particular the lower part of the base body 48, rests on the lower block 24 and can slide relative to it on the slideways 26; the die-box body 28 can be centred in a pressing position below punch 20 by way of centring means 58 consisting of lower conical projections of the base body 48 which can engage with corresponding seats in the lower block 24. As shown in Figure 4, the piston body 40 has a substantially rectangular shape with radiused comers, in such a way as to extend substantially over the entire surface of product P to be pressed, as defined by the cavity 29 when the die-box body 28 is in the pressing position. As shown in Figure 5, a sheet 64 of anti-friction material is interposed between the piston body 40 and the upper block 18. Furthermore, alignment bushings 31 are interposed between the guide columns 30 and the holes 32 on the upper block 18 in which said guide columns slide. Figure 6 shows a version of the upper pressing means which is similar to the version described in Figures 4 and 5 but in which, instead of a single piston body 40, there is a pair of piston bodies 40a arranged in such a way as to occupy a considerable part of the surface in plan view of product P to be pressed. As shown in Figure 7, the piston bodies 40a are received in respective recesses 42a in punch body 20; during pressing, oil is sent into each of the recesses 42a at the same pressure and flow rate, in order to ensure that the active face 44 of punch body 20 exerts a uniform pressure on the powders to be pressed. Naturally, the "sandwich" structure of the press can also be equipped with a single conventional piston of circular cross-section. As shown in Figure 8, on one side of press 1 in a longitudinal direction X passing through the compartment formed by the set of openings 6 in walls 2, there is situated an auxiliary station 66 to which the die-box body 28 is moved to a waiting position after pressing, as shown by the dashed line in the righthand section of Figure 8. The lifting means 27 raises the die-box body 28 to free the centring means 58 until the slideways 26 are aligned with sliding tracks 68 machined on a support structure 70 on waiting station 66. On the die-box body 28, there is closed-loop chain transfer means 72 wound on wheels free to rotate 76, which define a path with a neutral branch passing underneath the base of the press 1. On either side of the press 1, the wheels free to rotate 76 are coupled to geared motors 78 in such a way that the die-box body 28 can be moved along direction X from the pressing position to the waiting position and vice versa, making wheels 80, mounted on the bottom of the die-box body 28, run along the slideways 26 and the sliding tracks 68. Figure 9 shows the dashed outline of auxiliary means 81 which acts on the die-box body 28 as explained below, when said die-box body is in the waiting position. As shown in Figure 10, to increase productivity it is possible to have two auxiliary stations 66 and 66a located on opposite sides relative to press 1, consisting of analogous parts to those making up auxiliary station 66 and therefore designated with the same reference numbers. However, unlike the version referred to in Figures 8 and 9, instead of a single die-box body 28, there are two die-box bodies 28 interconnected by the chain connecting means 72. They are positioned in such a way that when one die-box body 28 is in the pressing position, the other is in the waiting position in auxiliary station 66, whereas when this second die-box body moves to the pressing position inside the press, the first die-box body moves to the waiting position in auxiliary station 66a. This way, while one die-box body undergoes the action of the punch body 20, the other is disengaged from the press 1 and can be discharged of product P and loaded with further powdered material to be pressed. Figure 11 shows the dashed outline of auxiliary means 81 which acts on die-box body 28 as explained below, when it is in the waiting position relative to auxiliary station 66a. As shown in Figure 12, when the die-box body 28 reaches the auxiliary station 66 or 66a, the frame 46 is lowered by the vertical actuating means 50 so as to free the pressed product P on the surface of the base body 48. The auxiliary means 81 includes transversal guide means 82, positioned transversally relative to direction X and on which a suction-cup pick-up means 84 is slidingly engaged. Said suction-cup pick-up means moves vertically on a pair of columns 86 by way of transfer means 88 and is capable of picking up pressed product P from die-box body 28, then raising said pressed product P from said die-box body and transferring it to a conveyor line 90 equipped with a motor-driven roller conveyor. After the die-box body 28 has been freed from pressed product P, the frame 46 is once again raised in such a way as to form cavity 29, as shown in Figure 13, and hopper means 92 containing powders to be pressed is moved in such a way that a lower discharge outlet 94 controlled by shutter means 96 can introduce the powders to be pressed into cavity 29. Once cavity 29 has been filled, the hopper means 92 is moved to a rest position where it receives further powder from a feeder belt 98.

Claims: A press, including a frame body with vertically extending walls (2) Interconnected by connecting means (4, 32, 34) and provided with openings (6) that together define a pressing compartment of adequate size to contain upper pressing means (14) and lower pressing means (16), an upper portion of said compartment being occupied by upper block means (18) which is stably coupled to the upper parts of said openings (6) and to which said upper pressing means (14) is fixed, a lower portion of said compartment being occupied by lower block means (24), which is stably coupled to the lower parts of said openings (6) and to which said lower pressing means (16) is fixed, characterised in that said walls (2) are close to the previous and the following one and are separated from the previous and following walls by a distance (D) that substantially corresponds to the nominal thickness (S) of each wall (2). Press according to claim 1, wherein piston means (40; 40a) of said upper pressing means (14) is fixed to said upper block (18). Press according to claim 2, wherein said piston means (40) forms a single bodies whose cross-section is of a size corresponding substantially to the surface area to be pressed. Press according to one of claims 1 to 3, wherein said piston means (40a) is divided into individual piston bodies whose overall cross-section is of a size corresponding substantially to the surface area to be pressed. Press according to one of claims 2 to 4, wherein said upper pressing means (14) includes a punch body (20) provided with recess means (42; 42a) to receive said piston means (40; 40a) and coupled in such a way as to move in a guided manner relative to said upper block means (18). Press according to one of the previous claims, wherein said lower pressing means (16) is coupled to said lower block means (24) in such a way as to be disengageable in a vertical direction. Press according claim 6, wherein said lower pressing means (16) is provided with centring means (58) on said lower block means (24). Press according to one of claims 6 or 7, wherein said lower pressing means (16) includes a base body (48) peripherally engaged by frame means (46) which can be moved in a vertical direction relative to said base body (48) in such a way as to define a pressing cavity (29). Press according to one of claims 6 to 8, wherein said lower pressing means (16) is coupled to horizontal actuating means (72, 76, 78) capable of moving the lower pressing means (16) from a pressing position in which said lower pressing means (16) can interact with said upper pressing means (14) to an auxiliary position (66) in which the lower pressing means (16) can be discharged of pressed product and loaded with loose material to be pressed. Press according to claim 9, wherein said lower pressing means (16) includes a die-box body (28) and said auxiliary position is on one side of the press (1). Press according to claim 9, wherein said lower pressing means (16) includes two separate die-box means (28), each of which has an auxiliary position on its respective side of the press (1). Press according to one of claims 9 to 11, wherein said actuating means (72, 76, 78) is a flexible actuating means.

Inventors: CHIODI MAURIZIO, MONTECCHI SANTE, CHIODI, MAURIZIO, MONTECCHI, SANTE
Applicants: SYSTEM SPA, SYSTEM S.P.A.
Application year: 1998
Main classification: B28B5
IPC codes: B28B3, B30B15, B28B5