IT202000016021A1 - PRESSING APPARATUS - Google Patents

Description

Description of the invention entitled:

"PRESSING APPARATUS"

FIELD OF APPLICATION

The present invention relates to a pressing apparatus, in particular to an apparatus capable of developing high pressure forces capable of plastically deforming a material being processed until it is reduced to the desired shape. The aforementioned device? usable for example for metalworking, for example for forging, forging, moulding, punching, shearing, but also for molding plastic materials, for forming ceramic products, or more.

STATE OF THE ART

As ? known, pressing apparatus or machines, simply called presses, are used in various industrial fields.

A general configuration of a known press allows a component called ?mold? to be inserted into a suitable housing. in turn made up of two further parts called ?mold? and ?countermold?. The press has the task of reciprocally moving the ?mold? and ?countermould? closing or opening.

The operation of closing the mold and the countermould against each other has the aim of producing or processing objects of different kinds, for example metal, plastic, ceramic or other objects.

It is possible to identify some main components of the press:

? the crosspiece or element called the crosspiece, which rests on the counter-mold and in general ? the mobile part of the press;

? the base where in general ? placed the mold, it ? the fixed part of the press;

? the element that generates the closing force or pushes the crosspiece against the base in order to close the mold with the correct pressure.

There are mainly two performances that a press must achieve: ? exert a pressure uniformly distributed over the entire surface of the mold so that? this is correctly tightened and is not damaged;

? open and close the mould, then place the mold on the countermould or vice versa ensuring correct parallelism between said components.

For simplicity? we can divide the presses, or pressing apparatuses, into two types as indicated in fig. 1 and fig. 2.

The pressing apparatus 20 of fig. 1 comprises a crosspiece 21, a base 22, means 23 for moving the crosspiece 21, for example hydraulic pistons, a countermould 24 on which the crosspiece 21 rests and a mold 25 which in turn rests on the base 22.

These means 23 are positioned on the sides of the crosspiece 21 and pull said crosspiece 21 against the base 22 in order to mutually compress the mold 25 and the countermould 24.

The pressing apparatus 26 of fig. 2 comprises means 27 for moving the crosspiece 21 which act at the center of the crosspiece 21. Substantially these means 27 are associated with a structure 28 for containing the pressing apparatus 26.

These pressing apparatuses 20 and 26 mainly have two types of defects:

? defect? elastic or elastic structural failure;

? defect? geometric or assembly and manufacturing tolerances of the various components.

In the pressing apparatus 20 of fig. 1, the forces determined by the actuation of the means 23 act respectively on the crosspiece 21 and on the base 22 in order to push the counter-mold 24 against the mold 25.

Both the crosspiece 21 and the base 22 are normally deformed by pushing more on the corners of the mold 25 and of the countermold 24 and the pressure ? greater at the ends? of the mold 25 and of the countermold 24, while it decreases in the centre.

Therefore, this pressing apparatus 20 presents an evident problem of inhomogeneity? of closing pressure between the mold 25 and the countermold 24. Even if both the cross member 21 and the base 22 were stiffened, this problem would continue to arise and furthermore the weights of said components would increase, as would the production costs.

Also the pressing apparatus 26 presents bending problems of the cross member 21 and of the base 22 when the means 27 operate the cross member 21 which pushes the counter mold 24 against the mold 25.

The bending of the mold 25 and the counter-mould 24 causes strong sliding forces between said mold 25 and the counter-mould 24 which, in addition to misaligning the figures, degrading the quality? you say? which is produced, ruin said components.

The defects? geometry of the known pressing apparatuses are substantially deriving from how the pressing apparatuses are constructed and from inevitable manufacturing errors; a perfect manufacture? in fact impossible to achieve.

With regard to the configuration of the pressing apparatus 20 of fig.

1, but the argument would be analogous also for the pressing apparatus 26 of fig. 2 or other configuration, in fig. 3a the cross 21 to which ? joint the counter mold 24 ? inclined by an angle a with respect to the base 22, consequently also called countermold 24 ? inclined with respect to the mold 25 that ? supportive of the base 22.

This inclination of said angle to pu? be caused by construction errors and assembly errors.

fig. 3b ? a view rotated 90? of the pressing apparatus 20 of fig.

3 a with respect to a vertical axis, in which a second inclination of an angle ? which, like the first, causes a lack of parallelism between the mold 25 and the countermold 24 at their interface.

Said undesired inclinations are particularly harmful in the case of the so-called ?Try Mold? presses.

The presses known as ?Test Mould? are they a subgroup of presses designed to mutually put the mold and the countermold in contact so that an operator can evaluate the goodness? of the interface and correct any defects? manufacturing of said mold and countermould.

It is therefore clear that a fundamental prerogative of the presses called ?Mould Test? both to be themselves a reference of parallelism between the crossbar and the base why? said reference of parallelism ? used to understand if the mold and countermold are parallel to each other or if they need to be modified to be so.

A further prerogative of the presses called ?Prova Mould? ? that of presenting the pressing unit, both the mold and/or the countermould to the operator, or rather they have the possibility? to rotate with respect to a substantially horizontal axis so as to be able to examine the surface of the counter-mold and of the mold which will come into contact with each other. These presses generally have a pair of uprights to which ? the crossbar carrying the counter-mold is connected. This cross? connected to these uprights by means of sliding supports and vertically to hinges which allow it to rotate with respect to a substantially horizontal axis.

These hinges allow an inspection of the surfaces of the mold and of the counter, by rotating the counter after it? been suitably spaced from the mould. However, these hinges cannot remedy the defects? geometrical characteristics of the press, as they are not suitable for the transmission of the force generated by the means of movement of the crosspiece.

A known attempt to mitigate the defects? springs of the known pressing apparatuses, for example the pressing apparatuses 20 and 26, ? that of giving a convex shape to the crosspiece in the central contact area with the counter-mold 24.

However, this solution proves to be ineffective and increases the complexity? construction of the crosspiece and of the pressing apparatus. Make a crosspiece having a precise convexity? ? in fact a very complicated operation and often does not provide the desired results.

Furthermore, the crossbar has a convexity? ? usable substantially only for a certain nominal pressure, while if you want to vary the pressure that said crosspiece must exercise, do problems of inhomogeneity still arise? of the applied pressure and unwanted bending of said crossbar and of the base of the pressing apparatus.

Is there therefore a need? to perfect a pressing apparatus which can overcome at least one of the drawbacks of the prior art.

In particular, an object of the present invention ? that of realizing a pressing apparatus in which the typical drawbacks of known pressing apparatuses, relating in particular to defects, are eliminated or at least limited. elastic, i.e. elastic structural yielding, mainly due to a non-uniform and homogeneous application of pressure between the pressure elements that make up the pressing apparatus.

Another object of the present invention ? that of realizing a pressing apparatus in which further defects typical of the known pressing apparatuses are eliminated or at least limited, relating in particular to the defects? geometric, or in particular assembly defects and manufacturing tolerances of the various components.

A purpose of the present invention ? therefore ultimately the creation of a pressing apparatus which can operate in a precise, reliable manner and with a uniform and homogeneous pressure exerted by the pressure elements which compose it, even by varying the pressure exerted by the pressing apparatus.

To obviate the drawbacks of the prior art and to obtain these and further objects and advantages, the Applicant has studied, tested and implemented the present invention.

DISCOVERY DISPLAY

The present found ? expressed and characterized in the independent claim. The dependent claims disclose other characteristics of the present invention or variants of the idea of the main solution.

In accordance with the above purposes, a pressing apparatus according to the present invention comprises at least one pair of pressing elements aligned along a pressing direction, in which at least one first pressing element ? associated with movement means along this pressing direction and ? pushed towards a second pressure element by at least one movable element and according to a thrust surface defined on the movable element.

According to one aspect of the invention, between this movable element and this first pressure element? positioned at least one calibrated shim on at least a portion of this thrust surface.

Advantageously, the present pressing apparatus, through the use of at least one calibrated thickness, allows to eliminate or at least limit the drawbacks typical of known pressing apparatuses, relating in particular to defects in the pressing apparatus. elastic, i.e. of elastic structural yielding, allowing a uniform and homogeneous application of the pressure between the pressure elements that make up the pressing apparatus.

This pressing apparatus can? moreover, operate in a precise, reliable way and the use of at least one calibrated thickness has various advantages, among which the simplicity? constructive, l?economicity?, the simple availability? and the fact that can? be easily replaced with one of greater or lesser thickness when the need arises? to increase or decrease the closing pressure of the pressing apparatus.

Furthermore, the use of at least one calibrated thickness also has considerable advantages in "Mould Test" presses, which constitute a geometric reference for the molds which are tested in them.

This mobile element can be a crossbar resting on said first pressure element and connected to said movement means.

This calibrated thickness pu? be connected in a removable manner and by means of suitable fastening means to this mobile element.

According to further aspects of the invention, this thrust surface can be covered at least partially by a plurality? of plates and such at least one calibrated thickness can? be positioned between at least one plate of this plurality? of plates and such thrust surface.

In embodiments, such a movable element can understand two ends? arranged to the side of this first pressure element and this second pressure element and associated with these means for moving the mobile element; this calibrated thickness can? be positioned between this movable element and this first pressure element in a central region of this thrust surface.

Said movement means could also be associated with a central area of the movable element located on a surface opposite to the thrust surface; in this case, this mobile element can? be provided with at least a pair of calibrated shims located in lateral areas of this thrust surface.

In embodiments, such a movable element can be connected to the ends? respective supports positioned along translation guides along this pressing direction and comprising, at said ends, pins inserted in said supports and able to allow rotation of said movable element with respect to said supports; this mobile element can? be bound to each of these supports by one or more? adjustment devices configured to allow stable locking of the movable element in any position with respect to said supports. This adjustment device can comprising a movable part configured to be inserted in a seat of the movable element and to receive at least one pin housed in this movable part and in a seat formed in this support; such a moving part ? configured to translate at least along said pressing direction so as to substantially vary the geometric position of the seat where this pin is inserted. This adjustment device can comprising at least one wedge cooperating with said movable part to translate it in one direction or the other at least along this pressing direction; this wedge can? be associated with movement means which allow it to be translated at least along a direction substantially perpendicular to this pressing direction.

Furthermore, this wedge can comprising at least one inclined base surface resting on an inclined plane formed in this seat and a flat upper surface on which the movable part of the adjustment device rests.

ILLUSTRATION OF THE DESIGNS

These and other aspects, characteristics and advantages of the present invention will become clear from the following description of embodiments, provided by way of non-limiting example, with reference to the accompanying drawings in which:

- fig. 1 ? a schematic view of a first known pressing apparatus; - fig. 2 ? a schematic view of a second known pressing apparatus; - figs. 3a and 3b are two schematic views illustrating defects geometry of the pressing apparatus of fig. 1 ;

- fig. 4 ? a schematic view of a pressing apparatus according to an embodiment of the present invention;

- figs. 5a and 5b are two axonometric views of a mobile element of the pressing apparatus of fig. 4;

- figs. 6a and 6b are two schematic views of the pressing apparatus of fig. 4 in operating conditions;

- fig. 7 is a schematic view of a pressing apparatus according to a further embodiment of the present invention;

- fig. 8 ? an axonometric view of a mobile element of the pressing apparatus of fig. 7;

- fig. 9 ? an axonometric view of the mobile element of the pressing apparatus in fig. 4 and/or of fig. 7;

- fig. 10 ? an axonometric view of the mobile element in fig. 9; - fig. 11 ? an enlarged view of a part of the movable element of fig. 9 and fig. 10;

- fig. 12 ? an axonometric view of a movable element equipped with adjustment devices;

- fig. 13 ? an enlarged view of a part of the movable element of fig. 12;

- figs. 14a and 14b are two views which schematically illustrate the operation of the adjustment devices.

For ease of understanding, identical reference numerals have been used wherever possible to identify identical commonalities in the figures. It should be understood that elements and features of one embodiment may be conveniently combined or incorporated into other embodiments without further specification.

DESCRIPTION OF EMBODIMENTS

Will it be done? now reference in detail to the possible embodiments of the invention, of which one or more? examples are illustrated in the attached figures by way of non-limiting example. Even the phraseology and terminology used here? for non-limiting example purposes.

With reference to the attached drawings, see for example figures 4, 5a and 5b, a pressing apparatus 30a comprises at least one pair of pressing elements 29 and 31 aligned along a pressing direction A, in which at least one first pressing element 29? associated with means 32 for movement along said pressing direction A and ? movable towards a second pressure element 31 by means of at least one mobile element 33 and according to a thrust surface 34 defined on the mobile element 33. Between this mobile element 33 and this first pressure element 29? positioned at least one calibrated shim 35 on at least a portion of said thrust surface 34.

How can you? observe in fig. 7 and fig. 8, the pressing apparatus 30b also comprises at least one calibrated thickness 35 on at least a portion of this thrust surface 34.

This first pressing element 29 can? be, for example, a countermould, while this second pressure element 3 1 can? be a mold resting on the base 36 of the pressing apparatus 30a.

The moving means 32 of the mobile element 33 can be hydraulic pistons, pneumatic pistons or even electric systems based on kinematic chains and common electric motors, or other.

This mobile element 33 can be a crossbar resting on said first pressure element 29 and connected to said movement means 32.

The calibrated thickness 35 pu? be removably connected to the thrust surface 34 by means of suitable fastening means 37, for example screws, bolts or the like.

This calibrated thickness 35 pu? be a sheet of metal, easily available on the market, pu? be cut to the desired size and there is a wide range of thicknesses with differences also in the? order of hundredths of a millimetre.

The thrust surface 34, how can you? observe in figures 5a and 5b, pu? be covered by a plurality? of plates 38, 39, 40. The calibrated thickness 35 will come? positioned between at least one plate, for example the plate 39 of fig. 5a, of one of said plates 38, 39 and 40. These plates 38, 39, 40 can for example be screwed to the thrust surface 34. The plates 38, 39, 40 can partially or totally cover the thrust surface 34. In case of the apparatus 30b of fig. 7 and fig. 8, for example two calibrated shims 35 are provided positioned between the thrust surface 34 and the plates 38 and 40.

In the pressing apparatus 30a, the movable element 33 comprises two ends? 41 and 42 arranged to the side of said first pressing element 29 and said second pressing element 31 and associated with said means 32 for moving the mobile element. In this case, the calibrated shim 35 is positioned between said mobile element 33 and said first pressure element 29 in a central area 43 of said thrust surface 34.

When the mobile element 33 flexes why? pulled by the movement means 32, see fig. 6a, first a push is exerted where ? once the calibrated shim 35 has been placed, therefore in a central area, subsequently, the bending also brings the mobile element 33 into contact at the sides of the pressure element 29. In this regard, see the graph in which the pressure trend P ? constant along the entire extension of the thrust surface 34.

The calibrated thickness 35 has the advantage that it can? be easily replaced with one of greater thickness when you need? to increase the closing pressure of the pressing apparatus.

In fig. 6b, for example, if it is foreseen to exert a pressure P1 greater than the pressure P exerted in fig. 6a, ? Is it possible to replace the calibrated thickness 35 with a calibrated thickness 35? of greater thickness, which in any case guarantees a uniform distribution of pressure on the pressure element 29, as indicated by the diagram.

In combination or as an alternative to what has just been described, would it also be possible to envisage the use of more? 35 calibrated thicknesses placed one on top of the other in order to obtain a desired overall thickness.

The use of the calibrated thickness 35 ? therefore advantageous compared to the use of a crossbar equipped with convexity? why? ? easily replaceable and easily installable according to the needs? of the pressing apparatus 30a or 30b, which are in particular those of being able to reciprocally close the pressure elements 29 and 31, for example the mold and the counter-mould, at different pressures and also correctly press pressure elements of different sizes.

The use of at least one calibrated thickness 35 assumes considerable importance when referring to the ?Mould Test? presses, as these presses are more? of any other type of presses are suitable for closing molds or molds against the counter of the pi? different geometry and always different pressures, contrary to a production press which often acts on a single type of mould.

Therefore, in the case of mold test presses, the solution which provides for the use of at least one calibrated thickness 35 allows to limit the defects. geometric shapes and has the same advantages that can be found for the pressing apparatus shown, i.e. ease? replacement and simplicity? constructive or market finding in order to reduce costs by increasing the performance of this type of pressing equipment. For the pressing apparatus 30b illustrated in fig. 7 similar considerations apply regarding the advantages deriving from use of calibrated shims 35.

In particular, in the pressing apparatus 30b, the means 44 for moving the mobile element 33 are associated with a central area of the mobile element 33 located on a surface 45 opposite to the thrust surface 34. In particular, this surface 45 ? the outer upper surface of the mobile element 33. In this case, two calibrated shims 35 located in lateral areas 46 and 47 of the thrust surface 34 can be provided.

Also in this case, the calibrated shims 35 can be connected to the thrust surface 34 by means of fastening elements, such as screws, bolts or the like.

Said calibrated shims 35 can for example be positioned between the plates 38 and 40 and said thrust surface 34. The plates 38 and 40 will then be fixed to the thrust surface 34 by means of screws, bolts or the like. Therefore, in the case of movement means 44 positioned centrally with respect to the mobile element 33, ? it is preferable to position calibrated shims 35 on the sides of the thrust surface 34, so as to obtain a uniform and homogeneous distribution of pressure over the entire thrust surface 34, to compensate for the bending which could be generated on the central part of the mobile element 33.

The base 36 of the pressing apparatus 30a, 30b could also be provided with one or more? suitably positioned calibrated thicknesses. The movable element 33 could be equipped with pins 48 which allow it to be used also in the so-called ?Mould test? presses, see for example fig. 8.

These pins 48, of which in fig. 8 ne ? visible only one, allow the movable element 33 to be positioned on supports 49 and 50 sliding along guides 51 and 52, see also fig. 9.

The pins 48 of the mobile element 33 will engage in a rotatable manner in suitable seats obtained in said supports 49 and 50 and the mobile element will be able to rotate around an axis B. This axis B ? a substantially horizontal axis and allows the rotation of the mobile element 33 so as to make the thrust surface 34 or the surface of the pressure element 29 clearly visible which will go? to engage on the surface of the pressure element 31, if the pressure element 29 is solidified to this mobile element 33.

Substantially, the position of the mobile element 33 of fig. 9 ? identifiable as an inspection position, while that of fig. 10 ? identifiable as a pressing position.

In the pressing position, however resistant the pins 48 are in general they are not? it is advisable that only they are solicited by the pressing force.

Also always during pressing ? important that the mobile element 33 does not move by rotating around the pins 48 along the direction B.

To lock the position of the mobile element 33 with respect to a certain inclination, for example the inclination it presents in the pressing position of fig. 10 but also the inspection position of fig. 9, ? It is possible to use the solution of Fig. 11.

In the supports 49 and 50, see for example the support 50 illustrated in fig.

11, can? a first seat 53 aligned with a second seat 54 formed in the mobile element 33 can be obtained. a pin 55 can be inserted which locks the mobile element 33 with respect to said supports 49 and 50.

Substantially, this pin 55 makes the mobile element 33 integral with the supports 49 and 50 and also takes care of the transmission of the force to the mobile element 33.

Once the pin 55 engages in the mobile element 33, blocking the rotation, according to how the whole system? constructed and compatibly with the inevitable constructive errors and tolerances, geometric errors may occur as in figures 3a and 3b.

According to the present invention , the use of one or more adjustment devices 56, see fig. 12 and fig. 13, configured to allow stable locking of the mobile element 33 with respect to the supports 49 and 50. See for example the adjustment devices 56 of fig. 12 associated with the mobile element 33, in this case two on each side.

These adjustment devices 56 help to correct the geometrical errors when the pressing apparatus 30a, 30b is put into service.

Substantially, each of said adjustment devices 56 allows to modify the geometric position of the seat 54 where the pin 55 is inserted.

This adjustment device 56 is based on the concept of a wedge or cam. This adjustment device 56, see fig. 13, comprises a movable part 57 adapted to slide on the interior of the seat 54 obtained in the mobile element 33. This mobile part 57 can? scroll, upwards or downwards in said seat 54, by how much? sufficient to compensate for manufacturing and/or assembly errors, therefore we are talking about a few millimetres.

In this mobile part 57 ? obtained at least a through hole 59 where will it come? pin 55 inserted.

The adjustment device 56 also comprises a wedge 60 adapted to slide on an inclined plane 61 obtained at the base of the seat 54. In particular, see also fig. 14b, the wedge 60 comprises a base surface 62 with an inclination corresponding to that of the inclined plane 61 and resting on this inclined plane. The wedge 60 comprises a flat upper surface 63 on which the base of the mobile part 57 rests.

Consider direction A as the direction of transmission of the force between the movable element 33 and the pressure element 29, i.e. substantially the pressing direction. In said direction A the adjustment of the mobile part 57 is also but not exclusively carried out, therefore said mobile part 57 ? moved in said direction A by the wedge 60 which in turn slides on the inclined plane 61.

The wedge 60 can? be moved along the inclined plane 61 by means of suitable movement means 58, for example a screw which can be screwed in or unscrewed from a threaded through hole 64 formed in the movable element. The wedge 60 ? substantially moved in the direction C by said means 58 from the position of fig. 14a to the position of fig. 14b.

In this case, passing from the position of fig. 14a to the position of fig.

14b, the wedge 60 has traveled the inclined plane 61 upwards, causing a lifting of the movable part 57 from the position of fig. 14a to the position of fig. 14b.

The inclination of the inclined plane 61 ? such as to prevent the force acting in direction A from being transmitted to the means 58 by modifying the position of the mobile part 57.

The configuration of the adjuster 56 in FIG. 14a ? such as to bind only forces in the direction Al, since? in general, the pressing apparatuses generate a force only in this direction A1 and not ? necessary to refine the mechanism why? bind the force in the two directions of direction A.

The encumbrance of the wedge 60 in direction C? naturally smaller than the width of the seat 54, so that said wedge 60 can cover a certain stroke, even minimal, inside said seat 54 in direction C. It is clear that modifications can be made to the pressing apparatus described up to now and/or additions of parts, without thereby departing from the scope of the present invention as defined by the claims.

In the claims that follow, the references in brackets have the sole purpose of facilitating the reading and must not be considered as limiting factors as regards the scope of protection implied in the specific claims.

Claims (10)

1 . Pressing apparatus, comprising at least one pair of pressing elements (29, 31) aligned along a pressing direction (A), wherein at least one first pressing element (29) ? associated with means (32, 44) for movement along said pressing direction (A) and ? pushed towards a second pressure element (31) by at least one mobile element (33) and according to a thrust surface (34) defined on the mobile element (33), characterized in that between said mobile element (33) and said first element presser (29) ? positioned at least one calibrated shim (35) on at least a portion of said thrust surface (34). 2. Pressing apparatus according to claim 1, characterized in that said movable element (33) is a crossbar resting on said first pressure element (29) and connected to said movement means (32, 44). 3. Pressing apparatus according to claim 1, characterized in that said calibrated thickness (35) ? connected in a removable manner and by means of suitable fixing means (37) to said movable element (33). 4. Pressing apparatus according to claim 1, characterized in that said thrust surface (34) ? covered at least partially by a plurality? of plates (38, 39, 40) and said at least one calibrated thickness (35) ? positioned between at least one plate of said plurality? of plates (38, 39, 40) and said thrust surface (34). 5. Pressing apparatus according to claim 1, characterized in that said movable element (33) comprises two ends? (41, 42) arranged to the side of said first pressing element (29) and said second pressing element (31) and associated with said means (32) for moving the mobile element (33), said calibrated thickness (35) being positioned between said movable element (33) and said first pressure element (29) in a central region (43) of said thrust surface (34). 6. Pressing apparatus according to claim 1, characterized in that said movement means (44) are associated with a central area of the mobile element (33) located on a surface (45) opposite to the thrust surface (34) , said movable element (33) being provided with at least one pair of calibrated thicknesses (35) located in lateral areas (46, 47) of said thrust surface (34). 7. Pressing apparatus according to claim 1, characterized in that said movable element (33) ? connected at the ends? to respective supports (49, 50) positioned along guides (51, 52) for translation along said pressing direction (A) and comprises at said ends pins (48) inserted in said supports (49, 50) and able to allow the rotation of said movable element (33) with respect to said supports (49, 50), said movable element (33) being constrainable to each of said supports (49 , 50) through one or more? adjustment devices (56) configured to allow stable locking of the mobile element (33) in any position with respect to said supports (49, 50). 8. Pressing apparatus according to claim 7, characterized in that said adjustment device (56) comprises a movable part (57) configured to be inserted in a seat (54) of the movable element (33) and to accommodate at least one pin (55) housed in said movable part (57) and in a seat (53) obtained in said support (49, 50), said movable part (57) being configured to translate at least along said pressing direction (A) so substantially to vary the geometric position of the seat (54) where said pin (55) is inserted. 9. Pressing apparatus according to claim 8, characterized in that said adjustment device (56) comprises at least one wedge (60) cooperating with said movable part (57) to translate it in one direction or the other at least along said direction ( A) for pressing, said wedge (60) being associated with movement means (58) which allow it to be translated at least along one direction (C) substantially perpendicular to said pressing direction (A). 10. Pressing apparatus according to claim 9, characterized in that said wedge (60) comprises at least one inclined base surface (62) resting on an inclined plane (61) obtained in said seat (54) and an upper surface ( 63) on which rests said movable part (57) of the adjustment device (56).