FIELD OF THE INVENTION

The present invention concerns a pressing apparatus, in particular an apparatus capable of developing high-pressure forces able to plastically deform a material being worked until it is reduced to the desired shape. The apparatus can be used, for example, for metalworking, for example for forging, molding, punching, shearing, but also for molding plastic materials, for forming ceramic products, or other.

BACKGROUND OF THE INVENTION

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

A general configuration of a known press allows to insert a component called a “mold” into a suitable housing, which in turn consists of two other parts called “mold” and “counter- mo Id”. The press has the task of reciprocally moving the “mold” and “counter-mold” as they close or open.

The operation of closing the mold and counter-mold against each other has the purpose of producing or working objects of different kinds, such as metal, plastic, ceramic or other objects.

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

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

• the base where the mold generally rests; this is the fixed part of the press;

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

There are mainly two operations that a press has to perform:

• exert pressure evenly distributed over the entire surface of the mold so that it is properly tightened and is not damaged;

• open and close the mold, then rest the mold on the counter-mold or vice versa, ensuring correct parallelism between said components.

A known pressing apparatus is described for example in document WO-A- 2018/039402.

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 in fig. 1 comprises a crosspiece 21, a base 22, means 23 for moving the crosspiece 21, for example hydraulic pistons, a counter mold 24 on which the crosspiece 21 rests and a mold 25 which in turn rests on the base 22.

The means 23 are positioned on the sides of the crosspiece 21 and pull the crosspiece 21 against the base 22 in order to reciprocally compress the mold 25 and the counter-mold 24.

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

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

• elastic defects or elastic structural failure;

• geometric defects or defects of assembly and manufacturing tolerances of the various components.

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

Both the crosspiece 21 and also the base 22 normally deform by thrusting more on the edges of the mold 25 and of the counter-mold 24 and the pressure is greater at the ends of the mold 25 and of the counter-mold 24, while it decreases in the center.

Therefore, the pressing apparatus 20 has the obvious problem of the non- homogeneous closing pressure of the mold 25 and the counter-mold 24. Even by stiffening both the crosspiece 21 and also the base 22, this problem would continue to arise and furthermore the weights of said components would increase, as would the production costs as well.

The pressing apparatus 26 also has problems with the bending of the crosspiece 21 and the base 22 when the means 27 drive the crosspiece 21 which thrusts the counter-mold 24 against the mold 25.

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

The geometric defects of known pressing apparatuses substantially derive from how the pressing apparatuses are constructed and from inevitable manufacturing errors, since a perfect manufacture is in fact impossible to achieve.

In relation to the configuration of the pressing apparatus 20 in fig. 1 , but the argument would also be the same for the pressing apparatus 26 in fig. 2 or any other configuration, in fig. 3a the crosspiece 21 with which the counter-mold 24 is integral is inclined by an angle a with respect to the base 22, consequently said counter-mold 24 is also inclined with respect to the mold 25 which is integral with the base 22.

This inclination by said angle a can be caused by construction errors and assembly errors.

Fig. 3b is a view of the pressing apparatus 20 in fig. 3a rotated by 90° with respect to a vertical axis, in which a second inclination by an angle b can be seen which, like the first, causes a lack of parallelism between the mold 25 and the counter-mold 24 at their interface.

Said undesired inclinations are particularly harmful in the case of the so-called presses called “Mold Testers”. The so-called “Mold Tester” presses are a subgroup of presses able to put the mold and counter-mold reciprocally in contact with each other so that an operator can evaluate the quality of the interface and correct any manufacturing defects of the mold and counter-mold.

It is therefore clear that a fundamental prerogative of so-called “Mold Tester” presses is to be themselves a parallelism reference between the crosspiece and the base because the parallelism reference is used to understand if the mold and counter-mold are parallel to each other or if they have to be modified in order to be so.

Another prerogative of so-called “Mold Tester” presses is to present the pressing unit, whether it is the mold and/or the counter-mold, to the operator, that is, they have the possibility of rotating with respect to a substantially horizontal axis in order to be able to examine the surface of the counter-mold and the mold that will come into contact with each other. These presses generally have a pair of uprights to which the crosspiece carrying the counter-mold is connected. The crosspiece is connected to the uprights by means of sliding supports and vertically to hinges which allow it to rotate with respect to a substantially horizontal axis.

The hinges allow to inspect the surfaces of the mold and the counter-mold, rotating the counter-mold after it has been suitably distanced from the mold. However, the hinges cannot remedy the geometric defects of the press, since they are not suitable for the transmission of the force generated by the means that move the crosspiece.

A known attempt to mitigate the elastic defects of known pressing apparatuses, for example the pressing apparatuses 20 and 26, is to give a convex shape to the crosspiece in the central contact zone with the counter-mold 24.

However, this solution is not very effective and increases the constructive complexity of the crosspiece and the pressing apparatus. Making a crosspiece with a precise convexity is in fact a very complicated operation and often does not provide the desired results.

Furthermore, the crosspiece equipped with convexity can be used substantially only for a certain nominal pressure, whereas if the pressure that the crosspiece has to exert is to be varied, problems arise in any case of non-homogeneity of the pressure applied and undesired bending of the crosspiece and of the base of the pressing apparatus.

There is therefore a need to perfect a pressing apparatus which can overcome at least one of the disadvantages of the state of the art.

In particular, one purpose of the present invention is to provide a pressing apparatus in which the typical disadvantages of known pressing apparatuses are eliminated or at least limited, in particular with regard to elastic defects, or elastic structural failure, mainly due to a non-uniform and non-homogeneous application of the pressure of the pressing elements that make up the pressing apparatus.

Another purpose of the present invention is to provide a pressing apparatus in which further defects typical of known pressing apparatuses are eliminated or at least limited, in particular with regard to geometric defects, or in particular assembly defects and manufacturing tolerances of the various components.

One purpose of the present invention is therefore ultimately the production of a pressing apparatus that can operate in a precise and reliable manner and with a uniform and homogeneous pressure exerted by the pressing elements that compose it, even when varying the pressure exerted by the pressing apparatus.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claim. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

In accordance with the above purposes, a pressing apparatus according to the present invention comprises at least one pair of pressing elements aligned in a pressing direction, wherein at least a first pressing element is associated with means for movement in the pressing direction and is thrust toward a second pressing element by means of at least one mobile element and according to a thrust surface defined on the mobile element.

According to one aspect of the invention, between the mobile element and the first pressing element there is positioned at least one calibrated shim on at least one portion of the thrust surface.

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

The present pressing apparatus can also operate in a precise and reliable manner and the use of at least one calibrated shim has several advantages, including simplicity of manufacturing, economy, ease of availability and the fact that it can be easily replaced with one that has a greater or lesser thickness when it is necessary to increase or decrease the closing pressure of the pressing apparatus.

Furthermore, using at least one calibrated shim has considerable advantages also in “Mold Tester” presses, which constitute a geometric reference for the molds that are tested in them. The mobile element can be a crosspiece resting on the first pressing element and connected to the movement means.

The calibrated shim can be connected to the mobile element in a removable manner and by means of suitable attachment means.

According to other aspects of the invention, the thrust surface can be at least partly covered by a plurality of plates and the at least one calibrated shim can be positioned between at least one plate of the plurality of plates and the thrust surface.

In some embodiments, the mobile element can comprise two ends disposed on the side of the first pressing element and the second pressing element and associated with the means for moving the mobile element; the calibrated shim can be positioned between the mobile element and the first pressing element in a central zone of the thrust surface.

The movement means could also be associated with a central zone of the mobile element located on an opposite surface with respect to the thrust surface; in this case, the mobile element can be provided with at least one pair of calibrated shims located in lateral zones of the thrust surface.

In some embodiments, the mobile element is connected at the ends to respective supports positioned along translation guides in the pressing direction and comprises, in correspondence with the ends, pins inserted in the supports and able to allow the rotation of the mobile element with respect to the supports; the mobile element is constrainable to each of the supports by means of one or more adjustment devices which are configured to allow a stable clamping of the mobile element in any position whatsoever with respect to the supports.

The adjustment devices contribute to correcting the geometric errors at the time the pressing apparatus is commissioned.

The adjustment device can comprise a mobile part configured to be inserted in a seating of the mobile element and to accommodate at least one pin housed in the mobile part and in a seating made in the support; this mobile part is configured to translate at least in the pressing direction in such a way as to substantially vary the geometric position of the seating where the pin is inserted.

The adjustment device can comprise at least one wedge cooperating with the mobile part to translate it in one sense or the other at least in the pressing direction; the wedge can be associated with movement means which allow its translation at least in a direction substantially perpendicular to the pressing direction.

Moreover, the wedge can comprise at least one base surface inclined and resting on an inclined plane obtained in the seating and a flat upper surface on which the mobile part of the adjustment device rests.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a schematic view of a first known pressing apparatus;

- fig. 2 is a schematic view of a second known pressing apparatus;

- figs. 3a and 3b are two schematic views that show geometric defects of the pressing apparatus of fig. 1 ;

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

- figs. 5a and 5b are two three-dimensional 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 another embodiment of the present invention;

- fig. 8 is a three-dimensional view of a mobile element of the pressing apparatus of fig. 7;

- fig. 9 is a three-dimensional view of the mobile element of the pressing apparatus of fig. 4 and/or fig. 7;

- fig. 10 is a three-dimensional view of the mobile element of fig. 9;

- fig. 11 is a view on a larger scale of a part of the mobile element of fig. 9 and fig. 10;

- fig. 12 is a three-dimensional view of a mobile element equipped with adjustment devices;

- fig. 13 is a larger scale view of a part of the mobile element of fig. 12; - figs. 14a and 14b are two views which schematically show the functioning of the adjustment devices.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be combined with, incorporated into, other embodiments without further clarifications.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

We will now refer in detail to the possible embodiments of the invention, of which one or more examples are shown in the attached drawings by way of a non-limiting illustration. The phraseology and terminology used here is also for the purposes of providing non-limiting examples.

With reference to the attached drawings, see for example figs. 4, 5a and 5b, a pressing apparatus 30a comprises at least one pair of pressing elements 29 and 31 aligned in a pressing direction A, wherein at least a first pressing element 29 is associated with means 32 for movement in the pressing direction A and is mobile toward a second pressing 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 the mobile element 33 and the first pressing element 29 there is positioned at least one calibrated shim 35 on at least one portion of the thrust surface 34.

As can be seen in fig. 7 and fig. 8, the pressing apparatus 30b also comprises at least one calibrated shim 35 on at least one portion of the thrust surface 34.

The first pressing element 29 can be for example a counter-mold, while the second pressing element 31 can be a mold resting on the base 36 of the pressing apparatus 30a.

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

The mobile element 33 can be a crosspiece resting on the first pressing element 29 and connected to the movement means 32.

The calibrated shim 35 can be removably connected to the thrust surface 34 by means of suitable attachment means 37, for example screws, bolts or suchlike. The calibrated shim 35 can be a sheet of metal, readily available on the market, it can be cut to the desired size and there is a wide range of thicknesses with differences even in the order of hundredths of a millimeter.

The thrust surface 34, as can be seen in figs. 5a and 5b, can be covered by a plurality of plates 38, 39, 40. The calibrated shim 35 will be positioned between at least one plate, for example the plate 39 of fig. 5a, of one of the plates 38, 39 and 40. The plates 38, 39, 40 can for example be screwed to the thrust surface 34. The plates 38, 39, 40 can partly or totally cover the thrust surface 34.

In the case of the apparatus 30b of fig. 7 and fig. 8, there are for example provided two calibrated shims 35 positioned between the thrust surface 34 and the plates 38 and 40.

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

When the mobile element 33 bends because it is pulled by the movement means 32, see fig. 6a, first a thrust is exerted where the calibrated shim 35 is placed, therefore in a central zone, subsequently, the bending also takes the mobile element 33 into contact at the sides of the pressing element 29. See in this regard the graph in which the trend of the pressure P is constant along the entire extension of the thrust surface 34.

The calibrated shim 35 has the advantage that it can be easily replaced with a thicker one when it is necessary to increase the closing pressure of the pressing apparatus.

In fig. 6b, for example, if it is provided to exert a pressure PI greater than the pressure P exerted in fig. 6a, it is possible to replace the calibrated shim 35 with a calibrated shim 35’ with a greater thickness, which still guarantees a uniform distribution of pressure on the pressing element 29, as indicated in the diagram.

In combination with or as an alternative to what has just been described, it would also be possible to provide to use multiple calibrated shims 35 located one on top of the other in order to obtain a desired overall thickness. The use of the calibrated shim 35 is therefore advantageous compared to the use of a crossbar with convexity, because it is easily replaceable and easily installed according to the needs of the pressing apparatus 30a or 30b, which are in particular to be able to reciprocally close the pressing elements 29 and 31 , for example mold and counter-mold, at different pressures and correctly press even pressing elements of different sizes.

The use of at least one calibrated shim 35 assumes considerable importance when referring to “Mold Tester” presses, because such presses are able, more than any other type of press, to close molds, that is, a mold against the counter mold, with the most diverse geometry and always at different pressures, contrary to a production press that often acts on a single type of mold.

Therefore, in the case of mold tester presses, the solution that provides to use at least one calibrated shim 35 allows to limit geometric defects and has the same advantages that can be found for the pressing apparatuses described, that is, ease of replacement and simplicity of manufacturing or retrieval on the market in order to reduce costs, increasing the performance of this type of pressing apparatus.

For the pressing apparatus 30b shown in fig. 7, similar considerations regarding the advantages deriving from the use of calibrated shims 35 apply.

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

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

The calibrated shims 35 can for example be positioned between the plates 38 and 40 and the thrust surface 34. The plates 38 and 40 will then be attached to the thrust surface 34 by means of screws, bolts or suchlike.

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, in order to compensate for the bends that 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 appropriately positioned calibrated shims.

The mobile element 33 could be equipped with pins 48 that allow it to be used even in the so-called “Mold Tester” presses, see for example fig. 8.

These pins 48, of which only one is visible in fig. 8, allow the mobile 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 seatings made in the supports 49 and 50, and the mobile element will be able to rotate about an axis B. This axis B is a substantially horizontal axis and allows the rotation of the mobile element 33 so as to be able to make clearly visible the thrust surface 34 or the surface of the pressing element 29 which will engage on the surface of the pressing element 31, if the pressing element 29 is made integral with the mobile element 33.

Basically, the position of the mobile element 33 of fig. 9 can be identified as an inspection position, while that of fig. 10 can be identified as a pressing position.

In the pressing position, although the pins 48 are resistant, it is generally not advisable for them alone to be stressed by the pressing force.

Furthermore, also during the pressing, it is important that the mobile element 33 does not move by rotating around the pins 48 in direction B.

In order to clamp the position of the mobile element 33 with respect to a certain inclination, for example the inclination that it has in the pressing position of fig. 10 but also in 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 shown in fig. 11, a first seating 53 can be made aligned with a second seating 54 made in the mobile element 33. A pin 55 can be inserted in these seatings which clamps the mobile element 33 with respect to the supports 49 and 50.

Basically, the pin 55 makes the mobile element 33 and the supports 49 and 50 integral, and also deals with transmitting the force to the mobile element 33.

Once the pin 55 engages in the mobile element 33, blocking the rotation, depending on how the whole system is built and compatibly with the inevitable manufacturing errors and tolerances, geometric errors may occur, as in figs. 3a and 3b.

According to the present invention, it is provided to use one or more adjustment devices 56, see fig. 12 and fig. 13, configured to allow a stable clamping 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.

The adjustment devices 56 help to correct the geometric errors when the pressing apparatus 30a, 30b is commissioned.

Basically, each of the adjustment devices 56 allows to modify the geometric position of the seating 54 where the pin 55 is inserted.

The adjustment device 56 is based on the concept of a wedge or cam. The adjustment device 56, see fig. 13, comprises a mobile part 57 able to slide inside the seating 54 made in the mobile element 33. The mobile part 57 can slide, upward or downward in the seating 54, by the amount sufficient to compensate for manufacturing and/or assembly errors, so it is a matter of a few millimeters.

At least one through hole 59 is made in the mobile part 57, where the pin 55 will be inserted.

The adjustment device 56 also comprises a wedge 60 able to slide on an inclined plane 61 obtained at the base of the seating 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.

Let us consider direction A, that is, substantially the pressing direction, as the direction of transmission of the force between the mobile element 33 and the pressing element 29. The adjustment of the mobile part 57 is also but not exclusively carried out in direction A, therefore the mobile part 57 is moved in 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 that can be screwed or unscrewed from a threaded through hole 64 made in the mobile element. The wedge 60 is substantially moved in direction C by the 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 up the inclined plane 61, causing the mobile part 57 to lift from the position of fig. 14a to the position of fig. 14b.

The inclination of the inclined plane 61 is such as to prevent the force that acts in direction A from being transmitted to the means 58, modifying the position of the mobile part 57. The configuration of the adjustment device 56 in fig. 14a is such as to constrain only forces in sense Al, since generally pressing apparatuses generate a force only in such sense Al and it is not necessary to refine the mechanism in order to constrain the force in the two senses of direction A.

The overall size of the wedge 60 in direction C is naturally smaller than the width of the seating 54, so that the wedge 60 can travel a certain, even minimal, stroke inside the seating 54 in direction C.

It is clear that modifications and/or additions of parts may be made to the pressing apparatus as described heretofore, without departing from the field and scope of the present invention as defined by the claims. In the following claims, the sole purpose of the references in brackets is to facilitate reading: they must not be considered as restrictive factors with regard to the field of protection claimed in the specific claims.