EP2995446B1

EP2995446B1 - Press and process for deforming metal pieces

Info

Publication number: EP2995446B1
Application number: EP15184429.7A
Authority: EP
Inventors: Giuliano Baglioni
Original assignee: Automazioni Industriali Srl
Current assignee: Automazioni Industriali Srl
Priority date: 2014-09-09
Filing date: 2015-09-09
Publication date: 2018-12-05
Anticipated expiration: 2035-09-09
Also published as: ES2713239T3; EP2995446A1

Description

FIELD OF THE INVENTION

The present invention relates to the field of presses, and in particular the field of hot presses of metal pieces such as billets and the like, for making elements having one or more surface deformations, or holes with variable depth and possibly passing through the whole piece.

KNOWN PREVIOUS ART

It is known in the art to make engraved or bored elements by housing metal semifinished starting pieces, such as for example billets, into a mould and then inserting, into such a mould, core pins or punches in controlled way that allow making one or more surface deformations or holes.
Such core pins are known to be hydraulically controlled, preferably through a cylinder/piston arrangement, since this arrangement is deemed the more suitable to ensure powers needed to carry out the piece deformation.
For example, the so-called toggle-lever presses (knuckle joint presses) are known, wherein a piston acts on the hinge point between connecting rod and crank of a respective connecting rod and crank arrangement, and wherein such a piston is hydraulically driven, for example through a hydraulic jack, the connecting rod controls the core pin movement and the crank is hinged to the machine frame.
In general hydraulic drives, in particular those applied to common toggle-lever presses, not only involve a degree of complexity and bulk of the whole machinery, but neither allow precisely adjusting the position of the core pin, or punch, and thus the shape of the final piece, except for the presence of a mechanical stop. It is therefore complex to precisely perform one or more holes or surface deformations in the work piece.
In particular, albeit in the hydraulically driven toggle-lever presses it is known to manually adjust the travel, or however the law of motion, of the connecting rod carrying the core pin or punch, through for example the displacement of the hinging point of the crank to the machine frame in dedicated predefined seats, such adjustments, besides being setting time consuming, do not allow precise adjustment of such a travel, since they consist of discrete displacements and not necessarily precisely compliant with the desired processing.
It has to be further considered that the thermodynamic characteristics of the oil, or in general of the liquid employed for operating the hydraulic press, can vary with time, for example even within a single day. Therefore, in view of the preceding, in response to the same command, the press movement can show variations over time, and thus errors, in component displacement.
It is clear thus to the field technician that pieces possibly manufactured in succession by a press of the hydraulic type herein mentioned can have holes or surface deformations with slight differences in size and shape one from another, due to the substantial impossibility of precisely and repetitively controlling the travel and speed of the hydraulically driven piston. In the event the finished pieces have to comply with very reduced tolerances, an inspection of such finished products is needed, with possible rejection of defective ones.
Such operations obviously entail time and resource wastes.
Furthermore, because of inaccuracies due to the afore reasons, the devices of the known art do not ensure a precise repetition of operations for deforming the billet in subsequent cycles, whereby the resulting pieces do not feature mutually homogeneous characteristics, with apparent drawbacks.
In addition, working inaccuracies on pieces also affect the life of moulds that are subjected to wear due to the sliding of the metal material compressed in the mould and stressed by the core pin.
Lastly, it has to be observed that the toggle-lever presses of the known art frequently operate with several toggle arrangements and respective core pin or punch per every single mould, so that to make several holes or surface deformations at the same time on every piece. In this case, means of the known art for simultaneously controlling the movement of several core pins through hydraulic drives are thus even more complex, in addition to have remarkable weight and bulk.
JP H07-195197 discloses a toggle-lever machine for punching, bending and cutting a sheet.
Object of the present invention is the implementation of a press for making surface deformations or holes on a billet or similar metal semifinished product, that overcomes the problems of the known art.
In particular, object of the present invention is the implementation of a press of the afore mentioned type that is cheap and allows at the same time a high level accuracy machining.
Other object of the present invention is the implementation of a press for making surface deformations or holes on a billet, or similar metal semifinished product, that ensures a high level repeatability of the piece in subsequent manufacturing cycles. Further object of the present invention is the implementation of a press for making surface deformations or holes on a billet, or similar metal semifinished product, that ensures a precise adjustment of the position of the core pin with respect to the mould.

SUMMARY OF THE INVENTION

These and other objects are achieved by the present invention by means of a press according to claim 1 and a respective operation process according to claim 7. Preferred aspects are denoted in the dependent claims.
According to the invention a press for deforming, and in particular for surface deforming and/or boring, metal pieces having the shape of billets or similar semifinished products, comprises at least one mould for the metal piece, and at least one deforming core pin, or punch, that can be reversibly and at least partially inserted into the mould to deform the metal piece. The core pin is arranged on a ram movable along a first axis, and such a ram is connected through a connecting rod to a movement element reciprocating at least axially along a second axis incident to the first axis. Advantageously, the second movement element is electrically driven. Thanks to the present invention, a simple and accurate control of the core pin position can be carried out through a system being moreover compact. The described system further allows an effective power transmission to the core pin (or pins), that therefore is able to carry out the deformation of the metal piece so that to make an opening, surface deformation or hole, on the same.
Moreover, the electric drive allows exerting high level control over the position of the movement element and thus of the core pin, so that homogeneous pieces in subsequent machine operating cycles can be shaped.
Thanks to this, also the mould lubrication system can operate more effectively, being able to work correctly and with constant behavior in different and subsequent operations of the press.
According to the invention, also the mould lubrication system is electrically driven and controlled. In particular, according to the invention the timing and amount in which the lubricant has to be fed to the mould during the operations of material deformation inside the latter can be controlled, preferably by a closed-loop control, depending on the position of the core pin and/or the second axis.
The Proprietor found that the moulds of the presses according to the present invention have a service life up to 6 - 8 times longer than the moulds of the known art.
According to the present invention, a crank connects the movement element and the connecting rod, through a shared hinging constraint, to a bearing whose position can be adjusted, so that to substantially implement a toggle.
However, with respect to conventional toggles, as mentioned, the bearing is movable, preferably along at least one third axis, to allow the ram kinematics and dynamics to be precisely adjusted. Such a movement is preferably further obtained through an electric drive.
Thanks to this, the main movement operations of the press can be carried out by the first movement element whereas, through the operation of the adjustable bearing, precise adjustment operations of the travel of the ram carrying the core pin or punch can be carried out.
Moreover, as mentioned, several core pins can operate on a single mould. Thanks to the present invention every single core pin can be adjusted precisely and independently so that to make a correct deformation on the piece inside the mould, typically a perforation or surface deformation, in a repeatable way over time.
In particular, the speed profile with which the core pin operates can be accurately controlled, i.e. the core pin speed can be adjusted instant by instant during the path towards the mould and inside the same.
According to a characteristic aspect of the present invention, the movable bearing has a first tilted surface, whereas an electric motor controls the movement of at least one second tilted and sliding surface, which is engaged with the first tilted surface, so that to precisely, and with small displacements, adjust the position of the movable bearing and thus, due to the described kinematic system, the position of the core pin. According to another aspect of the present invention, the core pin displacement can be controlled upon preset programs. Alternatively, or in addition to such core pin displacement programs, one or more sensors can detect the position of one or more elements such as the ram, the movable bearing, etc., in order to perform a closed-loop control on the core pin position.

BRIEF DESCRIPTION OF THE FIGURES

Referring to the enclosed figures, an exemplary and not limitative embodiment of the present invention is now presented, in which:

figure 1 is a partial sectional view of the drive mechanism of a core pin of a press according to the present invention;
figure 2 is an enlarged view of a detail of figure 1;
figure 3 is a side view of the mechanism of figure 1, with a detail in partial section of the mould and core pin;
figure 4 is a front view of a press according to the present invention with the mechanism of figure 1;
figure 5 is a sectional plan view along the plane A-A of figure 4.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION

Referring to the embodiment of the present invention shown in the figures, a press 1 for deforming metal pieces, typically the so called billets or similar semifinished products, comprises one or more moulds 3 inside which the metal pieces are shaped, for example engraved or bored pieces.
The mould 3 typically comprises two portions 3a, 3b, at least one of which movable to selectively open and close the mould. In the shown embodiment, referring particularly to figures 3 - 5, the press has a fixed lower portion 3a of the mould 3 and a movable portion 3b integral with a carriage 15 axially movable along guides 16 in a direction towards/away from the lower portion 3a of the mould. Also the drive of the carriage 15 is electrically controlled.
Therefore, generally speaking in the press 1 there are one or more core pins, or punches 2, to be forcedly inserted into the mould 3, partially or wholly, in order to plastically deform the billet, thereby making respective surface deformations or bores, for example through bores, into the same.
Referring particularly to figures 1 - 3 a core pin, or punch 2, is visible as integrally mounted on a ram 4 whose motion is generally a translation along a first axis A1. Typically, when the press 1 is arranged in an operative configuration, such an axis A1 (especially visible in figure 1) is arranged horizontally, albeit the possibility of mounting the press 1 so that the aforesaid axis A1 is vertical or oriented according to any direction selected upon the operative needs the press 1 has to meet, is not excluded.
Such a ram 4 is therefore an element of the press 1 slidingly mounted in a respective seat or on a specificguide that is operated in reciprocating translatory motion in order to insert and release the core pin 2 in the mould 3, the core pin 2 being integrally constrained, as mentioned, typically at one end thereof in a single piece or through proper constraints to said ram 4.
It has to be observed that, albeit a detail of a press provided with a single core pin 2 mounted on a single ram 4 is herein shown, any other arrangement of such a press providing the presence, for example, of one or more core pins mounted on the same ram or more rams provided with one or more respective core pins, still falls in the protection scope herein applied.
For example, in the plan view of figure 5 a first typology of ram 4 mounting a single core pin 2, i.e. the typology of ram shown in detail in figures 1 - 3, and a second typology of ram 4a carrying two core pins 2a, 2b, can be observed.
In addition the press 1 has a movement element 5, typically a slider, generally moving with reciprocating rectilinear motion along a second axis A2 tilted with respect to the axis A1, and thus incident thereto. In the embodiment herein shown, the tilt of such an axis A2 is equal to about 90 degrees, albeit other tilts are obviously possible.
In the shown embodiment it has to be observed that the tilt of the axis A2, with respect to the axis A1, slightly changes over time in operative condition, so as to allow the movement element 5 complying with the movement of the core pin along the axis A1, and in particular of the hinge 9, and avoiding jams. In other words the axis A2, along which the movement of the movement element 5 occurs in operative condition, is slightly swinging, in a controlled way.
In general, alternately the movement element 5 can be made through any tool known in the art that is able to give a predefined force along at least one rectilinear axis A2. The movement element 5, as it will be better defined in the following, is indeed driven through a convenient actuator in order to provide, albeit indirectly, a thrust to the ram 4 and thus to allow the latter to apply a predefined force along the afore mentioned axis A1.
In the herein shown implementation of the present invention a connecting rod 6, i.e. a substantially rod-shaped component designed to be subjected to a roto-translation during the operation of the press 1, operatively connects the movement element 5 to the ram 4. In particular, in the embodiment shown in the figures, the connecting rod 6 is hinged at the ends thereof to the ram 4 and to the movement element 5, respectively.
However, the use of other constraints is not excluded, in particular between the connecting rod 6 and the movement element 5, such as for example simply a rest constraint. In the same manner the connecting rod 6 could be constrained to the ram 4, and/or to the movement element 5, according to at least one rotation constraint with a possible translation component due to possible clearances made among the pieces.
Generally, the connecting rod 6 constrains, or at least operatively connects, the movement element 5 to the ram 4 so that a movement of the ram 4 along the first axis A1 corresponds to a movement of the movement element 5 along the second axis A2 and, thus, a force applied to the movement element 5 along the axis A2 is transmitted to the ram 4 and therefore to the core pin 2, along the first axis A1. The movement element 5 is electrically controlled in its own reciprocating movement thanks to an electric drive preferably comprising an electric motor, for example of brushless type, for example of the typology known in the art such as torque motors, albeit other electric drives can be used as well.
Various embodiments of such a drive, and especially of the kinematic system in charge for the motion transmission from the electric motor to the aforesaid movement element 5, are possible.
In the herein shown embodiment the movement element 5, in the form of a slider translatable along the axis A2 in a preferably swinging way as mentioned above, is integral to a worm 7 screwing along a seat 14 that is made as a threaded sleeve or hole (nut screw) at least partially surrounding the worm 7, and rotated by a first electric motor M1. Clearly for the field technician, the rotation of the seat 14 causes a translation along the second axis A2 of the worm 7 and the first movement element 5 connected thereto. The change in the rotation way of the threaded seat 14, for example caused by the change in the rotation way of the motor M1, naturally causes the translation in the opposite way of the movement element 5 so as to implement a reciprocating rectilinear motion of the latter along such a second axis A2.
As mentioned, it has to be observed that the use of an electric drive to cause the reciprocating motion of the movement element 5, and thus of the ram 4 and the core pin 2, allows an extremely precise and accurate control/adjustment of both kinematic and dynamic conditions of the core pin 2 itself in its motion inside the mould 3. The press 1 also has a crank 8 to operatively and functionally connect the core pin 2 to a bearing 10 whose position, as it will be seen, is preferably and advantageously adjustable along at least one third axis A3 of the press 1. Such a crank 8, in the present invention herein shown, is at least rotatably constrained at one end thereof to the afore mentioned bearing 10 and is also at least rotatably constrained at its other end to the same constraint, in this case the latter being in common and present between the movement element 5 and the connecting rod 6. Specifically, as visible in the figures, the crank 8 is hinged at one end thereof to the hinge 9, that in turn constrains the connecting rod 6 and the movement element 5 one to another. It has to be noted that such constraints between the crank 8, the connecting rod 6 and the movement element 5 can have clearances in order to allow just very little translations among such components.
The bearing 10 could be integral with the press 1, so that to serve as an additional guide for the ram 4 and limit the stresses imposed to the afore described kinematic system, so that to implement a conventional toggle.
However, according to the invention, the position of the bearing 10 can be adjusted, i.e. it is movable, preferably with a reduced degree of freedom so that, in addition to the afore mentioned structural function, it can allow a further adjustment of kinematics and dynamics of the respective core pin 2. In particular, the bearing 10 is preferably movable in a controlled way along at least one third axis A3, this axis being defined by a suitable seat or guide of the frame of the press 1 and being preferably rectilinear and coincident with, or at least parallel to, the first axis A1.
As it will be clear to the person skilled in the art, it has to be noted that the position adjustment of the movable bearing 10 is aimed to allow accurate adjustments of the applied force and the travel run by the core pin 2, and that such an adjustment can be carried out before or during translationally driving the core pin 2, since the respective movement element 5 is driven, that causes the plastic deformation of the billet in the mould 3. The position of the bearing 10 of the crank 8 is adjustable via a movable bearing 10 electrically controlled in its own movement, i.e. through an electric actuator for example constituted by a brushless electric motor of torque type, and by a respective kinematic system for transmitting the motion from the motor drive shaft to the bearing 10 itself.
Specifically, in the invention herein shown, referring in particular to figure 2, the drive responsible for the adjusted movement of the bearing 10 comprises a worm 11 rotatable thanks to the action of a second electric motor M2. The worm 11 reciprocatingly controls, depending on its rotation way, the translation of at least one first wedge-shaped body provided with a tilted surface 12a, having a sleeve-like portion in turn threaded (nut screw) and at least partially surrounding the worm 11. The thread of the sleeve of the body provided with the first tilted surface 12a couples (meshes) with the thread of such a worm 11, so that such tilted surface 12a axially translates along the axis of the worm 11. Such a first tilted surface 12a further couples by interference and reciprocally slides with a second tilted surface 10a belonging to the movable bearing 10 and being tilted in a way opposed to the tilt of the tilted surface 12a. Specifically, the first surface 12a slides with respect to the second surface 10a so that, according to known principles of the tilted plane, an axial translation of the movable bearing 10, in a direction typically perpendicular to the axis of the worm 11, corresponds to a relative sliding between the surfaces 12a and 10a along the aforesaid third axis A3.
The constraint between the two surfaces 12a and 10a can be of simple rest. However, such a solution allows the displacement of the movable bearing 10 in a single direction, i.e. the thrust direction of the first surface 12a with the second surface 10a. Thus, preferably the first surface 12a and the second surface 10a are coupled through a carriage-track system. In particular, in the embodiment shown herein, the first surface 12a has a groove not shown in the figures inside which a projection 13, integral to the second tilted surface 10a, can be coupled in a constrained way so as to slide along a single direction.
However, other solutions are possible. For example, the second surface 10a could have a groove and the first surface a projection. Alternatively, wheels on one of the two surfaces could be constrained so as to slide along a path defined on the other surface, etc.
In the shown embodiment, once a tilt angle α of the first tilted surface 12a has been defined with respect to the axis A3 for the movement of the movable bearing, such an angle α is preferably comprised between 45° and 90°, and even more preferably between 60° and 90°. In the embodiment of the present invention shown in the figures, the angle α is equal to about 78 degrees.
The Proprietor noticed how for such angles there is an effective force transmission between the tilted surfaces 12a and 10a.
Moreover, for angles wider than 45°, the travel of the movable bearing 10 is shorter than the travel of the first tilted surface 12a with respect to the worm 11, thus making easier to carry out small displacements of the mentioned movable bearing 10 and thus obtain a precise adjustment of kinematic and dynamic conditions upon which the ram 4, and thus the core pin 2, act. Moreover it is apparent that for angles close to 90°, as far as it can be achieved such a precision that very small displacements of the movable bearing 10 can be made, this would require a very high travel of the first tilted surface 12a.
The embodiment of the present invention herein shown has thus proven to be a good compromise among efficiency, bulk and accuracy of the system for motion transmission between the first tilted surface 12a moved under control of the motor M2, and the second tilted surface 10a kinematically connected to the core pin. Furthermore, in order to ensure better precision and higher effectiveness of the displacement imposed to the movable bearing 10, a movable body is equipped with a pair of first surfaces 12a and 12b and the movable bearing 10 is provided with a respective pair of second surfaces 10a and 10b. The first surfaces 12a and 12b can be reciprocally moved closer or away one another, so that to act on the respective second tilted surfaces 10a and 10b and thus cause a translation of the movable bearing 10 in the direction denoted as A3.
In the present invention, the worm 11 has two thread typologies 11a and 11b being counterwise one another. The thread 11a can for example be a right-handed thread, whereas the thread 11b can consequently be a left-handed thread (or vice versa). In general, the two thread typologies 11a and 11b each couple with a respective tilted surface 12a or 12b, so that a displacement of the tilted surfaces 12a and 12b in a way opposite one to another corresponds to a rotation of the worm 11 in a single way. During the use of the press 1, according to the particular embodiment herein depicted, after adjusting the position of the bearing 10 of the crank 8, the electric motor M1 controls the translation displacement of the movement element 5. Specifically, the electric motor M1 controls the rotation of the seat 14 and thus, by means of the coupling of the respective threads, the translation of the screw 7 carrying integrally the movement element 5 along the axis A2.
As it is apparent for the field technician, if the movement element 5 moves at constant speed along the second axis A2, the ram 4 would move at a speed variable over time, depending on the angle taken by the connecting rod 6 with respect to such an axis A2, for example.
It is therefore possible programming the electric motor M1 so that to enforce to the movement element 5 such a speed profile to ensure a constant speed, or alternatively a predefined speed curve, of the ram 4 and thus the core pin 2, in their translation along the first axis A1. In general, the electric motor M1 can be programmed so that the speed profile is deemed optimal for every single core pin 2 that has to interact with the given metal piece contained inside the mould 3.
Due to the constraint, imposed by the connecting rod 6, between the movement element 5 and the ram 4 (and the core pin 2 integral thereto) the ram 4 translates along the first axis A1 with the core pin 2 that can be inserted into the mould 3 in a controlled manner.
Furthermore, the second electric motor M2 can precisely adjust the position of the core pin 2, simultaneously with the action of the first electric motor M1 or, preferably, when the motor M1 is not operative for moving the movement element 5. In the embodiment of the invention herein shown, when required, the electric motor M2 controls the rotation of the worm 11, so as to move the first tilted surfaces 12a, 12b closer or away one another. Due to the afore described constraint, thanks to the opposed tilted surfaces 10a, 10b the bearing 10 is provided with, a movement of the movable bearing 10 along the axis A3 corresponds to such a motion.
Such a motion causes, due to the constraint imposed by the crank 8, a displacement even if reduced of the movement element 5 along the second axis A2 that, in turn and due to the connecting rod 6, displaces the ram 4 and correspondingly the core pin 2 connected thereto.
It has to be observed that the operation of the electric motors M1 and M2 can be controlled by an automatic controller known in the art, depending on preset programs. Alternatively, or in addition, to such a controller, sensors can detect the position of one or more elements such as the ram 4, the movable bearing 10, the movement element 5, the screw 7, etc.
In this case, through a closed-loop control (feedback), the position of the core pin 2 can be controlled depending on data detected by the mentioned sensors.
In addition, the electric drive of the core pins 2 allows phase shifting the movement of the core pins, specifically delaying or advancing the movement of one core pin with respect to another.
The Proprietor noticed how also the small phase shift of few milliseconds between the operation of a first core pin and the subsequent operation of a second core pin, causes considerable variations to the quality of the finished product, since the phase-shift could not have been controlled so carefully with the machines of the known art. The electric motor M2, and in general an electric drive in charge for the movement of the movable bearing 10 of the crank 8, has proven to be particularly effective in carrying out an accurate adjustment of the position, and especially of kinematic and dynamic conditions, of the core pin 2, whereby the Proprietor believes that there can be considerable advantages also in innovative embodiments of a toggle-lever press in which the electric motor M2, or any other electric drive, is in charge for the adjustment of the position of the movable bearing 10 of the crank 8 of the same toggle, also in a conventional toggle-lever press having non-electric main drive (i.e. equivalent to the motor M1), but for example hydraulic or pneumatic.
Furthermore, as mentioned, by adjusting the tilt of the first and second tilted surfaces, the ratio between the travel of the body provided with the afore said first surface 12a and the travel of the movable bearing 10 can be adjusted. As a result, with a high tilt of the first tilted surface 12a, errors in positioning the latter become negligible errors of the movable bearing. In other words, if for example the first tilted surface has an angle of 85°, an error of 1 cm in positioning the first tilted surface 12a along the respective screw with respect to the intended position, becomes a positioning error of the core pin of 1 cm / tan (85°), i.e. lower than one millimeter. Therefore it is not excluded that a second non-electric motor M2, for example a hydraulic one, although subjected to positioning errors, can carry out a sufficiently precise adjustment of the position of the bearing 10 and, thus ultimately, of the core pin 2, thanks to the described system that allows reducing the positioning error.

Claims

Press (1) for deforming at least one metal piece initially having the shape of a billet or similar semifinished product, comprising at least one mould (3) for said metal piece and at least one deforming core pin (2) that can be reversibly and at least partially inserted into said mould (3) to plastically deform said metal piece, said core pin (2) being arranged on a ram (4) movable along a first axis, said ram (4) being connected through a connecting rod (6) to a movement element (5) reciprocating at least axially along a second axis incident to said first axis, said movement element (5) being electrically driven, wherein a crank (8), constrained at one end to a respective bearing (10), is constrained at least freely to rotate at its other end to said movement element (5) and said connecting rod (6), at the constraint between said movement element (5) and said connecting rod (6), in order to define a toggle arrangement, wherein the position of said bearing (10) of the crank (8) is adjustable, through an electric drive, so as to at least translate in a controlled way along a third axis, wherein said crank bearing (10) comprises a couple of second tilted surfaces (10a, 10b), and an electric motor controls the movement of a couple of first tilted surfaces (12a, 12b) which are engaged in a sliding manner with said couple of second tilted surfaces (10a, 10b), characterized in that, two wedge-shaped bodies provided with said first tilted surfaces (12a, 12b), having a sleeve-like portion in turn threaded and at least partially surrounding a worm (11) are provided and driven by said rotatable worm (11) having a first and a second thread (11a, 11b), said first and second threads (11a, 11b) being counterwise one to another and both couplable with one first tilted surface (12a, 12b) of said couple of said first tilted surfaces, so that the rotation of said worm (11) makes said first tilted surfaces (12a, 12b) go closer or away one another.
Press (1) according to claim 1, wherein said third axis is parallel to, or coincident with, said first axis.
Press (1) according to any one of the preceding claims, wherein said movement element (5) comprises a slider moving with reciprocating rectilinear motion and hinged to one end of said connecting rod (6), and said press (1) is a toggle-lever press.
Press (1) according to one of the preceding claims, wherein said movement element (5) comprises a thread that can be operatively coupled to a complementary threaded rotating element operable by an electrically-driven motor.
Press (1) according to claim 4, wherein said thread of said movement element (5) is a square thread.
Press (1) according to one of the preceding claims, comprising a lubrication circuit comprising at least one lubrication channel fluidically connected to said mould (3), and at least electric pressurizing means for a lubricating liquid.
Process for making a metal piece from billets or similar semifinished products, through a press (1) according to one or more of the preceding claims, comprising the step of:
a) externally shaping said billet in said mould (3);

b) plastically deforming said billet through the reversible insertion of said core pin (2) in said mould (3);
wherein the path of said core pin (2) towards said mould (3) and inside said mould is controlled by an electric drive operating on said movement element (5), which in turn operates said core pin through a connecting rod (6), wherein said step a) in turn comprises the steps of:
a1) carrying out a generic positioning of said core pin through a first electric motor;

a2) starting a second electric motor so as to carry out a precise adjustment of the position of said core pin (2).
Process according to claim 7, wherein said step b) comprises adjusting, in a controlled way, the movement start time of a first core pin (2) with respect to the phase-shifted movement start time of an additional and different core pin (2).
Process according to claim 7 or 8, wherein before and/or after said step a) and/or before and/or after said step b), the press (1) carries out the additional step of:
c) lubricating said mould (3) through a lubrication circuit comprising at least one lubrication channel fluidically connected to said mould (3), and at least electric pressurizing means for a lubricating liquid, depending on the position of said core pin (2) along said axis A1, and/or depending on the mould opening.