DIRECT MECHANICALLY-OPERATED EXTRUSION PRESS

Abstract

There is described an extrusion press (1) of a metal billet, comprising a die (3), a punch (2) able to push the billet through the die (3), and a container (4) of the billet upstream of the die (3). Said extrusion press (1) further comprises a screw (5) with which the punch (2) is integral, able to engage a nut screw (6) provided in the extrusion press (1). At least one electric motor (7) drives the reciprocal movement of the screw (5) and nut screw (6), thus causing the translation of the punch (2) in the extrusion direction.

Claims

1. An extrusion press of a metal billet, comprising a die, a punch able to push the billet through the die and a container of the billet upstream of the die, wherein a screw which the punch is integral to, able to engage with a nut screw in the extrusion press, at least one electric motor driving reciprocal movement of the screw and of the nut screw thus causing the movement of the punch in the extrusion direction.

2. The extrusion press according to claim 1, wherein the nut screw is driven to rotate about an axis of the screw, corresponding to the movement direction of the screw, by said at least one electric motor.

3. The extrusion press according to claim 1, wherein the nut screw is fixed and the screw is driven to rotate about an axis of the screw, corresponding to the movement direction of the screw, at least by said at least one electric motor.

4. The extrusion press according to claim 1, wherein a plurality of horizontal screws which respective nut screws engage with, thus causing the movement in the extrusion direction of a vertical plate which the punch is integral to.

5. The extrusion press according to claim 1, wherein there is a lubrication unit able to insert lubricating fluid between the screw and the nut screw.

6. The extrusion press according to claim 1, wherein said at least one electric motor comprises a rotor integral with the nut screw, and a stator integral with a base.

7. The extrusion press according to claim 1, wherein said at least one electric motor comprises planetary motors able to engage with a crown integral to the nut screw.

8. The extrusion press according to claim 1, wherein a block which provides a cylindrical inner surface of a cylindrical cavity on which a cylindrical outer surface of the nut screw slides.

9. The extrusion press according to claim 8, wherein an interstice is provided between said cylindrical outer surface and said cylindrical inner surface, able to accommodate lubricating fluid to facilitate the sliding of the nut screw in the block.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] These and other features of the present invention will become more apparent from the following detailed description of an exemplary practical embodiment thereof, shown by way of non-limitative example in the accompanying drawings, in which:

[0017] FIG. 1 shows a partially cross-sectional side view of an extrusion press according to the present invention;

[0018] FIG. 2 shows a sectional view according to line II-II in FIG. 1;

[0019] FIG. 3 shows a block of the sectional view in FIG. 2;

[0020] FIG. 4 shows a body of the sectional view in FIG. 2;

[0021] FIG. 5 shows a cylinder of the sectional view in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

[0022] An extrusion press 1 able to transform a metal billet profile by plastic deformation (extrusion) comprises a punch 2 able to push the billet through a die 3.

[0023] The billet is supported and guided by a container 4 which limits the expansion thereof during the push through the die and is placed between the punch and the die and guides the billet towards the die.

[0024] Punch 2 is integral with a screw 5 (see circle A in FIG. 1 in which the threading of screw 5 is depicted on enlarged scale).

[0025] Screw 5 engages a nut screw 6 which substantially is an annular-shaped body with an inner threaded surface.

[0026] Said nut screw 6 is driven to rotation about an axis E of screw 5 by one or more electric motors mechanically connected thereto. FIG. 1 depicts an annular-shaped electric motor 7 alone.

[0027] Said electric motor 7 comprises a rotor 71 integral with the nut screw 6 and a stator 72 integral with a base 8 by a block 9.

[0028] The nut screw 6 includes a cylindrical outer surface 64 able to slide on a cylindrical inner surface 91 of a cylindrical cavity 93 of block 9.

[0029] An interstice 94 is provided between said cylindrical outer surface 64 and said cylindrical inner surface 91, which is able to accommodate lubricating fluid to facilitate the sliding of body 6 in block 9.

[0030] Body 6 further comprises an annular portion 65 (FIG. 1) which abuts against block 9, like a portion of rotor 71, thus axially blocking the body 6.

[0031] The extrusion press 1 further comprises a shear 10 able to separate the non-extruded end portion of the billet (referred to as a discard) after the extrusion, such as described in International Patent Application WO-2017103828, for example.

[0032] A cylindrical bar 11 connects the container 4 of the billet with block 9. Such a connection is made by a screw and a nut screw and is electrically operated. The electrically driven screw-nut screw function aims at moving the billet container 4 along axis E.

[0033] Moreover, the extrusion press 1 preferably but not necessarily comprises a lubrication unit able to insert lubricating fluid between screw 5 and nut screw 6 in order to limit the friction and thus the energy expenditure of the electric motor 7.

[0034] With regard to the operation, motor 7 rotates the nut screw 6, which allows the translation of screw 5 along axis E due to the engagement thereof.

[0035] During the extrusion, the nut screw 6 rotates so as to cause the displacement of screw 5, and therefore of punch 2, towards the container 4 in which the billet is accommodated (to the right, looking at FIG. 1).

[0036] Once in contact with the billet, punch 2 pushes the billet through die 3, thus causing the plastic extruded deformation thereof, i.e. generating a profiled element.

[0037] Once the extrusion has been complete, motor 7 reverses the rotation of the nut screw 6, causing screw 5, and therefore punch 2, to retract, thus returning to a configuration like that depicted in FIG. 1.

[0038] Advantageously, the push of punch 2 is caused by an electric motor which directly converts the driving torque thereof into axial force by screw-nut screw motion transmission means without the aid of hydraulic means, i.e. the possible pressurization of hydraulic means does not generate any force which contributes to the required extrusion force.

[0039] Preferably, there are between 40 and 60, even more preferably 50 threads engaged in the engagement of screw 5 and nut screw 6.

[0040] Preferably, the surface engaged in said engagement is between 1 m.sup.2 and 1.5 m.sup.2, even more preferably about 1.38 m.sup.2.

[0041] The aforesaid sizes cause a specific load ranging between 1 and 1.5 kg per square millimeter, preferably of 1.3 kg per square millimeter.

[0042] The maximum feeding speed of cylinder 5 preferably is between 25 and 35 mm/second, preferably 30 mm/second, with a rotation speed preferably being between 25 and 35 revolutions per minute, preferably 27 revolutions per minute corresponding to 0.45 revolutions per second.

[0043] The return speed of the cylinder obviously is greater (without a load), preferably between 550 and 650 mm/second, preferably 600 mm/second, with a rotation speed preferably between 800 and 1000 revolutions per minute, preferably 900 revolutions per minute corresponding to 15 revolutions per second.

[0044] Alternatively, instead of motor 7, there may be a toothed crown on which two or more planetary motors are engaged, the purpose of which is the rotation of the aforesaid crown directly fixed to the nut screw 6.

[0045] Advantageously, the screw-nut screw extrusion system allows a reduced volume of the press, increased cleaning, lower maintenance costs and reduced energy costs.

[0046] The push generated by this mechanical system is sufficient for the extrusion of any metal material without the interposition of a compressed fluid and of the complex hydraulic circuits required therein.

[0047] Alternatively, it may be provided that the nut screw 6 translates along axis E with the punch 2 integral therewith, and the screw 5 rotates, thus feeding and pushing the punch forwards, with which it is integral.

[0048] The same above-described screw-nut screw pushing system is also applicable with horizontal screws (e.g. four in number), with which respective nut screws are engaged, which move a vertical plate with which the punch is integral, along axis E. This includes the possibility for the nut screws to rotate-translate on the screws, or alternatively for the screws to rotate in order to feed the nut screws which are integral with the vertical plate.