EXTRUSION PRESS

Abstract: Direct or indirect extrusion press which comprises a container (20) that defines a chamber (19) to hold a billet (11) to be extruded, a ram (12), a die (14), a die holder (41), a base (13) and a shears (15) to shear heels (17) of the billets (11), the die (14) being capable of movement axial to the container (20) or viceversa, the container (20) defining at least two chambers (19) and being able to move in a plane perpendicular to the plane on which the axis of the chamber (19) and die (14) lies. Extrusion plant which comprises a press as described above and includes three stations that perform extrusion (19a), charging (19b) and the cleaning and readying of chambers (19c) respectively, the stations cooperating respectively with the chambers (19).

Description: This invention concerns a press device for extrusion of a metal billet according to the preamble of claim 1. The invention can be applied either to direct extrusion presses or indirect extrusion presses. Extrusion means here the plastic deformation of a metallic billet passed through an appropriate die, the extrusion being carried out by a ram or by the die, depending on the type of extrusion. Direct extrusion presses are known and are those in which the metal deformed by the thrust of a ram while passing through a die emerges in the direction of forward movement of the ram. Indirect extrusion presses are also known and are those in which the metal emerges in the opposite direction to the forward movement of the die. In the known systems of direct (Fig. 1) and indirect (Fig. 2) extrusion shown diagrammatically in the figures cited above and attached hereto for the purposes of clarification, it is necessary to arrange thereafter not only for an express and specific step of shearing the heel of the billet (Figs. 1d and 3c) but also for a specific step of withdrawing the ram (Figs. 1a and 2a) so as to enable a new billet to be introduced for extrusion. The withdrawal of the ram has to be such as will enable the new billet to be moved crosswise onto the axis of the extrusion chamber. The operations of shearing the heel of the previous billet, withdrawing the ram and introducing the new billet entail additional, considerable, non-productive times due to the stoppage and therefore a heavy operating cost. Moreover, as the ram itself has to position the billet first and then to extrude it in the state of the art, it is necessary, after the step of positioning and beginning to extrude the billet, to halt the thrust action momentarily, withdraw the ram to let out the air and then to restart the extrusion. This operation too is necessary in the state of the art and entails not indifferent downtimes and waste. Document US-A-3,240,046 discloses a metal extrusion press having a rotatable turret on which three containers are mounted. The turret is rotatable about an axis carried by a platen. The platen carries also a second rotatable turret which supports a pair of dies and a pair of discard shearing punches. In operation, said turrets are rotated in order to align a container and a die to a pressing ram. Meanwhile, loading and cleaning operations are carried out on the other containers. The invention tends to eliminate the downtimes cited above and to obtain limited times for changing the billet and shearing its heel, thus enabling a high rate of output to be achieved. This is achieved by a press device having the features disclosed in the characterising part of claim 1. The dependent claims describe advantageous forms of embodiment of the invention. According to the invention the container can move sideways and comprises three containment chambers having their axes parallel; a shears is provided which is suitable to shear any remaining heel of a billet in the direction of sideways movement of the container. The productive working cycle is substantially exactly the same as with traditional presses. According to the present invention, however, while one chamber is undergoing the extrusion step, an other chamber is being cleaned, readied and the other one charged with the next billet. Moreover, as the latter chamber is charged separately, the problem of withdrawal of the ram for expulsion of air does not arise. The three chamber are provided at equal distances apart on a circumference and can rotate on the axis of that circumference; the third chamber downstream of the extrusion position is employed for cleaning work, so that in the next position of introduction of a billet the containment chamber has already been cleaned and is ready to accept the billet. According to the invention, while the chamber is being moved from one position to another, the shears in cooperation with the die performs the shearing of the heel, which is free to drop independently. According to the invention while the chambers are being transferred from one working position to another, the container body comprising the chambers withdraws and a shears cooperates with the die in shearing the heel of the billet. The attached figures, which are given as a non-restrictive example, show the following:- Figs. 1 and 2 give diagrams of the various working steps of the state of the art; Figs. 3 to 7 show a form of embodiment of the invention. Figs. 1 and 2 give rough diagrams since the practical application to individual extrusion presses is a design problem. For the sake of simplicity, Figs. 1 and 2 and the other figures show the extrusion of solid sections, but are applicable correctly to complex and/or bored sections as well. Fig. 1 gives the various steps performed by an extrusion press with a direct cycle. The first step 1a provides for introduction of a billet 11 into a chamber 19 after a considerable axial withdrawal of a ram 12 so as to leave the necessary space for the sideways approach of the billet 11 to take up a position along the axis of the chamber 19. When the billet 11 has been inserted into the chamber 19 of a container 10 (Fig. 1b), the ram 12 is advanced and starts exerting its thrust, so that the material begins being extruded through a die 14, after which the ram 12 withdraws to let air out and then starts the actual extrusion step. When the ram 12 has ended its travel (Fig. 1c), a heel 17 of the billet forms within the container 10 and, to be eliminated, has to be sheared from the extruded product 16 by a shears 15. The shears 15 performs the shearing of the heel 17 after the ram 12 and container 10 or base 13 (Fig. 1d) have been distanced from the heel. Instead, in the event of indirect extrusion (Fig. 2) the procedure is substantially analogous since the ram 12 has to withdraw considerably (Fig. 2a) to enable the billet 11 to be introduced into the chamber 19. When the extrusion operations shown in Figs. 2b have been carried out, a bond is formed between the extruded product 16 and its heel 17, which is produced in this case too. The heel 17 has to be sheared (Fig. 2c) by an appropriate shears 15, which sunders it from the extruded product 16 after the die 14 has been moved away. After this operation the chamber 19 has to be cleaned and readied, and then a new billet 11 is inserted therein. As can also be seen just from the diagram used to show the working cycle of the direct or indirect extrusion presses, the state of the art entails long downtimes due to the shearing (positions 1d and 2c), to the introduction of the billet (positions 1a and 2a) and to the auxiliary operations and also involves an initial waste of time. As we said earlier, such waste of time is considerable in view of the slow movement of the ram, which cannot be displaced quickly and therefore causes very long times for its withdrawal and approach. These times are not reduced by the inclusion of traditional means to charge the billets. According to the invention the container 20 includes three chambers 19 and is able to rotate step by step about an axis of rotation 21. In such a case each position of the chamber 19 will comprise its own specialized equipment directly correlated with its momentary working function. The container 20 comprises three chambers 19 arranged, for instance, circumferentially about the axis of rotation 21; the third chamber 19c undergoes a cleaning and readying operation performed, for instance, by a cleaning means 30 while the other chambers 19a and 19b respectively performing the extrusion and charging carry out the specific tasks described. In this way a plant to accompany the press is obtained in which the whole cycle can be automated and the operator's task becomes an auxiliary control function. A charging means 29 may include a traversing carriage 35 positioned by a rapid displacement jack 36, on which is fitted a charging jack 34 that thrusts the billet 11 into the chamber 19 in its position 19b. The cleaning means 30 comprises a cleaning tool 33, which may also be capable of rotary movement and be actuated axially by a cleaning jack 32 that cooperates with the axis of the chamber 19 in its position 19c. The cleaning means 30 may act in the opposite direction to the direction of extrusion. The charging means 29 too may work in the same direction as, or in the opposite direction to, the direction of extrusion. The invention arranges that during the extrusion step at least two clamping jacks 34 actuate clamping wedges 23 with recessed brake shoes that act very close to the periphery of the chamber 19. The inclusion of the wedges 23 and the action of the clamping jacks 24 enable the clamping action to be restored continuously and to be kept very near to the periphery of the billet being extruded. This arrangement, which becomes possible owing to the special nature of the invention, enables lateral extrusions, which take place in the state of the art owing to the bending of the stiffening arms, to be avoided. The chambers 19 may comprise circumferential heated chambers 28 which serve to keep the chambers 19 at the required temperature. These heated chambers 28 may be heated with resistors which, in the case of a container 20 able to rotate in one single direction 40, are fed by a ring-type distributor. When the extrusion step in the first chamber 19a has been carried out, the container 20 passes from a working position 37 to a transfer position 38 and is removed from the die 14 by a required distance. In the embodiment shown in Figs. 3 to 7 the container 20 is displaced axially by a displacement jack 18. When the container is in the transfer position 38, the shears 15 advances and shears the heel 17 protruding from the die 14. A means 31 to discharge the heel 17 may be included in cooperation with the shears 15. Rotation of the container 20 is obtained by the action of a motor 25, which acts by means of a pinion 26 on a gear wheel 27 coaxial with the axis of rotation 21 and solidly fixed to the container 20. The die 14 is held by a die holder 41, which is capable of being moved by a die-change jack 22 to make possible an easy replacement of the die 14. According to the invention, therefore, the working times required for replacement and repairs are very short and, whether the extrusion is direct or indirect, enable the efficiency of the working cycles per unit of time to be increased considerably.

Claims: A press device for carrying out extrusion of a metal billet, comprising a container (20) rotatable about an axis (21) and provided with three chambers (19a, 19b, 19c) having their axes parallel, suitable for holding a billet (11) to be extruded whereby the three chambers are provided at equal distances apart on the circumference of the container and can rotate about the axis of the circumference, said device futher comprising a ram (12), a die (14), a die holder (41), a fixed base (13) and a shears (15) suitable for shearing a heel (17) of said billet (11), characterised in that said die (14), die holder (41) and shears (15) are assembled on said fixed base (13), and in that said container (20) is movable in a direction parallel to the extruding direction, the rotation of said container (20) about its axis (21) causing each of said three chambers sequentially (19a, 19b, 19c) to assume a position as an active chamber in which the longitudinal axes of said ram (12), said active chamber (19) and said die (14) are aligned to each other, so that while this active chamber is undergoing the extrusion step, the other two chambers can be presented to other operating positions and so that while the active chamber is moved from its position to another the shears shear the heel of the extruded billet in cooperation with the die. Press device according to claim 1, characterised in that said container (20) is provided, in the neighbourhood of the outlet of said billet (11), with recessed clamping wedges (23) actuated by clamping jacks (24) during the extrusion process, the wedges (23) being located near the periphery of the chamber (19). Press device according to anyone of the preceding claims, characterised in that it comprises a station for loading a billet (11) into one (19b) of said chambers and another station for cleaning and preparing another (19c) of said chambers. Press device according to claim 3, characterised in that said station for cleaning comprises at its front a cleaning tool (33) movable along the axis of said chamber (19c). Press device according to anyone of the preceding claims, characterised in that said shears (15) is able to shear said container. Press device according to anyone of the preceding claims, characterised in that the axial movement of said container (20) is caused by a displacement jack (18) connected to said base (13). Press device according to anyone of the preceding claims, characterised in that the rotation movement of said container is caused by a motor (25) carried by said base (13) and coupled to said container (20) by means of a pinion (26) and a gear wheel (27). Press device according to anyone of the preceding claims, characterised in that said die holder (41) is rectilinearly movable by means of a die-change jack (22) in order to enable said die (14) to be replaced.

Inventors: BENEDETTI, GIAMPIETRO, NONINI, GEREMIA
Applicants: DANIELI & C. OFFICINE MECCANICHE S.P.A.
Application year: 1988
Main classification: B21C23
IPC codes: B21C27, B21C23, B21C35