APPARATUS FOR THE HOT-CHAMBER DIE CASTING OF NON-FERROUS ALLOYS

Abstract

An apparatus for the hot-chamber die casting of non-ferrous alloys essentially consists of a press (115) for the closing/opening of a mould (110, 111) and an injection group (112) comprising a pump body (102) immersed in a pot (124) of the molten alloy and in which an injector piston (116) slides, an actuator (108) connected to the injector piston (116), and a gooseneck formed of in the pump body (102) and ending with a heated extension (103) provided with a nozzle (104) for the connection to the mould (110, 111), two hydraulic jacks (114) being secured between the injection group (112) and the press (115) which is fixed, the injection group (112) being divided into a stationary bottom portion and a top portion movable on sloped guides (109) parallel to the longitudinal axes of the extension (103) and of the hydraulic jacks (114), the pot (124) being mounted on horizontal rails (120) and the hydraulic jacks (114) being secured to the pump body (102).

Claims

1. An apparatus for the hot-chamber die casting of non-ferrous alloys, consisting essentially of: a) a mould made up of two semi-moulds, b) a press for closing/opening said mould, c) a base carrying said press, d) an injection group comprising: i) a pump body partially or totally immersed in a molten alloy contained in a pot, ii) an injector piston that slides in said pump body, iii) an actuator mounted on a crossbar above said pot and reversibly connected to said injector piston to drive it into a reciprocating motion, iv) a gooseneck formed in the pump body, v) a heated extension arranged at an external end of said gooseneck and provided with a nozzle for the connection to the mould, said nozzle being located higher than an opposite end of said extension such that the latter has a slope towards the gooseneck, and e) at least two double-acting hydraulic jacks arranged symmetrically with respect to the extension and secured, with a slope equal to the slope of the extension, between the pump body of the injection group and the portion of said press closest thereto, said apparatus being characterized in that the press is fixed and the injection group is mobile along sloped guides arranged on said base, said sloped guides being parallel to and preferably coplanar with the longitudinal axes of the extension and of said hydraulic jacks, and in that the injection group is divided into a top portion, comprising the actuator and the crossbar, and a bottom portion comprising the pump body the injector piston and the pot, the latter being mounted on horizontal rails.

2. An apparatus according to claim 1, characterized in that the pump body is restrained to the pot through elastic supports, and it is hung through brackets to top horizontal guides that are integral with the crossbar.

3. An apparatus according to claim 2, characterized in that it further includes bolts that guarantee the coaxiality between the injector piston and the actuator during the normal operative phases and upon opening allow the brackets to slide along the top horizontal guides.

4. An apparatus according to claim 2, characterized in that it further includes an automatic or semi-automatic loader, preferably of the Cartesian type, for the rapid replacement of the injector piston when it is disengaged and out of axis with respect to the actuator, upon sliding of the brackets along the top horizontal guides.

5. An apparatus according to claim 1, characterized in that it further includes a device that moves the pot along the horizontal rails until it is disengaged from the top portion of the injection group, upon disengagement of the injector piston from the actuator and of the hydraulic jacks at one end thereof.

6. An apparatus according to claim 1, characterized in that it includes two or more injection groups connected to a same mould so as to inject therein same or different alloys, simultaneously or at successive times.

7. An apparatus according to claim 1, characterized in that the press is arranged with a horizontal or vertical axis.

8. An apparatus according to claim 3, characterized in that it further includes an automatic or semi-automatic loader, preferably of the Cartesian type, for the rapid replacement of the injector piston when it is disengaged and out of axis with respect to the actuator, upon sliding of the brackets along the top horizontal guides.

9. An apparatus according to claim 2, characterized in that it further includes a device that moves the pot along the horizontal rails until it is disengaged from the top portion of the injection group, upon disengagement of the injector piston from the actuator and of the hydraulic jacks at one end thereof.

10. An apparatus according to claim 3, characterized in that it further includes a device that moves the pot along the horizontal rails until it is disengaged from the top portion of the injection group, upon disengagement of the injector piston from the actuator and of the hydraulic jacks at one end thereof.

11. An apparatus according to claim 4, characterized in that it further includes a device that moves the pot along the horizontal rails until it is disengaged from the top portion of the injection group, upon disengagement of the injector piston from the actuator and of the hydraulic jacks at one end thereof.

12. An apparatus according to claim 2, characterized in that it includes two or more injection groups connected to a same mould so as to inject therein same or different alloys, simultaneously or at successive times.

13. An apparatus according to claim 3, characterized in that it includes two or more injection groups connected to a same mould so as to inject therein same or different alloys, simultaneously or at successive times.

14. An apparatus according to claim 4, characterized in that it includes two or more injection groups connected to a same mould so as to inject therein same or different alloys, simultaneously or at successive times.

15. An apparatus according to claim 5, characterized in that it includes two or more injection groups connected to a same mould so as to inject therein same or different alloys, simultaneously or at successive times.

16. An apparatus according to claim 2, characterized in that the press is arranged with a horizontal or vertical axis.

17. An apparatus according to claim 3, characterized in that the press is arranged with a horizontal or vertical axis.

18. An apparatus according to claim 4, characterized in that the press is arranged with a horizontal or vertical axis.

19. An apparatus according to claim 5, characterized in that the press is arranged with a horizontal or vertical axis.

20. An apparatus according to claim 6, characterized in that the press is arranged with a horizontal or vertical axis.

Description

[0028] These and other advantages and characteristics of the die casting apparatus according to the present invention will be clear to those skilled in the art from the following detailed description of two embodiments thereof with reference to the attached drawings in which:

[0029] FIGS. 1 and 2 show a schematic view in longitudinal section of a prior art apparatus in a position of closed mould (with full cavity) and detachment of the carrot, respectively, as described above;

[0030] FIGS. 3 and 4 show a schematic view in longitudinal section of a first embodiment of a hot-chamber die casting apparatus according to the present invention in a position of closed mould (with full cavity) and detachment of the carrot, respectively;

[0031] FIG. 5 shows a schematic view in cross section of said apparatus;

[0032] FIG. 6 shows a partial schematic view in longitudinal section of said apparatus in the position for the replacement of the injector piston;

[0033] FIG. 7 shows a partial schematic view in longitudinal section of said apparatus in the position for the cleaning of the crucible and/or the maintenance/replacement of the molten alloy pump sub-group; and

[0034] FIG. 8 shows a schematic view in longitudinal section of a second embodiment of an apparatus, with vertical closure of the mould and two injection groups.

[0035] With reference to FIGS. 3 to 5, there is seen that a hot-chamber die casting apparatus according to a preferred embodiment of the present invention comprises a base 130 carrying a closure group 115 of the two half-moulds 110 and 111, that enclose the cavity 106 of the mould, which is with horizontal attitude and guides as in the common cold-chamber apparatuses. The axis of the extension 103 is instead inclined on the horizontal, similarly to the current hot-chamber apparatuses, and the axis of the molten alloy pump and of its actuator 108 is vertical.

[0036] The body 102 of the pump is constrained and elastically supported, by means of supports 122 of known type, by the structure of the pot 124 in which it is immersed and, in the injection phase, is coaxially connected to the actuator 108 of the injector piston 116. If necessary, the body 102 can be free to slide on top horizontal guides 118, integral with the crossbar 113 which carries the actuator 108, to which it is hung by means of two brackets 119, symmetrical with respect to the axis of the actuator 108. During the injection, the brackets 119 serve to create a closed loop of forces between the pump and its actuator.

[0037] The injection group 112 is free to slide on two sloped guides 109 (preferably of the rolling type) disposed at the top of the parts of the base 130 which flank the injection group 112. The guides 109 are parallel to the inclined axis of the extension 103 and to the axes of the adherence jacks 114, and even preferably coplanar with said axis of the extension 103 and with the axes of the jacks (plane with trace b-b of FIG. 5), so as not to transmit moments with respect to the point of intersection between the axes of the nozzle 104 and of the carrot 105 and with respect to the extension 103.

[0038] The travel on the guides 109 can be limited to the maximum elongation at break of the carrot 105, with adjustable and elastic mechanical stops not shown. Notwithstanding the fact that the travel along the guides 109 must guarantee the tight adherence of the nozzle 104 to the mould 110/111, the aforesaid elastic stops may also serve to establish the virtual center of said travel, which in any case can be otherwise determined by any of the methods known in the art, such as position transducers connected to the jacks 114.

[0039] The operation of the production cycle is similar to the most up-to-date techniques for small and medium castings, namely closing of the mould, injection and compacting of the casting, solidification of the same, cooling of the casting and return of the injector piston, opening and filling of the injector cylinder, extraction of the casting, cleaning and lubrication and cooling of the mould, closing of the mould, etc.

[0040] While the previous technique provided for the carrot tear at each cycle, the current production technique, thanks to the progress in temperature control, requires that the adherence of the extension to the mould remains, reduced during the opening of the mould, and that it is interrupted only in in the event that the solidification of the casting propagates to the nozzle. This eventuality cannot be avoided in case of anomaly in the temperature control, and in this case the junction between extension and mould would prevent the continuation of the production cycle, therefore the apparatus must be equipped anyway for tearing the carrot.

[0041] FIG. 4 represents the apparatus upon performing the tear, thanks to the adherence jacks 114 which intervened with sufficient force and stroke by moving the pump body 102 away from the press 115 and sliding the injection group 112 along the inclined guides 109, thus dragging the pot 124 along the horizontal rails 120, such motions being compatible thanks to the elastic supports 122. Jacks, pump body, extension, nozzle and carrot create a closed loop of forces.

[0042] In this way, the heaviest part of the apparatus, consisting of the press 115 and the mould 110/111, remains stationary, while only the injection group 112, easily slidable, much less heavy and bulky, is moved.

[0043] Furthermore, the injection group 112 is divided into a top portion comprising the actuator 108 mounted on the crossbar 113 provided with the guides 118, and a bottom portion comprising the pump body 102 which contains the injector piston 116 and is in turn contained in the pot 124.

[0044] FIG. 6 shows the apparatus in the position for the replacement of the injector piston 116, this position being reached thanks to the action of the jacks 114 but only after having given consent to the trespassing motion by opening the bolts 123 (FIG. 5) which serve to guarantee the coaxiality between the piston 116 and the actuator 108 during the normal operating steps and the possible tearing of the carrot. With the bolts 123 open and interlocked with the actuator 108, the jacks 114 push the pump body 102 which by means of the brackets 119 slides on the guides 118 dragging the pot 124 therewith, thus moving the piston 116 out of axis with respect to the actuator 108.

[0045] Unlike what happens in the carrot detachment phase, shown in FIG. 4, in this case the top portion of the injection group 112 remains stationary since the actuator 108 is disengaged from the piston 116 and therefore the action of the jacks 114 on the pump body 102 is transmitted only to the pot 124 through the supports 122 and its cover 117. Note that the pump is supported mainly by the cover 117 of the pot 124 through the elastic support system 122, so that the sliding along the guides 118 is smooth since these guides are practically unloaded given that the system weighs on the rails 120 but is directed by the guides 118, which determine the position of the pump. This allows the quick replacement of the injector piston 116 with total safety by means of an automatic or semi-automatic loader, preferably Cartesian and dedicated, not shown.

[0046] Similarly, FIG. 7 shows the apparatus in the position for the cleaning of the pot 124 and/or the safe maintenance or replacement of the molten alloy pump sub-group, with a weight even of several thousand kg, the operation being made easy and safe by the elastic suspension 122 of the pump sub-group to the casing of the pot 124. Also in this case, the top portion of the injection group 112 remains stationary since the actuator 108 is disengaged from the piston 116, but the pot 124 is moved by any prior art system, not shown, since the required displacement is greater than the stroke of the jacks 114 which are therefore disengaged at one of their two ends (for example at the pump end in FIG. 7) so that the pump sub-group can move back along the rails 120 with the brackets 119 which disengage from the guides 118.

[0047] FIG. 8 represents an apparatus with vertical closure of the mould, provided with two injection groups that are able to inject two identical or different alloys into the mould, simultaneously or in succession with each other. This makes it possible to produce castings of dimensions that are unimaginable with current techniques, even bimetallic or polymetallic, through dedicated injection groups that could even be more than two.

[0048] It is clear that the embodiments of the apparatus according to the invention described and illustrated above are only examples susceptible of numerous variations. In particular, the elements have been described in a schematic way since it is within the normal ability of a person skilled in the art to replace them with other technically equivalent ones, for example the double-acting hydraulic jacks 114 can be replaced by similar actuators capable of performing the same functions of adherence of the mould 110/111 to the nozzle 104, of detachment 107 of the carrot 105 and of retraction of the piston 116 for its replacement.