Patent US 3,936,251

This press comprises a frame structure, an unloading station on one side of said frame structure, a mold, a cross member extending over said frame structure and movable in relation thereto between a molding position in which the upper portion of the mold is vertically aligned with the lower portion of the mold, and an unloading position in which said upper mold portion is vertically aligned with said unloading station. The cross member is mounted in cantilever fashion at one end to a support having a vertical axis and is adapted to pivot about this vertical axis and slide along said support. The press is intended notably for vulcanizing tires and affords a considerable reduction in the mold loading and unloading time while being more reliable in operation. PAC BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to presses, notably for vulcanizing tires, of the type comprising a frame structure, an unloading station located on one side of said structure; a mold having a lower portion supported by said structure and an upper portion, a cross member from which said upper mould portion is suspended, said cross member extending over said frame structure and being movable in relation thereto between a moulding position in which said upper mold portion is vertically aligned with the lower mold portion and an unloading position in which said upper mold portion is vertically aligned with the unloading station. 2. Description of the prior art Most modern vulcanizing presses are equipped with means for automatically loading the crude tyre to be vulcanized, the cured tyre being subsequently unloaded by means of a roller conveyor. As a rule, the vulcanization cycle takes place automatically and the major fraction of the cycle time is devolved to the tyre curing process, and the mould opening time, crude time, crude tyre loading time, cured-tyre unloading time and mould re-closing time constitute but a small fraction of the total cycle time (about eight percent under the most propitious circumstances). Since the operator entrusted with the vulcanization operation must also suply crude tyres to several presses, there is provided in front of each vulcanization cavity (as a rule two such cavities are provided in each press) a stocking cradle adapted to receive a crude tyre substantially at any time during the vulcanization cycle. Thus the operator is alllowed a certain flexiblity as far as the loadinng time is concerned, a feature not obtainable if the tyre were to be mounted directly on the loader. With this system, one tyre is undergoing the vulcanization step while another tyre is waiting on the loader and a third tyre is placed on the stocking cradle by the operator. On the other hand, a cured tyre is unloaded either before or while loading a crude tyre, according to the press design. Thus, in a first type of known press in which the cured tyre is discharged before starting the fitting of the crude tyre into the lower mould portion, there is provided, for loading crude tyres to be vulcanized, a loader supported by a hanger pivoted to the frame structure of the press and adapted, with the assistance of a hydraulic or pneumatic cylinder and piston actuator and clamps (internal or external clamps, according as the tyre is a conventional one or a radial-ply one), to pick up the crude tyre to be vulcanized from the stocking cradle, hold this tyre waiting during the vulcanization and unloading of the tyre being vulcanized, then position the crude tyre to be vulcanized in vertical alignment with the lower mould portion before releasing said tyre and moving back to pick up another crude tyre from the stocking cradle. The known presses of this first type further comprise, for unloading the cured tyres, at least one roller discharge conveyor adapted to be moved and positioned by suitable means under the cured tyre previously lifted with the upper portion of the mould up to a predetermined level above the lower mould portion, and arranged with a view to allow the cured tyre to slide down to another conveyor constituting a general cured-type collecting system for a series of presses. In a second known type of presses of the kind currently referred to as "slide back" presses, wherein the loading operation and the unloading operation take place simultaneously, the tyre loader is connected with the press closing cross member and this member has two degrees of liberty. In other words, the cross member can move along a vertical path and along a horizontal path. With this arrangement, while the mould is closed and a tyre is undergoing the vulcanization process, the loader can pick up a crude tyre automatically from the stocking cradle and hold it waiting. At the end of the vulcanization step, the press is opened and the cross member is caused to move horizontally or substantially horizontally with the upper portion of the mould, and also with the cured tyre, to a position located above a roller conveyor where the cured tyre is released. During this horizontal or substantially horizontal movement of the cross member, the loader connected with said cross member is moved to a position in which it is in vertical alignment with the press cavity (i.e., the lower portion of the mould) so that a crude tyre can be positioned in turn into this mould portion. Hitherto known presses of the two above-described types however have various inconveniences. Thus, notably, in the first case there is a likelihood of not properly removing or clearing out the discharge conveyor during the mould closing step, for example in cae of electric or pneumatic failure in the means controlling the movement of said discharge conveyor; it is obvious that in this case very serious damages would result. Moreover, the loading and unloading times are considerably longer since these two operations take place in succession. In the second case, the loading time and unloading time are shorter than in the first case, but still relatively long due to the considerable inertia developing in the press. Moreover, owing to the specific design of the assembly, a constant vertical movement of the cross member is necessary, whatever the vertical dimension of the mould, and this also causes a loss of time when the press is operated for vulcanizing relatively small tyres. PAC SUMMARY OF THE INVENTION It is therefore the main object of the present invention to provide a press for vulcanizing tyres which provides the advantageous features of simultaneous loading and unloading, but without the inconveniences characterizing known presses of said first and second types. More particularly, the present invention is directed to provide a press which is particularly reliable in operation and capable of reducing considerably the loading and unloading times. To this end, the invention provides a press of the type referred to above, characterized in that the cross member is mounted at one end in cantilever fashion to a support having a vertical axis, and so arranged that it can both pivot about the vertical axis of said support and slide therealong. According to another feature characterizing this invention, the loader is connected to said cross member for movement therewith in such a manner that, when said cross member is in it moulding position, said loader is vertically aligned with the loading station, and that, when said cross member is in its unloading position, said loader is vertically aligned with the lower portion of the mould so as to load same, in a manner somewhat similar to that observed in known presses of the second type mentioned hereinabove.