The invention relates to a shooting head for a core shooter for shooting foundry cores or molds, the shooting head having an opening at its inlet end for selective connection to a filling device immersing with a discharge end or outlet member into the shooting head and predetermining the filling level, or to a clamping head serving to sealingly apply compressed air, and a shooting plate arranged at its outlet end and comprising shooting nozzles.
Core shooters with shooting heads of the kind under discussion have been known from practice for a long time. For example, reference may be made to DE 41 28 952 C1.
However, within the scope of an automatic production of core packs, the known shooting heads of the described kind are problematic. Depending on the core being shot, differences in shooting weights from 60 kg to 1 kg occur, the shooting heads being normally capable of receiving core sand in a quantity of at most 70 kg. Regardless of the size of the core being shot, the outside dimensions of the shooting heads are however predetermined, in particular in the automatic production of core packs. This means that the shooting heads in the core shooter must be exchangeable regardless of the cores being shot. Consequently, in the case of shooting very small cores, there is a large supply of sand and binding agents in the interior of the shooting head, the small shooting weight causing only a small throughput of core sand and binding agents. In the presence of large supplies of sand in the shooting head, and in particular as a result of the temperature inside the shooting head, which is about 35.degree. C., this small throughput leads to an ageing of the binding agent that is mixed with the core sand, so that cores shot with a very small throughput of sand often lack adequate strength.
Furthermore, it is necessary that the compressed air required for the shooting penetrate through the entire sand supply within the shooting head, so that a rather considerable compression occurs already in the shooting head, which complicates the shooting of the cores, or makes it even impossible when lumps form in the region upstream of the nozzles.
It has already been proposed in DE 41 28 952 C1 to alleviate the problem of penetrating the sand supply with compressed air inside the shooting head to the extent that a filling device or an outlet member thereof immersing into the shooting head fills the shooting head to a certain, predetermined filling level, thereby filling the shooting head only in part. Furthermore, the filled-in molding sand is flattened more or less by a closing flap of the outlet member, so that the core sand being within the shooting head is quasi evenly distributed. Nonetheless, also in this instance it is necessary to fill in a considerable quantity of core sand, even for shooting very small cores, since the filling with only a small amount of core sand would not supply all shooting nozzles with an adequate amount of sand. A complete filling of the shooting head still leaves, even after a flattening, the aforesaid ageing problem on the one hand and, on the other, the problem of penetrating the total supply of core sand in the shooting head with compressed air, so that the risk of unwanted preliminary compressions within the shooting head is incurred likewise in this instance.
In its not-yet published German Application P 42 08 647.7-24, applicant has already proposed itself a further solution to the problem with respect to the risk of a preliminary compression occurring inside the shooting head. To avoid an unwanted preliminary compression within the shooting head, a device is provided for generating a turbulence or for an even distribution of the compressed air flowing from the air supply into the shooting head, the device being a so-called streamline filter with slot-shaped passages. However, the ageing problem is thereby not solved.
Even a synopsis of the prior art known, on the one hand, from DE 41 28 952 C1 and relating to a filling device, and the turbulence of the compressed air required for the shooting by means of a streamline filter as claimed on the other hand in German Application P 42 08 647.7-24, will be able to alleviate at most, but will not solve the problem that arises in particular with the shooting of very small cores both with respect to the ageing of the binding agent within the shooting head and with respect to an unwanted preliminary compression within the shooting head.
It is therefore the object of the present invention to describe a shooting head for a core shooter for shooting foundry cores or molds, which is also suitable in particular for shooting very small cores.