Metal founding – Process – Shaping a forming surface
Patent
1989-11-17
1991-10-15
Rowan, Kurt
Metal founding
Process
Shaping a forming surface
164410, 164234, B22C 706
Patent
active
050565800
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for producing moldings, into whose interior is introduced a molding material mixture and, particularly for producing core boxes for core shooting, in which ventilating openings or vents are provided in the mold cavity and are provided with nozzles.
Although the present invention is especially directed to the production of a core box in which a core is produced from a corresponding core sand mixture, it can also be used in other similar processes.
BACKGROUND OF THE INVENTION
An important criterion for optimum core sand mixtures is, apart from a good surface of the casting and good core stability up to the time of casting, good disintegration of the blank following casting. This significantly influences the amount of cleaning to be carried out on the rough casting. Therefore what is sought consists of core molding material mixtures which, as cores after casting, have a maximum amount of burnt molding material (detachment from the casting inner wall) and ensure a rapid residual material disintegration from the casting during jolting.
Numerous modern, efficient core shooting machines are commercially available for the production of sand cores according to various core production processes. Known core production processes are the shell molding process (Croning process), the hot box process, the cold box process, the carbon dioxide solidification process and the SO.sub.2 process.
It is necessary in each of these processes, when introducing the sand mixture for the core, vents are available from which the air which must give way for core formation can escape. In certain other processes, even following core production, this is scavenged e.g. with carbon dioxide, a catalyst mist or CO.sub.2, e.g. in order to bring about its complete hardening.
The corresponding bores for venting purposes or for introducing the scavenging medium are now normally occupied by nozzles, which have cross-barred slits or small holes. The corresponding recesses for the nozzles are generally drilled, which involves additional working operations. As a core box can have 100 or more nozzles, so that the core can be correctly vented throughout or sand can flow into unfavourable positions, or the core box is filled in an adequate and uniformly compressed manner, said subsequent operation is very complicated and costly.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process of the aforementioned type making it possible to obviate this disadvantage and therefore significantly facilitating and reducing the cost of the production of core boxes.
According to the invention this problem is solved in that during the molding of the molded part (core member), particularly the core box, at least one insert is used, whose shape corresponds to the nozzle, said insert being removed after the molding of the core box and replaced by the nozzle.
Thus, in the present case, it virtually constitutes a duplicate of the nozzle, which is only used during the production of the core box. It is subsequently removed and replaced by the real nozzle.
The insert can e.g. be a material which automatically dissolves. However, preference is given to the insert being made from plastic or even metal. To remove the insert, it is connected to a pressure line, which can subsequently be used as a ventilating tube. If the pressure line is placed under the pressure of a pressure medium, then the insert is shot out of its seat, so that the nozzles can be readily inserted.
It is also possible to knock the insert out of its seat and consequently within the scope of the invention the insert has a shaped-on part.
According to another embodiment of the invention the insert has a frontal blind bore with an internal thread, into which can be screwed a mating threaded pin and by means of the latter the insert can be drawn out of its seat.
The temporary fixing of the insert to the molded part or the like takes place by bonding with a high-speed adhesive, or in certain cases in self-adhesive manner.
Both the process and
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Farley Walter C.
Pelto Rex E.
Rowan Kurt
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