Casting tool and core-making machine

Abstract

The invention relates to a casting tool for the production of castings, particularly for the production of cores (90) for sand castings, comprising a supporting device consisting of a first and a second supporting unit (10, 20, 50, 60) capable of being moved in a joining direction (2) toward each other, and comprising at least two mold elements (30, 40), of which a first mold element (30) is attached to the first supporting unit (10, 20) and a second mold element (40) is secured to the second supporting unit (50, 60), which mold elements (30, 40) each have a mold recess (33, 43), which mold recesses (33, 43) in the mold elements (30, 40) together define the shape of at least one casting core to be produced (90) when the first and second mold elements (30, 40) bear against each other.According to the present invention, one of the supporting units (10, 20) has a first peripheral frame (20) that surrounds the mold element (30) attached to said supporting unit (10, 20), and the frame (20), as multi-segment frame, is composed of at least two frame segments (22, 24, 26) joined together by positively effective securing means.The use thereof as a very simply and quickly produced core-casting tool.

Description

TECHNICAL FIELD AND PRIOR ART[0001]The invention relates to a casting tool for the production of castings, in particular cores for sand castings, pressure die castings, and gravity die castings. A generic casting tool comprises a supporting device comprising first and second supporting units which can move toward and away from each other in a joining direction. Furthermore, a generic casting tool of such kind comprises at least two mold elements, of which a first mold element is mounted on the first supporting unit and of which a second mold element is mounted on the second supporting unit. The first and second mold elements each comprise mold recesses oriented toward each other, the mold recesses of the first and second mold elements jointly defining the shape of at least one workpiece to be produced such as a casting core, when the first and second mold elements bear against each other and the mold is thus closed. Furthermore, the invention relates to a core-making machine compris...

AI Technical Summary

Benefits of technology

[0007]It is an object of the invention to develop a generic casting tool in such a ...

Problems solved by technology

This seal is of major importance because in an insufficiently sealed system, not all parts of the sand core are sufficiently contacted by gas during gas treatment so that the sand grains do not adequately bind to each other to form a unitary and solid sand core.

The necessity of producing this seal between the two halves of the molding box is substantiated by the fact that the mold elements cannot be positioned accurately enough in relation to each other so that they cannot bear against each other in a completely gastight manner along the parting line of the mold.

The restricted capability of the first and second mold elements to be accurately positioned is largely due to the imprecise tolerance compliance of the molding boxes.

Apart from the above-described casting production of the molding boxes, production of the latter in the form of welded structures is also known from the prior art, which likewise gives rise to a problem involving production accuracy, since the individual components of the welded molding box become warped to a large extent by thermal stresses occurring during welding, thus necessitating an expensive post-machining step, which however does not result in a degree of precision that would produce high-quality sealing of the mold cavity across the mold elements.

In addition to their inadequate dimensional stability, cast or welded molding boxes also suffer from the drawback of being extremely heavy.

The weight of these molding boxes is frequently so great that they cannot be stored in high racks but must be stored in a usually very restricted floor space.

Another disadvantage associated with previous designs is that it is very difficult to align the mold elements in relation to each other.

Since the mold elements come into contact with each other only when the molding boxes of the bottom and top mold elements also bear against each other, it is scarcely possible to align the mold elements in relation to each other.

The quality of the cores produced is thus not always ideal.

It is preferred, however, that the frame has a free internal area in the manner explained below, which free internal area is significantly larger than the base area of the mold elements so that the frame does not perform a guiding function.

With such a design, the frame cannot perform any guiding function as specified.

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