GB2086781A - Core support - Google Patents

Abstract

A core support for casting practice is provided with an attachment surface (4) applicable by means of an adhesive layer to a core consisting of core sand. In order to improve the adhesion of the core support to moulding sand and core sand, the attachment surface has a pressure-sensitive self-sealing adhesive layer (5). <IMAGE>

Description

SPECIFICATION Core support The invention relates to a core support for foundry practice, with an adhesive surface applicable by means of an adhesive layer to a core consisting of core sand.

Core supports are used in foundry practice in order to support casting cores on mould faces. The insertion of the core support is carried out before assembly of the casting mould, for instance by attaching the core support with its adhesive layer to the core consisting of core sand.

It is known to use, as the adhesive for attaching core supports to cores, an adhesive which also serves to attach together several core parts consisting of core sand. This adhesive is paste-like and can only be applied to the adhesive surface shortly before attaching the core support, since it would otherwise lose the requisite adhesiveness. Application of the adhesive to the adhesive surface of the core support must be carried out carefully, so that the adhesive layer is uniform. Moreover, application of the adhesive must not be excessive, since it would otherwise seep out against the core on insertion of the core support and could lead to failures in the cast workpiece.

Particularly in casting founries in which successive casting moulds are used with if required a large number of core supports, a special person is therefore employed in order to apply the adhesive as required to the adhesive surfaces of the core supports. It has been established, however, that after a realtively short time it is no longer possible for this person to apply the adhesive reliably as a layer of uniform depth. Considerable wastage of the cast workpieces occurs, in consequence.

A further error factor which increases the amount of wastage is that the core support, using this known form of adhesion with a more or less fluid adhesive layer, becomes separated from the core by vibratory stresses, which it is liable to suffer on transport of the assembly of the casting mould to the casting pit.

Apart from the securement of core supports with adhesive layers, it is also known to provide core supports with pins which penetrate into and thus secure the casting mould or the casting core. Such penetration has the disadvantage that the relevant parts consisting of moulding sand may eventually break up, so that the employment of such core supports with securing pins in certain thin-walled mould or core parts is not possible.

In contrast, the invention has the purpose of improving a core support of the kind mentioned initially so that its use is simplified and adhesion of the core support to moulding sand and core sand is improved.

This object is solved in that the adhesive surface is provided with a pressure-sensitive self-sealing adhesive layer.

The expression "a pressure-sensitive selfsealing adhesive layer" is to be understood to mean one which, after removal of any protective sheet provided, for example an oilpaper strip, can adhere to the core by simply pressing the adhesive layer against the core. In contrast, the aforedescribed known adhesive layer is a moisture-sensitive adhesive layer, which, like the adhesive layers of postage stamps, for instance, only becomes a pressure-sensitive adhesive layer after being moistened.

It has been shown that core supports with such adhesive layers, which are sensitizable or develop their adhesive properties merely by the application of pressure, allow rapid application to the moulding sand of the core and a more secure adhesion of core supports to the core, during transport of the casting mould from the place of assembly of the casting mould to the casting pit. The spoilt proportion of cast workpieces produced with these core supports is markedly reduced. Working time, e.g. for core assembly, also is saved, since location of the core supports can be carried out much more rapidly, particularly with prefabrication of the core supports, in which the adhesive surfaces of the core supports are provided with the self-sealing adhesive layer during manufacture.In certain cases of use with a smaller number of core supports, the mould-maker can himself install these core supports, whereas previously with the known core supports a separate person was required.

The invention will be explained in conjunction with an embodiment illustrated in the drawing: The sole figure shows a core support 6, for use particularly in the casting of exhaust pipes, cylinder heads, cylinder blocks, crank housings, gear-boxes etc., and has a core rod 1, on the two ends 2 of which core support plates 3 of circular shape are secured. On the outer or attachment surfaces 4 of the core plates 3, away from the core rod 1, merely pressure-sensitive self-sealing adhesive layers 5 are provided, which are sensitizable by the simple application of pressure, namely when they are pressed against a core. The showing of the self-sealing adhesive layer 5 on the upper attachment surface 4 of the core support 6 is given only partially, for better illustration of the construction of the core support according to the invention.

1. A core support for foundry practice, with an attachment surface applicable by means of an adhesive layer to a core consisting of core and, wherein the attachment surface has a pressure-sensitive self-sealing adhesive layer.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Core support The invention relates to a core support for foundry practice, with an adhesive surface applicable by means of an adhesive layer to a core consisting of core sand. Core supports are used in foundry practice in order to support casting cores on mould faces. The insertion of the core support is carried out before assembly of the casting mould, for instance by attaching the core support with its adhesive layer to the core consisting of core sand. It is known to use, as the adhesive for attaching core supports to cores, an adhesive which also serves to attach together several core parts consisting of core sand. This adhesive is paste-like and can only be applied to the adhesive surface shortly before attaching the core support, since it would otherwise lose the requisite adhesiveness. Application of the adhesive to the adhesive surface of the core support must be carried out carefully, so that the adhesive layer is uniform. Moreover, application of the adhesive must not be excessive, since it would otherwise seep out against the core on insertion of the core support and could lead to failures in the cast workpiece. Particularly in casting founries in which successive casting moulds are used with if required a large number of core supports, a special person is therefore employed in order to apply the adhesive as required to the adhesive surfaces of the core supports. It has been established, however, that after a realtively short time it is no longer possible for this person to apply the adhesive reliably as a layer of uniform depth. Considerable wastage of the cast workpieces occurs, in consequence. A further error factor which increases the amount of wastage is that the core support, using this known form of adhesion with a more or less fluid adhesive layer, becomes separated from the core by vibratory stresses, which it is liable to suffer on transport of the assembly of the casting mould to the casting pit. Apart from the securement of core supports with adhesive layers, it is also known to provide core supports with pins which penetrate into and thus secure the casting mould or the casting core. Such penetration has the disadvantage that the relevant parts consisting of moulding sand may eventually break up, so that the employment of such core supports with securing pins in certain thin-walled mould or core parts is not possible. In contrast, the invention has the purpose of improving a core support of the kind mentioned initially so that its use is simplified and adhesion of the core support to moulding sand and core sand is improved. This object is solved in that the adhesive surface is provided with a pressure-sensitive self-sealing adhesive layer. The expression "a pressure-sensitive selfsealing adhesive layer" is to be understood to mean one which, after removal of any protective sheet provided, for example an oilpaper strip, can adhere to the core by simply pressing the adhesive layer against the core. In contrast, the aforedescribed known adhesive layer is a moisture-sensitive adhesive layer, which, like the adhesive layers of postage stamps, for instance, only becomes a pressure-sensitive adhesive layer after being moistened. It has been shown that core supports with such adhesive layers, which are sensitizable or develop their adhesive properties merely by the application of pressure, allow rapid application to the moulding sand of the core and a more secure adhesion of core supports to the core, during transport of the casting mould from the place of assembly of the casting mould to the casting pit. The spoilt proportion of cast workpieces produced with these core supports is markedly reduced. Working time, e.g. for core assembly, also is saved, since location of the core supports can be carried out much more rapidly, particularly with prefabrication of the core supports, in which the adhesive surfaces of the core supports are provided with the self-sealing adhesive layer during manufacture.In certain cases of use with a smaller number of core supports, the mould-maker can himself install these core supports, whereas previously with the known core supports a separate person was required. The invention will be explained in conjunction with an embodiment illustrated in the drawing: The sole figure shows a core support 6, for use particularly in the casting of exhaust pipes, cylinder heads, cylinder blocks, crank housings, gear-boxes etc., and has a core rod 1, on the two ends 2 of which core support plates 3 of circular shape are secured. On the outer or attachment surfaces 4 of the core plates 3, away from the core rod 1, merely pressure-sensitive self-sealing adhesive layers 5 are provided, which are sensitizable by the simple application of pressure, namely when they are pressed against a core. The showing of the self-sealing adhesive layer 5 on the upper attachment surface 4 of the core support 6 is given only partially, for better illustration of the construction of the core support according to the invention. CLAIMS

1. A core support for foundry practice, with an attachment surface applicable by means of an adhesive layer to a core consisting of core and, wherein the attachment surface has a pressure-sensitive self-sealing adhesive layer.

2. The use of a pressure-sensitive selfsealing adhesive layer on attachment surfaces of core supports in casting practice.

3. A core support according to claim 1, substantially as described with reference to the accompanying drawing.