The present invention relates to a fixture for mounting a pattern plate in a moulding machine of the kind set forth in the preamble of claim 1.
In fixtures of this kind, it is known to use two guide pins positioned in a mutual distance and corresponding bores in order to mount the pattern plate against the mounting surface in a fixed non-rotational manner. In order to be able to accommodate for tolerances in the distance between the guide pins and bores, respectively, due to working tolerances, different thermal expansion coefficients of the different materials of the mounting surface and the pattern plate, etc., it has been used to shape the guide pins and one of the bores cylindrical and the other bore as an elongated bore, whereby the tolerances are accommodated in the elongated bore. A fixture with the features according to the preamble of claim 1 is an internal state of the art. However, this construction has the disadvantage of causing increased wear on the guide pin and the elongated bore when mounting and dismounting the pattern plates on the fixture, due to the mainly linear bearing surface between these elements.
It is the object of the present invention to provide an improved fixture for mounting a pattern plate in a moulding machine of the kind referred to above, with which the above wear problems are reduced substantially, and this object is achieved with a fixture of said kind which, according to the present invention, also comprises the features set forth in the characterising part of claim 1. With this arrangement the tolerances in the distance between the guide pins and bores, respectively, are accommodated by the pivotal movement of the pivotally mounted fitting on which one guide pin is mounted, in the following called "the swingable guide pin". By the features set forth in claim 2 it is achieved that the movements of the swingable guide pin is mainly in the direction of the connection line between the two guide pins, the movement in the perpendicular direction only being of second order compared to this. Preferred embodiments of the invention are revealed in the further subordinate claims.
In the following detailed part of the present description, the invention will be explained in more detail with reference to the exemplary embodiments of a fixture for mounting a pattern plate in a moulding machine according to the invention shown in the drawings in which:
The fixture for mounting a pattern plate 1, as shown in Figures 1 and 2, is intended to be used for providing a fixed, non-rotational mounting of the pattern plate 1 with its mainly planar surface 2 against a corresponding mounting surface 3 in the moulding machine. The pattern plate 1 comprises a pattern side (not shown) opposite the mainly planar surface 2. In order to provide the fixed, non-rotational mounting of the pattern plate two guide pins 4 and 5 are mounted in the mounting surface 3 and corresponding bores (one not shown) and 7 are positioned in the mainly planar surface 2 of the pattern plate 1 for engagement with the two guide pins 4 and 5. In the construction shown in Fig. 1 the guide pin 4 is fixed, and in order to accommodate tolerances in the distance a between the guide pins 4, 5 and the bores (one not shown) 7, one guide pin 5 is mounted on a pivotally mounted fitting 8 having a pivot axis 9 positioned at a distance b from the connection line 10 between the two guide pins 4 and 5. In this way the guide pin 5 is swingably mounted in such a way that the movement of the guide pin 5 is mainly in the direction of the connecting line 10 between the two guide pins 4 and 5. As shown in Fig. 2, the pivotally mounted fitting 8 is positioned in a recess 12 provided in the mounting surface 3. Alternatively, the pivotally mounted fitting 8 could be positioned in a corresponding recess provided in the planar surface 2 of the pattern plate 1, although this would require a larger dimension of the pattern plate and thereby a reduction of the possible dimension of the pattern in this direction. In order to minimise the movement of the guide pin 5 in the direction perpendicular to the connection line 10 between the two guide pins 4, 5, the pivot axis 9 is positioned in such a way that in the neutral position shown in Fig. 1 the connection line 11 between the pivot axis 9 and the swingably mounted guide pin 5 forms a substantially right angle with the line 10 connecting the guide pins 4 and 5
The above construction has been described in connection with an embodiment in which the guide pins 4, 5 are positioned in the mounting surface 3, and the bores 7 are positioned in the surface 2 of the pattern plate 1, but it will naturally also be possible to position these elements in the opposite surfaces.
In order to facilitate the mounting of the pattern plate 1 with its bores 7 in engagement with the guide pins 4, 5, it may be advantageous to have the swingably mounted guide pin 5 extending further out from the planar surface 3 than the fixed guide pin 4, whereby the bore 7 of the pattern plate 1 can be brought into engagement with the guide pin 5 before the other bore is brought into engagement with the guide pin 4, providing a possibility of moving the pattern plate 1 in a direction along the line 10 connecting the two guide pins 4, 5, in order to bring the other bore into engagement with the fixed guide pin 4.
To be used as an alternative to or in combination with the above measures for engaging the guide pins 4, 5 in the corresponding bores 7, the guide pins 4, 5 and/or the bores 7 can be provided with a conical inlet formation, and the swingably mounted guide pin 5 may be elastically prestressed towards the neutral position, e.g. by means of a rubber bushing or a spring.
In the construction shown in Fig. 3, the "fixed" guide pin 4 is provided with an adjustment possibility in the direction of the connection line 10 between the two guide pins 4 and 5. By the swingable mounting of the guide pin 5 it is thus possible to adjust the position of the pattern plate 1 in the direction of the connection line between the two guide pins 4 and 5 by a simple adjustment of the position of the "fixed" guide pin 4. This provides a possibility of compensating for misalignment of the pattern plate in this direction.
The fixture for mounting the pattern plate 1 in a moulding machine has been developed for use in connection with a moulding machine producing sand moulds for a mould-string-casting plant comprising a swingable squeeze plate for mounting a first pattern plate 1 and an oppositely positioned squeeze plate for mounting a second pattern plate 1, said pattern plates forming two sides of a squeeze chamber for forming sand moulds or the like. Although this has been the aim of the development of the invention, it will be clear for a man skilled in the art that the construction can be used in connection with many other types of moulding machines producing sand moulds.