EP0630304B1 - Device for shooting foundry cores or moulds with moulding materials - Google Patents

Abstract

A device for shooting foundry cores or moulds with moulding materials (1) has a shooting head (4) with an inlet side (2) and an outlet side (3), a shooting plate (6) located at the outlet side of the shooting head (4) and bearing at least one shooting nozzle (5) and a clamping head (7) located at the inlet side of the shooting head (4) and having at least an air supply (8) for sealing the shooting head (4) by applying compressed air thereon. The clamping head (7) is preferably movable vertically by means of a cylinder-piston arrangement (9). In order to avoid local air currents or to make the air flow more uniform during core shooting, said device is designed in such a way that a device (10) for swirling or uniformly distributing the compressed air that flows from the air supply (8) into the shooting head (4) is arranged between the shooting head (4) and the clamping head (7).

Description

The invention relates to a device for firing foundry cores or molds with molding materials, having a weft head having an inlet side and an outlet side, a weft plate associated with the weft head on the outlet side and carrying at least one weft nozzle, and a tensioning head for the sealing side which is assigned to the weft head and has at least one air supply Compression of compressed air to the shot head, the clamping head being vertically movable by means of a cylinder-piston arrangement and a filter being provided in the flow path of the compressed air.

Core shooters have been known in foundry technology for many years. For the casting of molded pieces, the foundry cores or molds are usually manufactured in separate parts, brought together and connected to one another to form a casting mold. An essential part of the core shooters are the so-called shot heads with the shot plates carrying the shot nozzles. Molding material, in particular core sand, i.e. Quartz sand already mixed or coated with binder has so far been filled into the shot heads in question and from there it is blown or shot into the respective molds with very high air pressure through the nozzles arranged in the shot plate.

A firing device for foundry cores is known from GB-A-2 194 745, a predeterminable air pressure being generated there at a certain point in time with a practically constant amount of air for the sudden compressed air supply to the firing head designed as a sand cartridge. Avoiding a Pressure drop during the shooting process is assumed here.

According to Fig. 1 of GB-A-2 194 745 and from the associated description it is further known that a filter is provided at the outlet end of the chuck. In addition to its usual purpose, this filter serves exclusively to prevent backflow of the core sands whirled up in the shot head.

Specifically, compressed air should be able to get there both from the clamping head into the shooting head and back from the shooting head into the clamping head. The need for the filter disclosed in GB-A-2 194 745 to avoid the flow of entrained core sand back into the chuck is evident in that a radial outlet port is provided in the lower chamber of the hold-down for airtight connection of a conventional quick exhaust valve. If this quick exhaust valve is actuated before the clamping head is lifted, Kersand gets into the clamping head without the provision of the filter and causes considerable wear or even damage to the valves there.

However, the device for firing foundry cores or molds known from GB-A-2 194 745 is problematic insofar as the compressed air passes through the filter but otherwise directly into the interior of the shot head, the compressed air being the sand in the shot head swirls so that local swirls occur within the shot head or within the cartridge. The compressed air impacts directly on the core sand in the shot head, so that pre-compression already takes place there. Due to the uncontrolled supply of compressed air, no targeted, homogeneous pressurized air can be applied to the sand within the shot head. The at In the known device, locally occurring "compressed air jets" virtually drill holes in the sand in the shot head or even cause the previously mentioned local pre-compression of the sand, which is usually already provided or coated with binder. Consequently, the pressure required for shooting must be increased significantly due to this unequal compressed air radiation and pre-compression. Consequently, there is a very particular risk here that the molding sand is - unintentionally - pre-compressed in the shot head, so that considerably higher pressures are required for the actual shooting.

From "Patent Abstract of Japan", vol. 4 no. 143 (M-35) (625) is known per se a shot head which has a shot plate carrying shot nozzles in the usual way. Special filters are not provided here.

The invention is therefore based on the object of specifying a device for shooting foundry cores or molds with molding materials, in which the molding materials located in the shot head are at least largely uniformly acted upon by compressed air.

The device according to the invention solves the above object by the features of claim 1. Thereafter, the above-mentioned device is designed in such a way that the filter is arranged between the shot head and the tensioning head and is used to swirl or evenly distribute the compressed air flowing from the air supply into the shot head as Gap filter is designed with preferably parallel columns.

According to the invention, it has accordingly been recognized that compressed air flowing directly into the shot head to desired local ones "Burial" or even local densification. Consequently, a device is provided in the manner according to the invention which distributes the inflowing compressed air - effectively or evenly - already in the shot head - towards the molding material. This device is further provided according to the invention between the shot head and the tensioning head, so that the device in question has a double function, namely on the one hand the swirling or uniform distribution of the air flowing from the air supply into the shot head and on the other hand one from a standing position filter function known in the art for air possibly flowing back from the shot head into the clamping head or from there through the air supply into a compressor or into a pump or the like. Consequently, in the manner according to the invention, on the one hand, the shooting process is favored to the extent that, because of the uniform distribution of the compressed air within the shooting head, lower pressures are required for shooting. On the other hand, an undesirable backflow of particles, floating particles or the like. And thus an abrasive wear of the components upstream of the shot head is effectively prevented, if not avoided, whereby it is very important that the device in question is provided between the shot head and the clamping head .

A gap filter can be understood here to mean, for example, a finely slotted plate, the slots or gaps extending from one edge region of the filter to the other - quasi diagonally. The gaps in question can be spaced from one another in a further advantageous manner by 10 to 15 mm. The distance between the columns is preferably approximately 12 mm. So that these gaps actually cause an air build-up on the upstream side and thus a higher pressure than on the downstream side, the gaps are equipped with a width of approx. 3/100 to 6/100 mm. The gap width can also vary readily, with a wider configuration of the Gap width leads to a pressure drop on the upstream side, which has a disadvantageous effect on an even distribution of compressed air within the shot head. If the gaps are much narrower, the air pressure on the inflow side must be increased so that the air pressure building up after the filter is sufficient for core shooting. In addition, care must be taken that the gap width is selected in dependence on the molding material used so that the gaps are not blocked by the molding material or molding sand when the compressed air flows backwards.

The gaps or the webs separating the gaps can be arranged in such a way that the gaps guide the compressed air essentially longitudinally into the shooting head. Likewise, the filter could be provided with uniformly or differently inclined gaps to generate a specific flow pattern in order to achieve a specific scattering of the compressed air. The inflow angles to be provided here could each be matched to the corresponding shooting head. Furthermore, this measure makes it possible to make the filter smaller in diameter than the opening of the shot head, whereby a certain inclination of the gaps can nevertheless be used to apply compressed air to the entire interior of the shot head.

In a further advantageous embodiment, the filter can have a thickness which corresponds to the spacing of the gaps, ie the thickness of the webs between the gaps. This would result in a thickness of 10 to 15 mm, in particular a thickness of 12 mm. This would ensure that the filter has sufficient stability in the compressed air path with appropriate materials. A stainless steel, preferably stainless steel, could be used as the material. The use of stainless steel is particularly advantageous due to the aggressiveness of the binders.

To securely fix or clamp the filter between the clamping head and the shooting head, it is particularly advantageous if the filter is held by a ring which is essentially matched to the shooting head or the clamping head. This ring serving as a holder could either be releasably connected to the shooting head or to the clamping head. A detachable connection of the ring and thus of the filter to the clamping head is advantageous, however, insofar as the filter would be removable together with the clamping head for refilling the shot head with core sand. An additional step to remove the filter would thus be omitted in a particularly advantageous manner.

The ring used to hold the filter could be designed in such a way that the filter would be inserted into an inner edge recess of the ring or would rest on the bottom of the edge recess. This would completely sink the filter in the ring and damage to the filter due to improper handling would be largely avoided, at least in the edge area.

To further secure and support the filter, the ring could have a support rib running approximately diagonally in the middle. This support rib would advantageously lie in one plane with the bottom of the edge recess, so that the filter inserted into the edge recess rests on the support rib and on the bottom of the edge recess.

The clamping head could also have an approximately centrally formed rib or at least a corresponding eye on its side facing the shooting head, so that the filter would be fixed in the installed state between the supporting rib of the ring and the rib of the clamping head. In this respect, the filter would be both with incoming compressed air and with returning compressed air and possibly backflow particles adequately secured against deformation or displacement.

So that the ring located between the clamping head and the shooting head does not cause any pressure loss, the ring has seals both on the side facing the clamping head and on the side facing the shooting head, which seal on the one hand between the ring and clamping head, and on the other hand between the ring and the shooting head. These seals can be, for example, conventional sealing rings or O-rings, which squeeze onto the shooting head when the clamping head is pressed on and thus seal effectively.

With regard to a uniform distribution of compressed air within the shot head, it is a further advantage if at least two separate air feeds are provided, which enter the shot head at different points via the tensioning head. The air supply lines on the outer edge region of the clamping head are advantageously connected to the latter. The air supply lines are designed in the form of tubes which run essentially along the clamping head or along the vertical direction of movement of the clamping head. The air inlets or pipes are firmly connected to the clamping head and form an additional guide for the clamping head in its vertical movement. For this purpose, the tubes themselves are guided in a manner known per se or are appropriately stored.

The compressed air flowing through the pipes first into the clamping head and from there into the shooting head is deflected transversely to the clamping head in its region facing the shooting head via connecting pieces adjoining the air supply lines or pipes. This area is open to the shooting head, so that the compressed air that has entered this area can reach the shooting head unhindered - through the filter. The connectors deflect the compressed air flowing from the air inlets by approximately 90 °, ie the air flows into the clamping head transversely to the vertical direction of movement thereof.

Furthermore, it is essential that, in the context of a particularly advantageous embodiment, the area of the clamping head facing the shooting head is surrounded by an edge area projecting towards the shooting head. The connectors are parts or integral parts of the edge area. In other words, the clamping head with its edge area forms a kind of hood, to which the ring with the filter located there connects.

Finally, it is of particular advantage if the areas of the connecting pieces which are exposed to increased abrasive wear, i.e. the areas directly flown by the compressed air are designed as replaceable wear parts. These are, in particular, those areas of the connecting pieces which, seen in the direction of flow, form outer curve walls which are always flowed directly by the flow medium.

Fig. 1

in einer schematischen Seitenansicht, geschnitten, ein Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung zum Schießen von Gießereikernen oder -formen mit Formstoffen, wobei sich die Vorrichtung in ihrer Arbeitsposition befindet,

Fig. 2

in einer Draufsicht, schematisch, das in einen Ring eingelegte bzw. dort festgelegte Filter aus Fig. 1 und

Fig. 3

in einer vergrößerten Seitenansicht, teilweise und geschnitten, das Filter aus Fig. 2.

There are now various possibilities for advantageously designing and developing the teaching of the present invention. For this purpose, on the one hand, reference is made to the claims subordinate to claim 1, and on the other hand to the following explanation of an embodiment of the invention with reference to the drawing. In connection with the explanation of the preferred exemplary embodiment of the invention with reference to the drawing, generally preferred configurations and developments of the teaching are also explained. In the drawing shows

Fig. 1

in a schematic side view, sectioned, an embodiment of a device according to the invention for shooting foundry cores or molds with molding materials, the device being in its working position,

Fig. 2

in a plan view, schematically, the filter inserted in a ring or fixed there from Fig. 1 and

Fig. 3

in an enlarged side view, partially and in section, the filter from FIG. 2.

1 shows an embodiment of a device according to the invention for shooting foundry cores or molds with molding materials or molding sand 1. The device according to the invention has a shooting head 4 having an inlet side 2 and an outlet side 3. On the outlet side, the shot head 4 is assigned a shot plate 6 carrying shot nozzles 5. On the inlet side, the clamping head 4 is assigned a clamping head 7, which in turn has an air supply 8. The clamping head serves among other things for the pressurized compressed air supply to the shooting head 4, the clamping head 7 being vertically movable by means of a cylinder-piston arrangement 9.

According to the invention, a device 10 for swirling or evenly distributing the compressed air flowing from the air supply 8 into the shot head 4 is provided between the shot head 4 and the tensioning head 7. The device 10 for swirling or evenly distributing the compressed air is designed according to the invention as a filter 11, more precisely as a gap filter.

2 and 3 show particularly clearly that the filter 11 designed as a gap filter has gaps 12 running parallel to one another. These gaps 12 are spaced 12 mm apart. The columns 12 themselves have a width of approximately 3/100 to 6/100 mm. The columns 12 run essentially parallel to one another and diverge on the upstream side in such a way that the webs 13 located between the columns 12 taper on the upstream side (cf. FIG. 3).

2 and 3 also show together that the column 12 feed the compressed air into the shot head 4 essentially in the longitudinal direction. Any other angle - different from gap to gap - would be conceivable. The filter 11 itself has a thickness of approximately 12 mm and is made of stainless steel.

1 and 2 show together that the filter 11 is held by a ring 14 which is essentially adapted to the clamping head 7 and that the ring 14 is detachably connected to the clamping head 7. The filter 11 has an inner edge recess 15, in which the filter 11 is fixed on top.

The ring 14 furthermore has a support rib 16 which runs approximately diagonally in the middle and which can be seen in cross section in the illustration according to FIG. 1. The support rib 16 lies with the bottom of the edge recess 15 in one plane, so that the filter 11 inserted into the edge recess 15 rests on the support rib 16 and on the bottom of the edge recess 15.

Furthermore, the clamping head 7 on its side facing the shooting head 4 has an approximately centrally formed rib or a corresponding eye 17, so that the filter 11 is fixed between the supporting rib 16 of the ring 14 and the rib or the eye 17 of the clamping head 7 is.

Fig. 1 further shows that the ring 14 has seals 18 both on the side facing the clamping head 7 and on the side facing the shooting head 4, the one hand between seal the ring 14 and the clamping head 7, on the other hand between the ring 14 and the shooting head 4.

For a more uniform air supply, two separate air supply lines 8 are provided, which are connected to the clamping head 7 on the outer edge region thereof. The air inlets 8 are designed in the form of tubes and run essentially along the clamping head 7. They are firmly connected to the clamping head 7 and additionally guide it in its vertical movement.

The compressed air is deflected transversely to the clamping head 7 in its area facing the shooting head 4 via connecting pieces 19 adjoining the air supply lines 8. The connecting pieces 19 deflect the compressed air flowing in from the air supply lines 8 by about 90 °.

The area of the clamping head 7 facing the shooting head 4 is surrounded by an edge area 20 projecting towards the shooting head 4. The connecting pieces 19 are parts of the edge area 20. The areas of the connecting pieces 19 exposed to increased abrasive wear, i.e. the areas directly flowed by the compressed air, designed as replaceable wear parts 21.

Claims (10)

1. Device for shooting foundry cores or moulds with moulding materials (1), comprising a shooting head (4) with an inlet side (2) and an outlet side (3), a shooting plate (6) associated with the outlet side of the shooting head (4) and accommodating at least one shooting nozzle (5), and a clamping head (7) associated with the shooting head (4) on the inlet side of said shooting head and comprising at least one air supply (8) for a sealing application of compressed air to the shooting head (4), the clamping head preferably being vertically movable by means of a cylinder-piston arrangement (9), and a filter (11) being provided in the flow path of the compressed air, characterised in that the filter (11) is arranged between the shooting head (4) and the clamping head (7) and, in order to swirl or uniformly distribute the compressed air flowing from the air supply (8) into the shooting head (4), is constructed as a streamline filter with slits (12) preferably extending parallel to one another.
2. Device according to Claim 1, characterised in that the slits (12) are spaced 10 to 15 mm, and preferably 12 mm, apart from one another and in that the filter (11) is preferably 12 mm thick.
3. Device according to either one of Claims 1 and 2, characterised in that the width of the slits (12) is from 3/100 to 6/100 mm.
4. Device according to any one of Claims 1 to 3, characterised in that the slits (12) extend substantially parallel to one another and diverge on the inflow side, such that the webs (13) which are located between the gaps (12) taper on the inflow side, wherein the slits (12) conduct the compressed air into the shooting head (4) substantially in the longitudinal direction or at a common angle or at several different angles.
5. Device according to any one of Claims 1 to 4, characterised in that the filter (11) is made of stainless steel, preferably of special steel.
6. Device according to any one of Claims 2 to 5, characterised in that the filter (11) is retained by a ring (14) which is substantially adapted to the shooting head (4) or the clamping head (7); in that the ring (14) is releasably connected to either the shooting head (4) or the clamping head (7); and in that the filter (11) is optionally inserted in an inner edge cutout (15) of the ring (14) or secured bearing on the base of the edge cutout (15).
7. Device according to any one of Claims 1 to 6, characterised in that the ring (14) comprises a support rib (16) extending diagonally approximately in the centre thereof; in that the support rib (16) extends in one plane with the base of the edge cutout (15); and in that the filter inserted into the edge cutout (15) bears on the support rib (16) and on the base of the edge cutout (15).
8. Device according to any one of Claims 1 to 7, characterised in that the clamping head (7) is provided, on the side thereof which faces the shooting head (4), with a rib or a corresponding eye (17) formed approximately in the centre of said clamping head; in that the filter (11) is secured between the support rib (16) of the ring (14) and the rib (17) of the clamping head (7); and in that the ring (14) comprises seals (18) both on the side which faces the clamping head (7) and on the side which faces the shooting head (4), which seals seal between the ring (14) and the clamping head (7) on the one hand and between the ring (14) and the shooting head (4) on the other hand.
9. Device according to any one of Claims 1 to 8, characterised in that at least two separate air supplies (8), which are separated from one another, are provided; in that the air supplies (8) are formed on the outer edge area (20) of the clamping head (7) and connected thereto, and are optionally formed as pipes, extend substantially along the clamping head (7), are connected securely to the clamping head (7) and additionally guide this in its vertical movement, wherein the compressed air being deflected, optionally via connection pieces (19) which are connected to the air guides (8), transversely to the clamping head (7), into the area thereof which faces the shooting head (4), and wherein the connection pieces (19) preferably deflect the compressed air flowing from the air supplies (8) by approximately 90°.
10. Device according to Claim 9, characterised in that the area of the clamping head (7) which faces the shooting head (4) is surrounded by an edge area (20) which projects downwards towards the shooting head (4); in that the connection pieces (19) are parts or integral components of the edge area (20); and in that, preferably, the areas of the connection pieces (19) which are subject to an increased abrasive wearing, ie. which are flowed towards directly by the compressed air, are produced as exchangeable expendable parts (21).

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