The present invention relates to a riser comprising a riser body with a movable spout, the riser body having a riser opening for the liquid metal passing therethrough and the spout being provided in the riser opening. The spout tapers at the end facing away from the riser body and has at least one circumferential bead in the tapered portion and optionally a circumferential lip at the end of the tapered portion, i.e. , in the outlet, the circumferential lip being turned inwards. In addition, the present invention relates to an assembly comprising the riser, a pattern plate and a centring pin which is passed through the spout, and to the use of the riser or assembly for metal casting.

State of the art

Risers, also called feeders, are used in the casting of metals in casting moulds. The risers usually have a riser cavity configured to receive the molten metal. The mould material that is used to make the casting mould and will form the casting mould surrounds the riser. The casting space inside the casting mould that is provided for receiving the liquid metal has a passage to the riser cavity, into which a partial quantity of the liquid metal filled into the casting mould then enters during the casting process. The molten metal that then rises into the riser builds up a metallostatic pressure and, since the casting is subject to shrinkage while it solidifies, is intended to flow back into the casting mould while the casting solidifies, in order to compensate for the loss of volume caused by the shrinkage of the casting during solidification. The casting mould is produced by means of a pattern comprising pattern plates by moulding the moulding material mixture using the pattern and curing the moulding material mixture to obtain the moulding material.

In order to ensure that the metal in the riser flows back, it must be ensured that the metal in the riser is still liquid, while the metal inside the casting mould has already at least partially solidified to form the casting. For this purpose, at least part of the riser, typically the riser body, is usually made of an insulating and/or exothermic material. The exothermic material ignites when liquid metal enters the riser, due to the higher temperature then prevailing. This is the moment when an exothermic reaction takes place automatically within the material of the riser, this reaction causing thermal energy to be supplied to the metal in the riser over a certain period and the metal in the riser cavity and in the transition area to the casting cavity of the casting mould to be kept in a liquid state. If the riser body is exothermic, a lid, if any, does not necessarily have to be exothermic as well and can, for example, also be insulating (or neither).

An insulating riser is designed in such a way that the liquid metal in the riser cavity cools more slowly than in the casting cavity because the riser material in the riser provides better insulation. Typically, the riser body is insulating, although a lid, if any, does not necessarily have to be insulating as well. The surrounding cured moulding material also has an insulating effect.

Risers are often used in conjunction with a breaker core (also called a constrictor core). A breaker core is an intermediate piece with a passage that connects the mould cavity and the riser cavity, such as a spout. Therein, the diameter of the passage is dimensioned such that it decreases in size from the riser cavity to the mould cavity, so that knocking off takes place at the breaker core near the surface of the casting (the constriction). Breaker cores may consist of the riser material of the riser body, but may also be made of metal, plastic or cardboard.

Risers can be mounted on horizontal pattern plates or vertical pattern plates. In case of the latter the risers are also called side risers. A side riser is known from DE 3423220 A1 , which comprises a riser base to be attached laterally to a mould model having the riser opening for the liquid metal and a riser part placed thereon. The riser part placed on top of the riser base forms the riser cavity, the majority of the volume of which is arranged above the horizontally running riser axis or spout axis through the riser opening in the riser base.

In order to form a breaking edge, risers with a tubular body as a spout have already been proposed in EP 1345716 B1 , wherein the spout tapers towards the end facing the casting. EP1850987 B1 discloses a riser with a movable spout which can be easily packed and transported because the spout can be moved into the riser cavity for transport.

Risers are often mounted on centring pins which can also be designed as a spring mandrel, also known as spring pin. If rigid, the centring pin pushes through the lid of the riser body during compression of the moulding material mixture. The spring mandrel accommodates the movement by shortening its length via a spring mechanism. The centring pin is mounted on the pattern or pattern plate.

Object of the invention

It is an object of the present invention to provide improved risers with a movable spout. The spout should stand firmly on the pattern plate of the pattern or on a, possibly bevelled, base of the centring pin and should remain in this position during compaction of the moulding material mixture. The centring pin is mounted on the pattern plate and is removed along with the pattern plate. The spout should be able to withstand forces on the riser during compaction of the moulding material mixture, especially if the forces act asymmetrically. Angular forces can act on the riser during compaction of the moulding material mixture, bending the spout at the bottom of the breaker core around the centring pin and resulting in a poor breaking edge. In addition, the spout should not fall back into the cavity of the riser body or move away from the pattern plate (or away from the base of the centring pin). As a result, a clean breaking edge should form near the surface of the casting during stripping. Often, this cannot be ensured if the spout is bent by angular forces, especially in the first end region.

Summary of the invention

This object is achieved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the subordinate claims or are discussed below. The riser comprises at least: a riser body with a cavity and a spout for connecting a casting mould to the cavity of the riser body via a riser opening, wherein the spout is formed by a tubular body and the tubular body has a first end region with an outlet and a second end region opposite the first end region, the first end region connecting to the mould via the outlet and the second end region connecting to the cavity of the riser body, wherein the first end region has a tapered region and the tapered region tapers towards the outlet, wherein the spout is movably arranged in the riser opening of the riser body and can be pushed at least partially into the riser body with its second end region, and wherein the tapered region has zones comprising at least a first groove zone with a groove and adjacent thereto at least one bead zone with a bead, so that in the tapered region there results a succession of surfaces orthogonal to the spout axis in the direction from the cavity of the riser body towards the outlet, wherein the surfaces in the first groove zone decrease in size and the surfaces in the transition area from the first groove zone to the bead zone increase in size to form an outwardly bulging bead and decrease in size again when the bead subsides, and

The tapered region may have optionally an inwardly formed circumferential lip at the outlet. The inwardly formed circumferential lip may be substantially perpendicular to the spout axis.

According to an optional embodiment of the invention the tapered region has a second groove (19) in the direction from the riser cavity towards the outlet following the bead, and preferably the first groove has the deeper constriction of the tapered region relative to the second groove.

According to an optional embodiment of the invention the spout has an outwardly projecting stop at the second end region, more particularly at the end of the second end region, and the stop is in particular an outwardly bent brim. According to an optional of the invention the spout is rotationally symmetrical along the spout axis.

According to an optional of the invention the bead has a (mean) bead height and the bead height is shorter than the (mean) length of the first constriction of the (first) groove, more particularly shorter by more than 10%, and/or the (mean) length of the second constriction, if present, is shorter than the (mean) length of the first constriction of the first groove, more particularly shorter by more than 30%.

According to a further optional embodiment of the invention the first volume (20) under the enveloping surface of the first groove is larger than the second volume under the second groove, more particularly more than 50% larger.

According to a further optional embodiment of the invention the first groove and the bead and, if present, also the second groove are obtainable by knurling.

According to a further optional embodiment of the invention the first groove and the bead and, if present, also the second groove merge into each other by means of curves and not by angular edges.

The invention is also directed to an assembly or assembly arrangement comprising the above riser and further comprising a pattern plate and a pin. The pin end is arranged on the pattern plate, wherein the spout is guided by the pin and the pin extends through the riser opening into the cavity of the riser. The pin end rests on an inner wall of the riser body or a lid opposite the riser opening and the outlet of the spout rests on the base of the pin or on the pattern plate.

The invention is also directed to the use of the riser as above defined in the above assembly arrangement in metal casting for feeding liquid metal. The tapered region may have a second groove zone following the bead in the direction from the riser cavity towards the outlet (or the second end region to the first end region), so that the surfaces continue to decrease in size as they come from the bead and then increase in size as the surfaces leave the second groove zone with a second groove.

The surfaces at the beginning of the first groove zone are larger than at the end of the second groove zone; or, if there is no second groove zone, the surfaces at the beginning of the first groove zone are larger than at the end of the bead zone.

Preferably, the surfaces at the point of the deepest constriction of the first groove zone are larger than at the point of the deepest constriction of the second groove zone.

Preferably, the surfaces at the point of the deepest constriction of the first groove zone are larger than at the end of the bead zone (if there is no second groove zone).

Preferably, the groove zone(s) and the bead zone do not have any angular or angled edges (where two surfaces meet at an angle along an edge) but only round transitions.

Therein, the stability of the spout is such that the round transitions (or less preferably the edges) do not deform during compaction and the spout reacts to the compaction pressure only by moving into the riser cavity, with the riser body sliding over the spout towards the pattern plate.

Furthermore, an enveloping surface tangentially applied to the highest point of the bead on one side and to the nearest highest point in the direction of the second end portion encloses a larger volume (first volume) than the second volume under the enveloping surface of an enveloping surface tangentially applied to the highest point of the bead on one side and to the nearest highest point in the direction of the first end portion. The first volume virtually functions as a storage volume that holds down the spout when the moulding material mixture is being compacted. The compaction forces on the spout thus act in the direction of the pattern plate or the mould cavity during compaction. In particular, the first volume is 30%, preferably 50%, larger than the second volume.

In particular, the tapered region has one bead and one groove next to the bead or has one bead and two grooves on either side of the one bead.

The tapered region and more particularly the entire spout as well do not deform during compaction of the moulding material. The spout material is formed with the appropriate stiffness. A further reason that the spout does not deform is the fact that the spout is moveable.

According to one embodiment, the first end region of the spout at the outlet has an inwardly formed circumferential lip. The inwardly formed circumferential lip improves the formation of a breaking edge and strengthens the spout, both with regard to the contact surface and against deformation of the spout when angular forces occur, i.e., forces perpendicular to the spout axis. To form the circumferential lip, the spout bends inwards at the outlet, more particularly approximately perpendicular to the spout axis. The width of the lip, for example, corresponds to about 1 % to 20% of the diameter of the outlet. Irrespective, the width of the lip is 0.3 to 5 mm, more particularly 0.5 and 3 mm.

According to one embodiment the spout is rotationally symmetrical, especially along the spout axis. However, the spout can also be oval, more particularly oval in the first end region and round in the second end region. An oval spout can rest better on a thin rim of the mould pattern.

The riser according to the invention comprises at least one riser body and a spout, wherein the riser body has a riser opening for the liquid metal and the spout is movably mounted in the riser opening, more particularly also under its own weight. The riser body can be made of several parts and may, for example, include a lid. The lid does not have to be made of the same material as the rest of the riser body. The riser is intended to be used when metals are cast in horizontally and vertically separable casting moulds. The riser is mounted on the pattern plate using a pin (centring pin) which is guided through the spout and the riser opening and extends, e.g., to the lid or the upper side of the riser cavity. There, a recess can be provided for fixing the tip of the pin.

Detailed description of the invention

The spout serves as an extension of the riser opening for attaching to a pattern plate, which may also be a swivelling mould pattern.

The molten metal enters the cavity via the spout and the riser opening when the liquid metal is poured into the casting mould. During the casting process, the riser cavity is configured to receive the liquid metal and dispense it at a later point via the riser opening. While the casting is shrinking, the molten metal then flows back from the riser cavity and through the riser opening of the riser body via the nozzle and into the casting until the casting has completely solidified.

The spout is moulded from metal. The spout can dissolve when the hot metal penetrates it, with the surrounding mould material then forming the bond to the casting.

The spout rests on the pattern plate or on a base of the centring pin, wherein the base can be bevelled. In this configuration, the spout, while resting on the bevelled base of the centring pin, is slightly spaced apart from the pattern plate. The spout remains in this position even during compaction of the moulding material mixture, thus ensuring that a defined breaking edge is provided directly at the casting. The spout acts as a metal breaker core that can be compressed by pushing it into the riser cavity, the metal breaker core ensuring minimum riser residues after knocking off of the riser. Grinding and smoothing is minimised and can often even be eliminated. The riser body moves towards the model relative to the spout when the moulding material is compacted. Herein, the spout with parts of the second end region slides into the riser opening and into the riser cavity.

At the same time, the moulding material mixture, while compacting, presses the spout firmly with the contact surface against the pattern plate or the base of the centring pin, because the moulding material mixture, while compacting, can grip the bead during the compacting movement and gets caught in the first volume. Towards the casting or mould cavity, the spout should rest on the pattern plate or the base of the centring pin. As a result, a connection is formed between the mould cavity and the spout. The bead with the groove causes the spout to be pressed towards its contact surface when the moulding material mixture is compacted.

At the same time, the bead and the groove have the effect of stiffening the spout so that the spout deforms less easily when subjected to angular forces, especially in the vicinity of the outlet, where deformation would interfere with the formation of a clean breaking edge. Likewise, the optional circumferential lip results in stiffening.

The spout can be pre-assembled and then transported in a space-saving and safe way. The riser can be turned upside down and the spout (at least in sections) is stored inside the riser body, i.e. , the riser cavity, to save space. According to a preferred embodiment, when the riser is turned back into its position of use, with the spout facing the pattern plate or the casting mould, the spout slips out of the interior of the riser body due to its own weight until the spout touches down on the upper stop. In this assembly position, the riser can be placed on top of the pin and the spout can already slide into the cavity of the riser body to a certain degree. If the appropriate mould pressure is now applied after the moulding material mixture has been filled in, the spout can be pushed back into the riser cavity by a certain amount of the distance it has moved out, so that the riser body can move towards the pattern plate in response to the reduction in volume caused by the compaction of the moulding material. For the purposes of the present invention, a spout is understood to particularly mean a tube-like body as described in DE 102005008324 A1 . In addition to the tubular spout, i.e. , one that has a round cross-section, an oval cross-section is also possible, e.g., obtained by compressing the tubular spout.

The spout tapers towards its first end region, the tapered portion. The second end region forms a shaft that can move into the riser cavity. If desired, a shaft bead may be provided where the tapered portion turns into the shaft or in the shaft portion only, the shaft bead acting as a stop when the spout is moved into the riser cavity of the riser body and through the riser opening with its shaft portion.

The spout can have different lengths. Usual lengths are approximately between 15 mm and 300 mm, more particularly between 35 mm and 100 mm. The length of the spout is selected such that at least the distance between the riser prior to moulding and the mould pattern or the casting mould is bridged. The inner diameter of the spout, more particularly the inner diameter of the outlet, can generally be selected as desired; however, the opening should be large enough to ensure that - depending on the required volume and necessary time interval - the molten metal can flow into or out of the riser during the casting and solidification process. The diameter of the spout is based on the diameter of the riser opening for the spout, since according to one embodiment of the present invention the spout is inserted into the riser body.

Depending on the material used, the wall thickness of the spout will typically be between 0.05 mm and 5 mm, more particularly between 0.15 mm and 0.5 mm.

The length of the spout and the height of the cavity of the riser body are preferably dimensioned such that, in the inserted position in which the risers are usually transported, the spout is so completely inserted into the riser cavity of the riser body that the spout no longer extends out of the riser opening - except for the wall thickness of the riser opening where appropriate.

In particular, the spout is made of metal and more particularly of a metal similar to the casting programme, such as aluminium-, iron- or steel sheet. In one embodiment, the spout has a stop at its end facing the riser cavity. The stop is arranged at such a position on the spout that it is still inside the riser cavity when the spout is pulled out to its maximum. When pulling the spout out of the riser body, the stop comes to rest, e.g., on the bottom of the riser cavity, in that area of the bottom that adjoins the riser opening.

In general, the stop can be of any design as long as it is ensured that the spout cannot fall out of the riser opening. The stop can, for example, be formed as a thickening on the outside of the spout and run around the spout along its circumference in the form of a bead. Individual projections are also possible as a stop. Usually, the stop is made of the same material as the spout. However, it is also possible that the stop is formed from a different material. Preferably, both the spout (at least in its second end region) and the stop are circular, wherein the stop then runs around the spout at the upper end like a hat brim.

The spout can be made, for example, by deep drawing and knurling. In case of deep drawing, the sheet metal is formed into a seamless shape in one or more passes. The starting material, regardless of whether it is a round plate or a blank, is inserted between the upper and lower dies and pressed into a cup shape during the downward movement of the drawing punch. The bottom of the cup is perforated and the brim is cut. The metal spout thus formed with its circumferential lip and circumferential brim is finally given its final shape by knurling the tapered region. During press-knurling, the deep-drawn spout is pressed against another die (knurled wheel) so that both of them are rotating. The shape of the die is transferred to the spout, wherein the bead and the groove(s) are incorporated. This way round edges are formed for the groove zone(s) and the bead zone(s).

The riser body may be formed of any insulating and/or exothermic material known in prior art to ensure that the molten metal in the riser solidifies later than the casting itself. For example, exothermic materials, as disclosed in DE 19925167 A1 , are conceivable as possible riser materials. Risers made of insulating material are also common and feasible. Conceivable as possible materials are familiar to those skilled in the art. Depending on the particular casting, exothermic and/or insulating risers may be preferred. The riser body can have a lid opening with a lid. The lid opening and the riser opening are arranged in the riser body on opposite surfaces thereof. In particular, the riser body is made of two parts, e.g., the riser bowl and the riser lid.

The invention will now be further illustrated with reference to the following figures. In the figures,

Fig. 1 is a longitudinal section through the riser with movable spout, the spout being in the form of a tubular body in an extended position;

Fig. 2 is a longitudinal section through the riser with the tubular body partially pushed into the riser cavity; and

Fig. 3 is a longitudinal section through the riser with the tubular body pushed into the riser cavity;

Fig. 4 is a top view of a spout with bead, first and second grooves in the tapered portion, as seen perpendicular to the spout axis;

Fig. 5 is a section through the spout according to Fig. 3 along the spout axis with auxiliary lines to illustrate the horizontal surfaces and enveloping surfaces; and

Fig. 6 is a 3D view of the spout according to Fig. 3 in a tilted position.

Figs. 1 to 3 only serve to illustrate the movement of the spout and to represent the spout in the riser body. In the tapered region, the spout is shown only schematically so that the first and second grooves and the bead are not visible. The grooves and the bead are shown in Figs. 4 to 6, more particularly in Fig. 5, where only the spout of the riser or a partial view of the spout is shown.

Fig. 1 is a longitudinal section through a riser according to the invention, running parallel to the spout axis 12. The riser consists of a riser body 1 and the spout 2. The riser body is made up of two parts, an upper riser part 3, which can also be referred to as a lid, and a lower riser part 4.

Together, the upper riser part 3 and the lower riser part 4 form the riser cavity 5 of the riser body 1 . Further, a recess 6 is provided in the upper riser part 3, which accommodates the tip of a pin 13 which is used to position the riser on a pattern plate. The upper riser part 3 and the lower riser part 4 are connected to each other by a bonding 7. A riser opening 8 is provided in the lower riser part 4, which allows inflow into and outflow from the riser cavity 5. The spout 2 is movably inserted into the riser opening 8. The spout 2 has a circular cross-section. At the end of the spout facing the riser cavity 5, a stop 9 is provided which goes around the outer circumference of the spout 2. The diameter of the spout 2 at the end facing the riser cavity 5 matches the diameter of the riser opening 8, so that the spout 2 can be pushed into or pulled out of the riser cavity 5. At its end facing away from the cavity, the spout 2 tapers in a tapered portion 10, which contributes to the formation of a breaking edge after the casting mould has been made. Fig. 1 shows the riser in a state in which the spout 2 has been fully moved out of the riser body 1 . In this case, the stop 9 comes into contact with the bottom 11 of the riser cavity 5 so that the spout 2 is prevented from falling out. Such a condition occurs, for example, when the riser is removed from its packaging and slipped over the pin and just before it rests on the end of the pin so that the spout 2 is moved out to its maximum. When the pin end of the pin 13 then rests on the ceiling surface of the upper riser part 3 in the recess 6, the spout 2 has already been pushed a small distance back into the riser cavity. The spout 2 is inserted into the riser opening of the riser body 1 such that only a small resistance occurs when the spout 2 is moved.

Fig. 2 shows a state in which the spout 2 is partially inserted into the riser body 1 and the compaction of the moulding material 16 surrounding the riser has been completed. Fig. 2 thus corresponds to a state that is assumed after the moulding material 16 has been compacted during the production of the casting mould. While the moulding material mixture is compacted, the riser body 1 moves towards the spout 2. Since the spout 2 rests with its tapered end on the pattern plate 14 of the mould pattern, the riser body 1 and the spout 2 move relative to each other, wherein the spout 2 itself does not move. As compared to Fig. 1 , the double arrow 15 shows how the distance between the lower edge of the riser body and the pattern plate 14 decreases in size from Fig. 1 to Fig. 2.

Fig. 3 shows a state that is assumed, for example, for shipping the riser according to the invention. Therein, the riser is turned around relative to the position shown in Fig. 1 , so that the spout 2 moves into the cavity 5 of the riser body 1 under the influence of gravity. Therein, the spout 2 comes to rest against the ceiling surface of the upper riser part 1 on the side of the cavity 5 opposite the riser opening 8. Therein, the length of the spout 2 is preferably selected such that the spout is completely received by the riser body 1 , so that the tapered portion 10 of the spout 2 does not protrude beyond the end of the riser opening 8. The spout can therefore not be damaged during transport.

Fig. 4 shows a top side view of the spout 2 with the tapered portion 10. In this enlarged figure, a bead 17 and first and second grooves 18,19 are visible. The bead 17 and the two grooves 18,19 are knurled to be incorporated into the tapered region 10. All transitions in the tapered region 10 are round transitions and not angular edges or angular butt edges of substantially straight surfaces. Above the tapered region 10, the tubular body of the spout 2 has a uniform diameter. At the end of the tubular body of the spout 2, the tube bends up in the form of a circumferential brim. The brim is the stop 9.

The second end region forms the shaft of the spout 2, which can enter the riser cavity 5 completely or partially. Fig. 5 shows an optional circumferential shaft bead 33 at the transition from the tapered region to the shaft portion, which can serve as a stop for inserting the spout 2 with its shaft portion through the riser opening 8 into the riser cavity 5 of the riser body 1 .

Fig. 5 shows a section through the spout 2 along the spout axis 12. The horizontal lines are the surfaces running perpendicular to the paper plane on which the spout axis stands as the surface normal. In the tapered region 10, the surfaces decrease in size towards the outlet 30, the tapered region 10 having zones comprising at least a first groove zone 28 and a bead zone 27 adjacent thereto, so that a sequence of surfaces orthogonal to the spout axis results in the tapered region, wherein the surfaces in the first groove zone 28 decrease in size and the surfaces in the transition area from the first groove zone 28 to the bead zone 27 initially increase in size to form an outwardly curving bead 17 and decrease in size again when the bead 17 subsides. The bead 17 is followed by a second groove 19, the first groove 18 causing a deeper constriction 24 (orthogonal to the spout axis) of the tapered region than the second constriction 25 (also orthogonal to the spout axis) relative to the second groove 19. In the same manner, the mean bead height 31 can be determined by means of a tangent for the bead height 32.

When a tangent 22' is applied to the highest point of the bead and brought up to the spout in the direction of the arrow so that the other end portion is applied to the nearest highest point in the direction of the second end portion, the plurality of such applied tangents 22 results in an enveloping surface in the plane of the spout axis and a first volume 20 under the enveloping surface. The constriction 24 then designates the mean depth of the first groove 18.

If a second groove 19 is provided, as shown in Fig. 5, a tangent 23 can again be applied, which is first applied to the highest point of the bead 17 and then to the spout in the direction of the outlet.

A plurality of such applied second tangents 23 in the plane of the spout axis results in a second enveloping surface and, under the second enveloping surface, a second volume 21. The constriction 25 then indicates the (mean) depth of the second groove 18.

Fig. 6 shows a lateral 3D view of the spout according to Fig. 3. The figure shows the stop 9 that rests on the bottom 11 of the riser cavity around the riser opening 8 when the spout is fully extended as shown in Fig. 1 . The stop 9 is shaped like a hat brim and bends approximately at right angles at the end of the second end portion (perpendicular to the spout axis). At the end of the tapered region 10 or the first end region, the spout 30 is visible, into which the circumferential lip 26 projects, the circumferential lip 26 bending approximately at right angles relative to the spout axis 12 to form a circumferential narrow stiffening rib. The lip 26 is placed on the base of the pin 13 or on the pattern plate 14. The pin then extends through the outlet 30 (both not shown). Also visible are the second groove 19 and the bead 17. List of reference

Riser body 1

Spout 2

Upper riser part I lid 3

Lower riser part 4

Riser cavity I cavity of the riser body 5

Recess in the lid I upper riser part 6

Bonding 7

Riser opening 8

Stop 9

Tapered portion 10

Bottom of the riser cavity 11

Spout axis 12

Pin / centring pin 13

Pattern plate 14

Double arrow: distance from the lower edge of the riser body to the pattern plate 15

Moulding material 16

Bead 17

First groove 18

Second groove 19

First volume 20

Second volume 21

First tangent to define the enveloping surface 22

First tangent (not yet applied on both sides) 22'

Second tangent to define the enveloping surface 23

First constriction 24

Second constriction 25

Lip 26

Bead zone 27

First groove zone 28

Second groove zone 29

Outlet 30

Bead height 31

Tangent for bead height 32

Shaft bead 33