EP3756788A1 - Feeder insert with outer contour having recesses and protrusions - Google Patents

Abstract

The present invention relates to a feeder insert for insertion into a casting mold used in the casting of metals, comprising a feeder body (1) consisting of an insulating and / or exothermic feeder material, having a circumferential side wall (2), the side wall (2) having an after outwardly directed outer contour (3), - a feeder cavity (4) bounded at least by the side wall (2) for receiving liquid metal and - a feeder opening (5) for connecting the feeder cavity (4) to a mold cavity of the casting mold during the casting process., wherein the outer contour (3) has a plurality of outer contour projections (6) and / or outer contour recesses.

Description

The present invention relates to a feeder insert for insertion into a casting mold used in the casting of metals, comprising a feeder body consisting of an insulating and / or exothermic feeder material, the feeder body having a circumferential and outwardly directed outer contour, one at least limited by the side wall Feeder cavity for receiving liquid metal and a feeder opening for connecting the feeder cavity to a mold cavity of the casting mold during the casting process. The feeder opening is generally formed in a bottom area of the feeder body, the feeder cavity being delimited by a cover area on the side opposite the bottom area, with a further opening being able to be formed in the cover area.

In foundry technology, it is often necessary to arrange additional feeder inserts in the casting molds, the feeder body of which fills with the liquid metal when the casting is poured and compensates for any volume deficits that occur during the solidification of the casting, in order to prevent voids in the casting. For this purpose, the feeder inserts must be designed in such a way that the liquid metal fed into them solidifies later than the casting so that material can be transported to the casting during the solidification process, which tightly feeds the casting. The so-called Module of the feeder insert must be larger than the module of the respective node point of the casting to be cast. For this purpose, the feeder inserts have the feeder cavity delimited by the feeder body for receiving liquid metal and a feeder opening for connecting the feeder cavity to the mold cavity of the casting mold during the casting process. In order to ensure the subsequent solidification of the liquid metal entering the feeder cavity, the feeder cavity consists of an exothermic and / or insulating feeder material.

From the EP 0 888 199 B1 Suitable material mixtures for the feeder material for producing the feeder body are known. Accordingly, the exothermic material should comprise an oxidizable metal and an oxidizing agent, which can produce an exothermic reaction, it has also already been proposed to add constituents of an insulating refractory material to the material mixture, so that an exothermic-insulating material mixture results. In contrast to feeders made of exothermic material, the heat balance of pure insulating feeders is worse due to the lack of an active heat supply during the solidification process.

In contrast to feeder bodies made of exothermic / insulating granular feeder material, feeder bodies made of a pure metal body are also known. Such a dimensionally stable, metallic feeder is for example in EP 1 864 729 A2 described. Since there is no exothermic reaction with these feeder inserts, only the insulating effect is taken into account. Since the dimensionally stable metal body must not melt, it requires a corresponding wall that removes heat from the liquid metal when it is touched, which can lead to the formation of edge shells on the metal feeder residue. In addition, gases generated during the casting process cannot be discharged and so-called gas defects or gas explosions can occur inside the feeder.

To increase the insulating effect of a feeder insert, for example, is off EP 2 489 449 B1 known to enclose a feeder body made of exothermic feeder material with a shell made of insulating refractory material. However, the manufacture of such a shell made of refractory material is relatively expensive.

Out EP 3 009 209 A1 It is therefore known to arrange air cavities completely surrounded by the feeder material in the interior of the feeder body as an additional insulator. However, a disadvantage of such a configuration is that in the event of an exothermic reaction of the feeder material arranged radially on the outside of the air cavities, the resulting thermal energy is also isolated by the air cavities, so that the resulting heat is released into the molding material surrounding the feeder insert. This is particularly disadvantageous since a feeder insert burns from the inside out during the exothermic reaction and the thermal energy required for the make-up is lost at the end of the casting process.

To increase the module of a feeder insert is off EP 0 779 844 B1 a feeder insert is known with an exothermic feeder body, in which the side wall of the feeder body extends convexly outwards starting from the upper wall part and merges at the lower end into a passage part also known as the feeder neck, the side wall having several ribs protruding into the interior, which at the ends merge into the upper wall or the passage part. The feeder body can either be assembled from several separately manufactured parts or manufactured in one piece using a lost core. However, the use of a lost core in production is expensive.

Since today's castings are on the one hand more complex with regard to their feeding during the casting process and on the other hand the spatial positioning of feeder inserts in the casting molds is becoming more and more difficult, the object of the present invention is to provide a feeder insert that can be used in an alternative way provides a higher module with the same feeder mass and the same feeder cavity volume.

The problem is solved by a feeder insert with the features of the independent claim. Advantageous refinements of the feeder insert are specified in the dependent claims and in the entire description, with individual features of the advantageous refinements being able to be combined with one another in a technically meaningful manner.

The object is achieved in particular by a feeder insert with the features mentioned at the beginning, in which the outer contour has a plurality (at least three, preferably at least five or particularly preferably at least ten) of outer contour projections and / or outer contour recesses.

The basic idea of the invention therefore provides that many regularly or irregularly arranged, locally protruding protrusions (elevations) and / or locally recessed recesses (depressions) are formed on the radially outwardly oriented outer side of the feeder body. With a corresponding dimensioning of the feeder body, compared to conventional feeder bodies (without protrusions and recesses on the outside), it has either a higher module with the same weight or the same volume of the feeder body or the same module with a lower weight or smaller volume of the feeder body. In addition, such a feeder insert can only be used after the production of the casting mold are inserted into a receptacle provided for the feeder insert in the casting mold, so that at least one insulating air cavity remains between the surface of the receptacle of the casting mold and the outer contour of the feeder body adjacent to the outer contour projections. The outer contour projections can also serve as support points / surfaces for an envelope described below.

In particular in the case of an exothermic reaction of the feeder material forming the outer contour during the casting process, the molding material adjacent to the outer contour projections or outer contour recesses is locally more heated around the feeder body, whereby thermal bridges are formed between two adjacent outer contour projections. The thermal bridges ensure that, despite the outer surface of the feeder body enlarged by the outer contour projections / outer contour recesses, the heat dissipation through the heated molding material, which has poor thermal conductivity, is reduced into the casting mold, which increases the insulating effect. The exothermic energy of the feeder body is thus used more effectively and the proportion of the energy released into the casting mold unintentionally is reduced despite the much larger outer surface of the feeder body on the molding material. However, this also increases the energy given off to the liquid metal in the feeder cavity.

The feeder body is made in particular of granular and / or fibrous feeder material and is preferably made of exothermic material, thus comprises at least one oxidizable material, for example an oxidizable metal, an oxidizing agent, possibly fillers and / or fibers and a binding agent.

In principle, the external contour projections and / or external contour recesses can have any shape. Thus, the outer contour projections / outer contour recesses can, for example, be cube-shaped, cuboid, dome-shaped, pyramidal or trapezoidal in section, with the edges being able to be rounded. In particular to form a support surface for the casing, the outwardly directed surface of the outer contour projection is also curved in the circumferential direction at the corresponding point in accordance with the radius of the feeder body.

The outer contour projections and / or the outer contour recesses have a height or a depth that is in particular at least 5%, preferably at least 10% and at most 45%, preferably at most 20% of the maximum outer diameter of the feeder body.

In particular to form a thermal bridge between two adjacent outer contour projections or in an outer contour recess, lateral surfaces of the outer contour projections / outer contour recesses extend both in the longitudinal direction and in the radial direction, so that lateral surfaces of outer contour projections offset in the circumferential direction and adjacent to one another or two lateral surfaces of exactly one outer contour recess in Circumferential direction are facing each other directly, wherein the surfaces can also be aligned parallel to each other. In particular, the height / depth can be selected accordingly for this purpose. The distance between the facing lateral surfaces in the circumferential direction is in particular at least 2%, preferably at least 4% and at most 8%, preferably at most 6% of the maximum outside diameter of the feeder body.

For simple production, the outer contour projections and / or outer contour recesses preferably extend elongated in one direction and in particular along a longitudinal axis of the defined by the feeder opening Feeder body. The elongated external contour projections / external contour recesses extend, in particular, starting from the base area or the cover area. The cross-sectional design of the elongated external contour projections and / or external contour recesses can be arbitrary, but is preferably rectangular or triangular, optionally with rounded edges. In particular, to form a support surface for the casing, the outwardly directed surface of the elongated outer contour projection is also curved in the circumferential direction corresponding to the radius of the feeder body at the corresponding point.

In a preferred embodiment, the outer contour projections and / or outer contour recesses each extend along the entire side wall of the feeder body.

The elongated outer contour projections and / or outer contour recesses are preferably arranged uniformly one behind the other in the circumferential direction, it being possible for a total of at least 3, preferably at least 6, outer contour projections and / or outer contour recesses to be provided. If the elongated outer contour projections and / or outer contour recesses are provided for forming thermal bridges, at least 12 or at least 16 outer contour projections and / or outer contour recesses can also be provided. If, on the other hand, the elongated outer contour projections and / or outer contour recesses are provided for the formation of bearing surfaces for the casing, a maximum of 9 or at most 6 outer contour projections and / or outer contour recesses can also be provided. In this case, the outer contour of the feeder body has a lamellar shape. Such a feeder body is particularly easy to manufacture in a single process step. So can a corresponding core box for production of a feeder body have elongated recesses / projections corresponding to the outer contour projections and / or outer contour recesses on its inner surface which defines the outer contour.

In this context, it is particularly preferred if a width of the outer contour projections and / or the outer contour recesses and / or a distance between adjacent outer contour projections / outer contour recesses changes along their length, in particular along the longitudinal axis of the feeder body. In particular, a distance between two adjacent outer contour projections decreases from the bottom area of the feeder body to the cover area. This is also particularly advantageous if an inner contour of the feeder body facing the feeder cavity tapers in its cross-sectional configuration, starting from the base area having the feeder opening, to the opposite cover area. The inner contour therefore does not have a concave shape. The feeder body can thus be manufactured in one piece in a single process step without a lost core.

The outer contour projections extending along the longitudinal axis of the feeder body are designed in particular so that they are arranged directly adjacent to one another in the circumferential direction of the feeder body, the feet of the projections (in their cross-sectional configuration) merging directly into one another.

A feeder body produced in a corresponding core box can thus be removed from the core box in the direction of the longitudinal axis after its production. The core box accordingly has, on its inside, which defines the outer contour of the feeder body, projections or recesses that taper in one direction and extend in a straight line.

In one embodiment of the invention it is provided that the feeder insert comprises a casing, the casing surrounding the outer contour of the feeder body at least along part of the longitudinal extension of the feeder body and resting on the outside of the outer contour, so that between the casing and the outer contour projections and / or Outer contour recesses having outer contour is formed at least one cavity. The casing surrounding the feeder body radially on the outside in the circumferential direction preferably extends from the bottom region over at least half the length of the feeder body in its longitudinal direction. The casing surrounding the feeder body in the circumferential direction preferably extends over two thirds of the length of the feeder body or even over the entire length of the feeder body. The sleeve-shaped or pot-shaped casing preferably rests with its inner surface on the radially outermost points of all the outer contour projections.

A cavity is thus delimited by the casing and the outer contour of the feeder body, which cavity is preferably closed on both sides in the longitudinal direction of the feeder body. The shell thus prevents molding material from getting into the cavity thus formed during the molding process of the casting mold. The cavities provide insulation.

The shell is in particular formed from a dimensionally stable body such as a metal sheet or a suitable plastic, wherein the shell can have a wall thickness of a maximum of 2 mm [millimeters], particularly preferably a maximum of 1 mm. In particular, the shell is produced in a deep-drawing process.

In a preferred embodiment, the casing has a base section which extends over the end face of the feeder body in the base area of the feeder body extends and in particular is in contact with the bottom region of the feeder body at least in sections, the casing having an opening assigned to the feeder opening of the feeder body in the bottom section, the opening of the casing being smaller than the feeder opening. In this way, a (metallic) breaker core is simultaneously provided by the shell, which constricts the connection between the feeder opening and the casting and thus defines a predetermined breaking point for the metal feeder residue located in the feeder cavity after the casting process. The bottom section of the shell can be designed in such a way that, starting from the feeder opening of the feeder body, it tapers to its opening facing the casting. The casing of the casing surrounding the feeder body in the circumferential direction and the bottom section of the casing forming the breaker core can thus be manufactured in one piece. The casing can thus be attached to the in particular one-piece feeder body in a second process step after it has been produced.

The casing can be connected to the feeder body in particular in the base area and / or cover area, in particular in a materially bonded manner, for example by means of adhesive, or in a non-positive manner.

In a further embodiment it can also be provided that the outer contour projections have a bevel on their (front) side facing the feeder opening, wherein in particular projections adjacent in the circumferential direction can have different angles of the bevel.

In the radial direction, the projections can be pointed or rounded.

Figur 1:

eine Längsschnittansicht durch einen Speiserkorpus,

Figur 2:

eine Draufsicht auf den Speiserkorpus gemäß Figur 1,

Figur 3:

den Speiserkorpus gemäß Figur 1 mit einer Hülle im Längsschnitt und

Figur 4:

eine Draufsicht auf den Speiserkorpus mit Hülle gemäß Figur 3.

The invention and the technical environment are explained below with reference to the figures, the figures showing preferred embodiments of the invention. It show schematically

Figure 1:

a longitudinal sectional view through a feeder body,

Figure 2:

a plan view of the feeder body according to Figure 1 ,

Figure 3:

the feeder body according to Figure 1 with a shell in longitudinal section and

Figure 4:

a plan view of the feeder body with casing according to Figure 3 .

The figures show a feeder body 1 which has a circumferential side wall 2 which extends from a base area 11 along a longitudinal axis 7 to a cover area 12. The side wall 2 delimits a feeder cavity 4 with an inner contour 14. A feeder opening 5 adjoins the feeder cavity 4, via which the feeder cavity 4 is connected to the mold cavity of the casting mold during the casting process.

The side wall 2 has on its outside an outer contour 3 with a plurality of outer contour projections 6 extending along the longitudinal axis 7, which are arranged one behind the other in the circumferential direction of the feeder body 1 and, starting from the bottom area 13, extend over approximately three quarters of the length of the feeder body 1 . The feeder body 1 thus has a lamellar outer contour in the lower area.

Like in particular from Figure 2 As can be seen, the outer contour projections 6 have a width 8 which increases along the longitudinal axis 7 from the base area 11 to the cover area 12, so that the width of a cavity 10 between two adjacent outer contour projections 6 decreases.

It can be seen that the cross-sectional design of the inner contour 14 tapers, starting from the base region 11 having the feeder opening 5, along the longitudinal axis 7 towards the cover region 12. It is thus possible to manufacture the feeder body 1 in a single process step without a lost core in a core box.

The one in the Figures 1 and 2 The feeder body 1 shown, during the molding process of the casting mold, the molding material gets between the outer contour projections 6.If there is an exothermic reaction of the feeder material during the casting process, the molding material located on the outer contour projections 6 and in between heats up, with thermal bridges being formed between adjacent outer contour projections 6. The heat bridges reduce the heat dissipation into the surrounding molding material, so that the module of the feeder insert is increased.

The one in the Figures 3 and 4th The feeder insert shown has, in addition to the feeder body 1, a sleeve 9 which surrounds the lower area of the feeder body 1 in the area of the outer contour projections 6 in the circumferential direction. The inside of the casing 9 lies against the outside of the outer contour projections 6 in the area of the side wall 2. The casing 9 also covers the bottom area 11 of the feeder body 1, an opening 13 of the casing 9 being smaller than the feeder opening 5.

The sleeve 9 prevents molding material from getting between the outer contour projections 6 during the molding process, so that air-filled cavities 10 are formed which are delimited by adjacent outer contour projections 6 and the sleeve 9 and at their upper ends by the feeder body 1 itself. These cavities 10 provide insulation during the casting process.

Through the formation of thermal bridges between adjacent outer contour projections 6 during the casting process in the embodiment according to FIG Figures 1 and 2 or by the cavities 10 delimited by the shell 9 in the embodiment according to FIG Figures 3 and 4th the module of the riser inserts is increased with the same riser weight or the same riser body volume.

List of reference symbols

1

Feeder body

2

Side wall

3

Outer contour

4th

Feeder cavity

5

Feeder opening

6th

Outer contour protrusion

7th

Longitudinal axis

8th

width

9

Shell

10

cavity

11

Floor area

12th

Lid area

13

opening

14th

Inner contour

Claims (11)

A feeder insert for insertion into a casting mold used in the casting of metals, comprising a feeder body (1) consisting of an insulating and / or exothermic feeder material - A circumferential side wall (2), the side wall (2) having an outwardly directed outer contour (3), - One at least by the side wall (2) delimited feeder cavity (4) for receiving liquid metal and - A feeder opening (5) for connecting the feeder cavity (4) to a mold cavity of the casting mold during the casting process, characterized in that the outer contour (3) has a plurality of outer contour projections (6) and / or outer contour recesses. Feeder insert according to claim 1, wherein at least some outer contour projections (6) and / or outer contour recesses each extend along a longitudinal axis of the feeder body (1) defined by the feeder opening (5). Feeder insert according to claim 2, wherein at least some outer contour projections (6) and / or outer contour recesses each extend along the entire side wall (2) of the feeder body (1). Feeder insert according to one of the preceding claims, wherein a width of the outer contour projections (6) and / or the outer contour recesses changes along their length. Feeder insert according to one of the preceding claims, wherein the feeder insert comprises a sheath (9), wherein the sheath (9) surrounds the outer contour (3) at least in sections and rests on the outside of the outer contour (3) so that between the sheath (9) and the outer contour (3) having the outer contour projections (6) and / or outer contour recesses is formed at least one cavity (10). Feeder insert according to claim 5, wherein the casing (9) is formed from a dimensionally stable body such as sheet metal. Feeder insert according to Claim 5 or 6, the casing (9) extending over a bottom area (11) of the feeder body (1) having the feeder opening (5) and having an opening (13) assigned to the feeder opening (5) of the feeder body (1) , wherein the opening (13) of the casing (9) is smaller than the feeder opening (5). Feeder insert according to one of the preceding claims, wherein the outer contour projections (6) have a bevel on the side facing the feeder opening (5), wherein in particular adjacent projections (6) have different angles of the bevel. Feeder insert according to one of the preceding claims, wherein a cross-sectional configuration of the inner contour (14) tapers starting from the feeder opening (5) along the longitudinal axis (7). Feeder insert according to one of the preceding claims, the outer contour projections (6) tapering to a point or rounded in the radial direction. Feeder insert according to one of the preceding claims, wherein the feeder body (1) is constructed in one piece.

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