Food tray insert with an outer contour featuring forward and backward curves

Description

[0001] The present invention relates to a feeder insert for insertion into a mold used in metal casting, comprising a feeder body made of an insulating and / or exothermic feeder material, wherein the feeder body has a circumferential and an outwardly directed outer contour, a feeder cavity bounded at least by the side wall for receiving liquid metal, and a feeder opening for connecting the feeder cavity to a mold cavity during the casting process. The feeder opening is generally formed in a bottom region of the feeder body, wherein the feeder cavity is bounded on the side opposite the bottom region by a lid region, wherein a further opening may be formed in the lid region.

[0002] In foundry technology, it is often necessary to incorporate additional feeder inserts into the molds. During casting, the feeder body fills with molten metal, compensating for volume deficits that occur during solidification and preventing shrinkage cavities. For this to work, the feeder inserts must be designed so that the molten metal solidifies later than the casting. This allows for material transport towards the casting during solidification, ensuring a dense supply. The so-called module of the feeder insert should be larger than the module of the respective node of the casting being poured. To achieve this, the feeder inserts feature a feeder cavity, defined by the feeder body, to hold the molten metal, as well as a feeder opening to connect this cavity to the mold cavity during the casting process.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.

[0003] Suitable material mixtures for the feeder material used to manufacture the feeder body are known from EP 0 888 199 B1. According to this patent, the exothermic material should comprise an oxidizable metal and an oxidizing agent capable of generating an exothermic reaction. It has also been proposed to add components of an insulating refractory material to the material mixture, resulting in an exothermic-insulating material mixture. In contrast to feeders made of exothermic material, the heat balance of purely insulating feeders is inferior due to the lack of active heat input during the solidification process.

[0004] In contrast to feeder bodies made from exothermic / insulating granular material, feeder bodies made from a pure metal core are also known. Such a dimensionally stable, metallic feeder is described, for example, in EP 1 864 729 A2. Since no exothermic reaction occurs in these feeder inserts, only their insulating effect is considered. Because the dimensionally stable metal core must not melt, it requires a suitable wall that draws heat away from the molten metal upon contact. This can lead to the formation of a thin, rim-like layer on the remaining metallic portion of the feeder. Furthermore, gases generated during the casting process cannot be vented, and so-called gas leaks or gas explosions can occur inside the feeder.

[0005] To increase the insulating effect of a feeder insert, it is known, for example, from EP 2 489 449 B1, to enclose a feeder body made of exothermic feeder material with a shell made of insulating refractory material. However, manufacturing such a shell made of refractory material is relatively expensive.

[0006] From EP 3 009 209 A1, it is therefore known to arrange air cavities completely surrounded by the feeder material inside the feeder body as an additional insulator. However, a disadvantage of such a design is that, in the event of an exothermic reaction of the feeder material arranged radially outside the air cavities, the resulting thermal energy is also insulated by the air cavities, so that the heat generated is transferred into the molding material surrounding the feeder insert. This is particularly disadvantageous because, during the exothermic reaction, a feeder insert burns from the inside out, and the thermal energy required for replenishment is lost at the end of the casting process.

[0007] To increase the module of a feeder insert, a feeder insert with an exothermic feeder body is known from EP 0 779 844 B1. In this feeder, the side wall of the feeder body curves convexly outwards from the upper wall section and transitions at the lower end into a passage section, also known as a feeder neck. The side wall has several ribs projecting into the interior, which transition at their ends into the upper wall or the passage section. 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 manufacturing is more complex.

[0008] From DE 101 56 571 C1, US 2001 / 026036 A1, GB 2 141 649 A and JP 2013 215799 A, a feeder body with external contour projections is known, which are designed to support a shell or to hold the feeder body in a receptacle of a casting mold.

[0009] Since today's castings are becoming increasingly demanding with regard to their feeding during the casting process due to increasingly complex shapes, and since the spatial positioning of feeder inserts in the molds is also becoming increasingly difficult, the present invention aims to provide a feeder insert that offers a higher modulus in an alternative way with the same feeder mass and feeder cavity volume.

[0010] The problem is solved by a feeder insert with the features of the independent claim. Advantageous embodiments of the feeder insert are specified in the dependent claims and in the entire description, whereby individual features of the advantageous embodiments can be combined with one another in any technically meaningful way.

[0011] The problem is solved in particular by a feeder insert with the features mentioned above, 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, wherein the outer contour projections and / or the outer contour recesses have a height or depth that is at least 5% of a maximum outer diameter of the feeder body and that a distance between mutually facing lateral surfaces of adjacent outer contour projections or between mutually facing lateral surfaces of an outer contour recess in the circumferential direction is at most 8% of the maximum outer diameter of the feeder body.

[0012] The basic idea of ​​the invention is therefore that many regularly or irregularly arranged, locally projecting projections (raised areas) and / or locally recessed depressions (recesses) are formed on the radially outwardly oriented outer surface of the feeder body. With appropriate dimensions of the feeder body, it exhibits in

[0013] Compared to conventional feeder bodies (without external projections and recesses), this design offers either a higher module for the same weight or volume of the feeder body, or the same module for a lower weight or smaller volume. Furthermore, such a feeder insert can only be placed into a recess in the mold after the mold has been manufactured, ensuring that at least an insulating air gap remains between the surface of the recess and the outer contour of the feeder body, adjacent to the external contour projections. These external contour projections can also serve as support points / surfaces for a cover described below.

[0014] Particularly during 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 recesses around the feeder body heats up more intensely in some areas, creating thermal bridges between two adjacent outer contour projections. These thermal bridges ensure that, despite the increased outer surface area of ​​the feeder body due to the outer contour projections / recesses, heat transfer from the heated molding material, which has poor thermal conductivity, into the mold is reduced, thus enhancing the insulating effect. The exothermic energy of the feeder body is therefore utilized more effectively, and the proportion of energy unintentionally transferred to the mold is reduced, despite the significantly larger outer surface area of ​​the feeder body. This also increases the energy transferred to the liquid metal in the feeder cavity.

[0015] The feeder body is in particular made of granular and / or fibrous feeder material and preferably made of exothermic material, thus comprising at least one oxidizable material, for example an oxidizable metal, an oxidizing agent, possibly fillers and / or fibers as well as a binder.

[0016] In principle, the outer contour projections and / or recesses can have any shape. For example, they can be cube-shaped, cuboid-shaped, dome-shaped, pyramid-shaped, or trapezoidal in cross-section, with rounded edges. Specifically, to create a bearing surface for the casing, the outward-facing surface of the outer contour projection is also curved circumferentially at the corresponding point, corresponding to the radius of the feeder body.

[0017] The outer contour projections and / or the outer contour recesses have a height or depth that is at least 5%, preferably at least 10% and at most 45%, preferably at most 20% of the maximum outer diameter of the feeder body.

[0018] In particular, to form a thermal bridge between two adjacent external contour projections or in an external contour recess, the lateral surfaces of the external contour projections / recesses extend both longitudinally and radially, so that lateral surfaces of circumferentially offset and adjacent external contour projections, or two lateral surfaces of exactly one external contour recess, face each other directly in the circumferential direction, and the surfaces may also be aligned parallel to each other. The height / depth can be selected accordingly. The distance between the facing lateral surfaces is, in the circumferential direction, at least 2%, preferably at least 4%, and at most 8%, preferably at most 6%, of the maximum outer diameter of the feeder body.

[0019] For ease of manufacturing, the outer contour projections and / or recesses preferably extend elongated in one direction, and in particular along a longitudinal axis of the feeder body defined by the feeder opening. The elongated outer contour projections / recesses extend, in particular, from the bottom or top area. The cross-sectional shape of the elongated outer contour projections and / or recesses can be arbitrary, but is preferably rectangular or triangular, optionally with rounded edges. In particular, to form a bearing surface for the casing, the outwardly facing surface of the elongated outer contour projection is also curved circumferentially at the corresponding point, corresponding to the radius of the feeder body.

[0020] In a preferred embodiment, the outer contour projections and / or outer contour recesses extend along the entire side wall of the feeder body.

[0021] Preferably, the elongated outer contour projections and / or recesses are arranged uniformly one behind the other in the circumferential direction, with a total of at least 3, preferably at least 6, outer contour projections and / or recesses being provided. If the elongated outer contour projections and / or recesses are intended to form thermal bridges, at least 12 or at least 16 outer contour projections and / or recesses may be provided. If, on the other hand, the elongated outer contour projections and / or recesses are intended to form bearing surfaces for the casing, at most 9 or at most 6 outer contour projections and / or recesses may 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.Thus, a corresponding core box for the production of a feeder body can have elongated recesses / projections corresponding to the outer contour projections and / or outer contour recesses on its inner surface which defines the outer contour.

[0022] In this context, it is particularly preferred if the width of the outer contour projections and / or the outer contour recesses, and / or the distance between adjacent outer contour projections / recesses, changes along their length, especially along the longitudinal axis of the feeder body. In particular, the distance between two adjacent outer contour projections decreases from the bottom region of the feeder body to the top region. This is also particularly advantageous if an inner contour of the feeder body facing the feeder cavity tapers in its cross-sectional design from the bottom region containing the feeder opening to the opposite top region. The inner contour thus does not have a concave shape. Therefore, the feeder body can be manufactured in one piece in a single process step without a lost core.

[0023] The outer contour projections extending along the longitudinal axis of the feeder body are designed in such a way that they are arranged directly adjacent to each other in the circumferential direction of the feeder body, with the feet of the projections (in their cross-sectional design) merging directly into one another.

[0024] Thus, a feeder body manufactured in a corresponding core box can be removed from the core box along its longitudinal axis after its production. Accordingly, the core box has straight, tapered projections or recesses extending in one direction on its inner surface, which defines the outer contour of the feeder body.

[0025] In one embodiment of the invention, the feeder insert comprises a casing, the casing surrounding the outer contour of the feeder body at least along a portion of its longitudinal extent and abutting the outer contour, such that at least one cavity is formed between the casing and the outer contour, which has the outer contour projections and / or recesses. The casing surrounding the feeder body radially extends from the bottom region over at least half the length of the feeder body in its longitudinal direction. Preferably, the casing surrounding the feeder body extends over two-thirds of the length of the feeder body or even over the entire length of the feeder body. Preferably, the inner surface of the sleeve-shaped or pot-shaped casing abuts the radially outermost points of all outer contour projections.

[0026] The casing and outer contour of the feeder body thus define a cavity, which is preferably closed on both sides along the longitudinal direction of the feeder body. The casing therefore prevents molding material from entering this cavity during the molding process. The cavities provide insulation.

[0027] The casing is formed in particular from a dimensionally stable body such as a metal sheet or a suitable plastic, wherein the casing can have a wall thickness of a maximum of 2 mm [millimeters], particularly preferably a maximum of 1 mm. In particular, the casing is manufactured by a deep-drawing process.

[0028] In a preferred embodiment, the casing has a bottom section that extends over the end face of the feeder body in the bottom region of the feeder body and, in particular, is at least partially in contact with the bottom region of the feeder body. The casing has an opening in the bottom section corresponding to the feeder opening of the feeder body, the opening of the casing being smaller than the feeder opening. In this way, the casing simultaneously provides a (metallic) breaker core that constricts the connection between the feeder opening and the casting, thus defining a predetermined breaking point for the metallic feeder remnant located in the feeder cavity after the casting process. The bottom section of the casing can be designed to taper from the feeder opening of the feeder body to its opening facing the casting.The casing, which circumferentially surrounds the feeder body, and the bottom section of the casing, which forms the crushing core, can thus be manufactured as a single piece. The casing can then be attached to the feeder body (which is primarily a single piece) in a second process step.

[0029] The casing can be connected to the food processor body, particularly in the base and / or lid area, either by a material bond, for example by adhesive, or by a force-fit bond.

[0030] In a further embodiment, it can also be provided that the outer contour projections have a chamfer on their (front) side facing the feeding opening, wherein, in particular, projections adjacent in the circumferential direction can have different angles of the chamfer.

[0031] In a radial direction, the protrusions can be pointed or rounded.

[0032] The invention and its technical context are explained below with reference to the figures, which show preferred embodiments of the invention. They schematically depict Figure 1: a longitudinal section view through a feeder body, Figure 2: a top view of the feeder body according to Figure 1 Figure 3: the food bowl according to Figure 1 with a casing in longitudinal section and Figure 4: a top view of the feeder body with casing according to Figure 3 .

[0033] The figures show a feeder body 1, which has a circumferential side wall 2 extending from a base area 11 along a longitudinal axis 7 to a lid area 12. The side wall 2, with an inner contour 14, defines a feeder cavity 4. A feeder opening 5 adjoins the feeder cavity 4, through which the feeder cavity 4 is connected to the mold cavity of the casting mold during the casting process.

[0034] The side wall 2 has an outer contour 3 on its outer surface 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 extend from the bottom area 13 over approximately three-quarters of the length of the feeder body 1. The feeder body 1 thus has a lamellar outer contour in its lower area.

[0035] As especially 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 bottom area 11 to the top area 12, so that the width of a cavity 10 between two adjacent outer contour projections 6 decreases.

[0036] It can be seen that the cross-sectional design of the inner contour 14 tapers from the bottom area 11, which has the feeder opening 5, along the longitudinal axis 7 towards the cover area 12. It is therefore possible to manufacture the feeder body 1 in a single process step without a lost core in a core box.

[0037] In the Figure 1 and 2 In the feeder body 1 shown, molding material enters the space between the outer contour projections 6 of the mold during the casting process. If an exothermic reaction of the feeder material occurs during the casting process, the molding material located on and between the outer contour projections 6 heats up, forming thermal bridges between adjacent outer contour projections 6. These thermal bridges reduce heat transfer to the surrounding molding material, thus increasing the modulus of the feeder insert.

[0038] The one in the Figures 3 and 4The illustrated feeder insert, in addition to the feeder body 1, has a casing 9 that circumferentially surrounds the lower area of ​​the feeder body 1 in the region of the outer contour projections 6. The inner side of the casing 9 rests against the outer sides 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, with an opening 13 in the casing 9 being smaller than the feeder opening 5.

[0039] The shell 9 prevents molding material from entering between the outer contour projections 6 during the molding process, thus forming air-filled cavities 10 that are bounded by adjacent outer contour projections 6 and the shell 9, as well as at their upper ends by the feeder body 1 itself. These cavities 10 provide insulation during the casting process.

[0040] Due to the formation of thermal bridges between adjacent outer contour projections 6 during the casting process in the embodiment according to Figure 1 and 2 or by the cavities 10 bounded by the shell 9 in the embodiment according to Figures 3 and 4 The module of the food inserts is increased while maintaining the same food weight or food body volume. Reference symbol list

[0041] 1 Food cabinet 2 Side wall 3 Outer contour 4 Food cavity 5 Food opening 6 Outer contour projection 7 Longitudinal axis 8 Width 9 Shell 10 Cavity 11 Bottom area 12 Lid area 13 Opening 14 Inner contour

Claims

1. Feeder sleeve for insertion into a casting mould used in the casting of metals, comprising a feeder body consisting of an insulating and / or exothermic feeder material (1), comprising - a circumferential side wall (2), wherein the side wall (2) has an outwardly directed outer contour (3), - a feeder cavity (4) limited at least by the side wall (2) for holding liquid metal, and - a feeder opening (5) for connecting the feeder cavity (4) with a mould cavity of the casting mould during the casting process, wherein the outer contour (3) comprises a plurality of outer contour projections (6) and / or outer contour recesses, wherein the outer contour projections (6) and / or the outer contour recesses have a height or depth that is at least 5% of a maximum outer diameter of the feeder body (1) and that a distance of directly facing lateral surfaces of adjacent outer contour projections (6) or directly facing lateral surfaces of an outer contour recess in circumferential direction is no more than 8% of the maximum outer diameter of the feeder body (1).

2. The feeder sleeve 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 feed body (1) defined by the feeder opening (5).

3. The feeder sleeve 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).

4. The feeder sleeve according to any one of the preceding claims, wherein a width of the outer contour projections (6) and / or of the outer contour recesses varies along their length.

5. The feeder sleeve according to any of the preceding claims, wherein the feeder sleeve comprises a shell (9), wherein the sheath (9) surrounds the outer contour (3) at least in sections and rests externally on the outer contour (3), so that at least one cavity (10) is formed between the sheath (9) and the outer contour (3) having the outer contour projections (6) and / or outer contour recesses.

6. The feeder sleeve according to Claim 5, wherein the sheath (9) is formed of a dimensionally stable body such as metallic sheet metal.

7. The feeder sleeve according to Claim 5 or 6, wherein the sheath (9) extends over a bottom area (11) of the feeder body (1) having the feeder opening (5) and has an opening (13) assigned to the feeder opening (5) of the feeder body (1), wherein the opening (13) of the sheath (9) is smaller than the feeder opening (5).

8. The feeder sleeve according to any one of the preceding claims, wherein the outer contour projections (6) comprise a chamfer on the side facing the feeder opening (5), wherein in particular adjacent projections (6) comprise different angles of the chamfer.

9. The feeder sleeve according to any one of the preceding claims, wherein a cross-sectional design of the inner contour (14) is tapered from the feeder opening (5) along the longitudinal axis (7).

10. The feeder sleeve according to any one of the preceding claims, wherein the outer contour projections (6) taper to a point or are rounded in the radial direction.

11. The feeder sleeve according to any one of the preceding claims, wherein the feeder body (1) is designed as a single piece.