Shield Feeder or Plug Feeder

Abstract

The invention relates to a feeder insert for inserting into a casting mold used for casting metals, comprising a feeder body 1, which extends along a longitudinal axis 13 of the feeder and has a feeder cavity 2, comprising a bottom side that can be inserted into the casting mold and a top side 7 that is situated opposite the bottom side. According to the invention, an energy absorbing device (8, 9) is provided on the top side 7 of the feeder body 1.

Description

The invention relates to a feeder insert for inserting into a casting mold used for casting metals, comprising a feeder body, which extends along a main axis of the feeder and has a feeder cavity, comprising a bottom side that can be inserted into the casting mold and a top side that is situated opposite the bottom side.

In the production of molded parts in a foundry, liquid metal is introduced into a casting mold. During the solidifying process, the volume of the material introduced decreases. Therefore, so-called feeders, i.e. open or closed spaces, are regularly inserted in or on the casting mold in order to compensate for the volume deficit during the solidification of the casting and to prevent the formation of voids in the casting. For this purpose, the feeders are connected to the casting or to the region of the casting that is at risk and are usually arranged above or to the side of the mold cavity.

In the production of the casting mold, firstly a pattern plate which corresponds to the inner contour of the mold cavity is produced. At the locations at which a feeder insert is to be fitted, a holding device is usually provided, for example a pin for fixing the position of the feeder insert. Once the feeders are fitted on the pattern plate, a molding material, generally molding sand, is applied to the pattern plate in such a way that the feeder insert is encapsulated. In a further step, the molding material is then compacted, so that the feeder is enclosed by the compacted molding material. During the compaction of the molding material, relatively high compaction pressures are used. There is therefore the risk that the feeder insert will not withstand the compressive forces occurring during the compaction and will break up. As a result, it is no longer possible for controlled feeding of the casting to take place during the casting process. It has been attempted to counter this problem by using particularly stable and thick-walled feeder inserts. However, this is quite expensive because of the increased material requirement.

Another approach is to absorb the compressive forces occurring during the compression molding by means of so-called expansion mandrels. Expansion mandrels generally comprise a tubular element for fastening on the pattern plate, a spring arranged in the tubular element and a mandrel tip element, which rests on the spring and can be displaced telescopically in the longitudinal direction. After the expansion mandrel is fastened on the pattern plate, a feeder insert is placed on it, the bottom surface of which is at a certain distance from the surface of the pattern in the initial arrangement, i.e. before the molding material is introduced. During the subsequent introduction and compaction of the molding material, the feeder insert is moved in the direction of the surface of the pattern against the spring force exerted by the expansion mandrel, without the bottom side of the feeder insert coming into direct contact with the surface of the pattern.

Therefore, destruction of the feeder insert is prevented even when high compaction forces are used.

A sprung mandrel for holding feeders and comprising a holding and guiding part, a spring and an axially movable cover is described in DE 41 19 192 A1. The cover is formed like a cup and extends over the spring and the holding and guiding part.

An arrangement comprising a cup-shaped feeder and a mandrel is described in DE 195 03 456 C1. The mandrel is fastened on a casting pattern. The feeder is mounted on the mandrel in such a way that a distance is maintained between its lower end and the surface of the casting pattern. A first and a second rigidly preset stop are preset on the mandrel for a first and a second distance-maintaining position. The feeder assumes the second distance-maintaining position, near the surface of the casting pattern, during the compaction of the molding sand, by a predetermined breaking point in the bottom of the feeder being made to open by the counter pressure emanating from the mandrel, allowing the feeder to go over into the second distance-maintaining position.

Before the feeder inserts are inserted, the expansion mandrels must first be fastened on the pattern plate, which is a laborious procedure. Furthermore, with an expansion mandrel, a precisely arranged knock-off edge can only be realized with difficulty. This knock-off edge is provided to make it possible for the residual feeder, i.e. the metal remaining in the feeder insert after casting, to be separated from the casting. The cleaning effort is therefore generally quite high. Expansion mandrels are also quite expensive and susceptible to wear.

The invention was therefore based on the object of providing a feeder insert which can withstand the forces occurring during the compaction of the molding material. Furthermore, at least in a preferred embodiment of the feeder insert, it should be possible to provide a knock-off edge which makes it possible for the residual feeder to be precisely separated from the casting.

This object is achieved by a feeder insert with the features of patent claim 1. Advantageous embodiments are the subject of the dependent claims.

The feeder insert according to the invention comprises a feeder body, in which a feeder cavity is arranged. The feeder body may in fact be of any desired form and is formed in the customary way. The feeder body usually has an approximately tubular form. The feeder thereby has a height which is greater than its diameter. The feeder body may for example be cylindrically formed. However, it is also possible that the feeder body tapers for example toward the bottom side, so that a small standing surface of the feeder insert on the pattern plate is achieved. The feeder body has on its bottom side an opening through which the feeder cavity is in connection with the cavity of the casting mold. The feeder body may likewise be open on its top side. However, it may equally be closed on its top side. The feeder body consists of the materials that are customary for the production of feeders and may be formed in an insulating and/or exothermic manner. Appropriate materials are known to a person skilled in the art. According to the invention, an energy absorbing device is provided on the top side of the feeder body. The feeder insert is fitted directly on the surface of the pattern plate, so that in a preferred embodiment a breaking edge can be created at the lower termination of the feeder insert. An energy absorbing device, which absorbs the forces or energy acting on the feeder insert during the compaction of the molding material, is provided on the top side of the feeder insert. This avoids the feeder body being compressed by the forces acting during the compaction and thereby broken up. The feeder therefore does not require an expansion mandrel to absorb the forces acting during the compaction of the molding material. However, it may be advisable to provide a fixed mandrel for positioning and fixing the feeder insert according to the invention.

The energy absorbing device preferably covers at least the top side of the feeder body. In this way, forces which act in the direction of the pattern plate parallel to the longitudinal axis of the feeder body can be substantially absorbed or at least significantly reduced. Since the energy absorbing device covers the entire top side of the feeder body, shearing off of parts of the feeder body during the compaction of the molding material can also be prevented.

The energy absorbing device may be formed in various ways. For instance, according to a first embodiment, the energy absorbing device may comprise a deformation element. The irreversible deforming of the deformation element has the effect that the force which acts on the top side of the feeder body during the compaction of the molding material is absorbed and the energy introduced is destroyed, so that no damage to the feeder body can occur. The deformation element may be formed in various ways. In a very simple embodiment, the deformation element may for example be a plate which is produced from a suitable deformable material, for example a rigid foam. Such a rigid foam may be a polymer foam, such as for example a polystyrene foam, or else a foam of an inorganic material, for example a foamed glass. The deformation element may also consist of metal and have a form which makes it possible to absorb energy by deforming of the deformation element. For example, the deformation element may be formed in a way similar to a can, the side walls being folded like an accordion. The can is compressed during the pressing of the molding material, by the accordion structure being further pressed together. Other structures are also possible. For example, it is conceivable that the deformation element has a honeycomb structure which is compressed under the action of the forces acting during the compression molding.

According to another embodiment, the energy absorbing device is formed as an elastic element. For this purpose, the energy absorbing device may for example comprise a spring element which is compressed during the pressing of the molding material, in order in this way to absorb the forces acting on the feeder body. However, other elastic elements may also be used. For example, it is also possible to use a rubber ring or a rubber plate which absorbs energy introduced into the feeder body by elastic deformation.

The energy absorbing device may also comprise a friction element. The energy introduced into the energy absorbing device during the compression molding is then converted into heat by the friction between two appropriately formed surfaces and is destroyed.

The energy absorbing device may be formed in various ways. In a preferred embodiment, it comprises a plate-shaped element which is arranged substantially perpendicular to the longitudinal axis of the feeder and has an extent which corresponds at least to the cross section of the top side of the feeder body. In the simplest embodiment, the energy absorbing device is for example a plate, for example a plate which can be deformed in the direction of the longitudinal axis of the feeder and is placed on the top side of the feeder body. The plate-shaped element may, however, also be formed in such a way that it has the form of a cap. In this embodiment, the plate-shaped element comprises a skirt running along its periphery that preferably reaches over the edge running around the circumference of the top side of the feeder body, in the direction of the side face of the feeder body, in the case where the plate-shaped element is resting on the top side of the feeder body. This facilitates the fixing of the energy absorbing device on the top side of the feeder body. The top side and bottom side of the plate-shaped element may be formed as substantially parallel running surfaces. However, the plate-shaped element may also have for example a greater thickness in the middle of its surface than at the periphery, so that the energy absorbing device is given a roof-shaped form.

In a preferred embodiment, the plate-shaped element has at least one continuation and the feeder body has on the top side at least one receptacle in which the continuation is received. The continuation may be formed, for example, as a peripheral ring on the bottom side of the plate-shaped element, which is inserted in a groove formed on the top side of the feeder body in the form of a peripheral circle. This allows the plate-shaped element to be fixed for example in a position such that it is not displaced during the introduction of the molding material and the subsequent compaction.

However, the continuation is formed with preference as a rod-shaped plug element and the receptacle is formed with preference as a sleeve. With preference, at least two rod-shaped plug elements, but with particular preference three or four or more plug elements, are provided on the side of the plate-shaped element that is facing the feeder body. The length of the plug elements may be chosen to be very short if the plugs merely serve for fixing the position of the energy absorbing device. However, the rod-shaped plug elements are used with preference in cooperation with the sleeves introduced into the feeder body for absorbing and destroying the energy which is introduced into the feeder body during the compression molding. The sleeves may be produced as a separate component which is produced for example from plastic or metal and introduced into the feeder body. However, it is also possible to form the feeder body directly in such a way that corresponding depressions on the top side are formed directly in the material of the feeder body.

As already explained, the rod-shaped plug elements may be used in cooperation with the sleeves for absorbing and destroying energy which would otherwise bring about a compression of the feeder body, which may lead to the breaking up of the feeder body.

In a first embodiment, arranged for this purpose along the wall of the sleeve are projections by which the diameter of the sleeve is reduced to the extent that it becomes slightly smaller than the diameter of the rod-shaped plug element. The projections may be formed for example as ridges which run in the direction of the longitudinal axis of the feeder body along the wall of the sleeve. If the rod-shaped plug elements of the plate-shaped element are inserted into the sleeve, the plate-shaped element is initially kept at a specific distance from the top side of the feeder body. If molding material is then introduced around the feeder insert and subsequently compacted, the plate-shaped element is moved in the direction of the longitudinal axis of the feeder body toward the top side of the feeder body. The rod-shaped plug elements thereby deform the projections arranged along the wall of the sleeve, so that energy which would otherwise lead to compression of the feeder body is absorbed on the one hand by the deformation and on the other hand by the friction between the sleeve and the rod-shaped plug element.

According to another embodiment, a spring element which produces a counterforce when the rod-shaped plug element penetrates the sleeve may also be provided in the sleeve. Energy which could otherwise bring about a compression of the feeder body is once again absorbed by the pressing together of the spring element. The spring element may also be formed in such a way that it presses against the side faces of the rod-shaped plug element and thereby brings about a high degree of friction between the spring element and the rod-shaped plug element.

In a preferred embodiment, the energy absorbing device has a skirt which reaches around the circumference of the feeder body and has in a direction perpendicular to the bottom side of the plate-shaped element an extent which corresponds at least to the length of the rod-shaped plug elements. In this way, grains of molding material are prevented from penetrating into a spacing between the top side of the feeder body and the bottom side of the energy absorbing device during the introduction of the molding material and falling from there for example into the feeder cavity.

According to a further preferred embodiment, a constriction is provided on or near the bottom side of the feeder body to form a breaking edge. Since the feeder insert according to the invention can be placed directly on the pattern plate, the position of the constriction in relation to the surface of the casting is defined, so that a breaking edge for the knocking off of the residual feeder can be arranged at a specific position. As a result, the effort required for cleaning the surface of the casting after the residual feeder has been knocked off is significantly reduced.

The invention is explained in more detail below with reference to an accompanying drawing. The same items are provided with the same designations. In the figures specifically:

FIG. 1 shows a cross section through a feeder insert according to the invention before compaction;

FIG. 2 shows a cross section through the feeder insert represented in FIG. 1 after compaction;

FIG. 3 shows a longitudinal section through a further embodiment of the feeder insert according to the invention before compaction;

FIG. 4 shows a longitudinal section and a cross section through a sleeve introduced into the top side of the feeder body; and

FIG. 5 shows a longitudinal section through a second embodiment of a sleeve introduced into the top side of the feeder body.

FIG. 1 shows a longitudinal section through a first embodiment of the shield feeder or plug feeder according to the invention along a longitudinal axis 13 of the feeder. The feeder insert comprises a feeder body 1, which encloses a feeder cavity 2. Provided toward the bottom side of the feeder body is an insert 3, by which a constriction can be formed to form a breaking edge. The insert 3 consists for example of steel sheet, wood or similar material. The feeder cavity 2 ends in an outlet opening 4, via which the feeder cavity 2 is in connection with the cavity of the casting mold. For the production of the casting mold, a pattern plate 5 takes the place of the cavity of the casting mold. Led through the outlet opening 4 is a mandrel 6, which is fastened on the pattern plate 5 and by which the feeder body 1 is fixed in its position. On the top side 7 of the feeder body 1, two depressions 8 in the form of a sleeve are introduced into the feeder body 1. The sleeve may be produced from metal, wood, plastic or similar materials and be inserted in corresponding depressions in the feeder body 1. However, the sleeve may also be formed directly in the material of the feeder body. Inserted respectively in the depressions 8 are rod-shaped plugs 9, which carry a plate-shaped element 10. The diameter of the plugs corresponds approximately to the diameter of the depressions 8. Devices which prevent the rod-shaped plugs 9 from penetrating completely into the depressions 8 are provided in the depressions 8. As a result, the plate-shaped element 10 is kept at a specific distance from the top side 7 of the feeder body 1. Provided along the outer circumference of the plate-shaped element 10 is a skirt 11, which is chosen to be of such a size that no molding material can penetrate into the intermediate space between the plate-shaped element 10 and the top side 7 of the feeder body 1 during the introduction of molding material. As a result, the plate-shaped element 10 comprises a shield- or boss-like form. The plate-shaped element 10 and the skirt 11 consist for example of steel sheet, wood, plastic or similar materials. Since the feeder insert is fixed on the pattern plate 5, molding material 12 is arranged around the feeder insert and compacted. The forces acting during the compaction have the effect that the plate-shaped element 10 is displaced in the direction of the longitudinal axis 13 of the feeder toward the top side 7 of the feeder body 1. As a result, the rod-shaped plugs 9 penetrate into the depressions 8. Interactions between the rod-shaped plug 9 and the sleeve 8 have the effect that energy is destroyed, for example by friction or deformation, and so prevent the feeder body 1 from being compressed. In the case of the embodiment represented in FIG. 2, after compaction the plate-shaped element 10 rests on the top side 7 of the feeder body 1. The feeder insert is surrounded on all sides by compacted molding material 12. Subsequently, the mandrel 6 and the pattern plate 5 are also removed, so that the casting mold is obtained. Arranged at the transition between the feeder cavity 2 and the cavity of the casting mold is a constriction 14, which after casting serves as a breaking edge for knocking off a residual part of the feeder.

In FIG. 3, a further embodiment of the feeder insert according to the invention is represented in longitudinal section. In the case of this embodiment, apart from the outlet opening 4 arranged on the bottom side, the feeder body 1 has an opening 15 in the top side of the feeder body 1. The embodiment represented in FIG. 3 is therefore formed as an open shield feeder or plug feeder. As in the case of the embodiment represented in FIGS. 1 and 2, depressions 8 are introduced into the top side 7 of the feeder body 1. The rod-shaped plugs 9 of the plate-shaped element 10 are inserted in these depressions. Molding material is then introduced around the feeder insert, as explained with respect to FIGS. 1 and 2, and this material is subsequently compacted. In this case, the plate-shaped element 10 is moved in the direction of the longitudinal axis 13 of the feeder toward the top side 7 of the feeder body 1. By interaction between the rod-shaped plug 9 and the depression 8, the force acting on the feeder body 1 in the direction of the longitudinal axis 13 of the feeder during the compaction of the molding material is absorbed and the energy is consumed, so that no compression of the feeder body 1 takes place and significantly higher forces can be used for the compression molding.

FIG. 4 shows a preferred embodiment of the depressions 8. Starting from the top side 7 of the feeder body, a depression 8 is introduced into the feeder body 1. FIG. 4b shows a longitudinal section through the depression 8 along a longitudinal axis 16. Arranged along the wall of the depression 8 are ridges 17, by which the cross section of the depression 8 is constricted. The ridges 17 run parallel to the longitudinal axis 16, the thickness of the ridges, i.e. their extent into the interior space of the depression 8, increasing as they become increasingly further away from the surface 7. In FIG. 4a, a cross section along the line a-a, shown in FIG. 4b, is represented.

It can be seen that a number of ridges 17 are arranged on the outer wall of the depression 8, whereby the cross section of the depression 8 is constricted. If a rod-shaped plug 9 (not shown) is then inserted into the depression 8, it can initially be pushed into the depression 8 only to a certain depth. When pushed in further, a frictional force is produced between the ridges 17 and the wall of the rod-shaped plug 9. In this case, the ridges 17 may also be deformed. When this happens, energy is consumed, so that the force exerted on the plate-shaped element by the compaction of the molding material is absorbed and the energy introduced can be destroyed. The embodiment of the depression 8 represented in FIG. 4 can be obtained by the appropriate structure being formed directly in the material of the feeder body 1. However, it is also possible to produce an appropriate sleeve, which is then inserted into a corresponding depression in the feeder body 1.

In FIG. 5, a further embodiment of the depression 8 is represented as a longitudinal section. Inserted in the depression 8 is a sleeve 18, the wall of which runs along the wall of the depression 8. The sleeve 18 may also have a collar 19, which rests on the top side 7 of the feeder body 1. Spring elements are arranged in the sleeve 18. These may be constructed for example from spring steel or plastic. The spring elements 20 can be moved with their one end in the direction of the wall of the sleeve 18, which is represented by the arrow 21. If a rod-shaped plug element 9 (not shown) is then inserted into the interior space of the sleeve 18, it initially comes to bear against the spring elements 20. If pressure is then exerted on the rod-shaped plug elements 9 in the direction of the longitudinal axis 16, the spring elements 20 are pivoted at their lower termination in the direction of the wall of the sleeve 18. They thereby oppose the movement of the rod-shaped plug elements with a counterforce, whereby the force exerted on the plate-shaped element 10 (not shown) is absorbed and the energy introduced is destroyed. The sleeve 18 may be produced from any suitable material. Suitable materials are, for example, steel or plastic.

Claims

1. A feeder insert for inserting into a casting mold used for casting metals, comprising a feeder body, which extends along a longitudinal axis of the feeder insert and comprises a feeder cavity, a bottom side in communication with the casting mold, and a top side that is situated opposite the bottom side, and an energy absorbing device provided on the top side of the feeder body.

2. The feeder insert as claimed in claim 1, characterized in that the energy absorbing device covers at least the top side of the feeder body.

3. The feeder insert as claimed in claim 1, characterized in that the energy absorbing device comprises a deformation element.

4. The feeder insert as claimed in claim 1, characterized in that the energy absorbing device comprises an elastic element.

5. The feeder insert as claimed in claim 1, characterized in that the energy absorbing device comprises a friction element.

6. The feeder insert as claimed in claim 1, characterized in that the energy absorbing device comprises a plate-shaped element which is arranged generally perpendicular to the longitudinal axis of the feeder insert.

7. The feeder insert as claimed in claim 6, characterized in that the plate-shaped element has at least one continuation element and the feeder body has at least one depression extending inward from the top side of the feeder body into which the continuation element is received.

8. The feeder insert as claimed in claim 7, characterized in that the continuation element comprises a rod-shaped plug element and the depression comprises a sleeve.

9. The feeder insert as claimed in claim 8, wherein ridges are that arranged along a wall of the sleeve such that their diameter within the sleeve decreases as they extend into the feeder body from the topside of the feeder body.

10. The feeder insert as claimed in claim 8, wherein the sleeve further comprises a spring element which produces a counterforce when the rod-shaped plug element is inserted into the sleeve.

11. The feeder insert as claimed in claim 1, characterized in that the energy absorbing device further comprises a skirt (11) which reaches around the upper circumference of the feeder body.

12. The feeder insert as claimed in claim 1, wherein the feeder body further comprises a constriction on or near the bottom side of the feeder body to form a breaking edge.

13. The feeder insert of claim 6 wherein the plate shaped element extends outward at least to a maximum cross section of the feeder body.

14. The feeder insert of claim 9 wherein a diameter of the plug element is smaller than the diameter of the sleeve.

15. A feeder insert for inserting into a casting mold used for casting metal comprising a feeder body which comprises a feeder cavity, a bottom side, a top side and an energy absorbing device introduced into one or more sleeves in the top side of the feeder body.

16. The feeder insert as claimed in claim 15, characterized in that the energy absorbing device comprises a deformation element.

17. The feeder insert as claimed in claim 15 characterized in that the energy absorbing device comprises an elastic element.

18. The feeder insert as claimed in claim 15, characterized in that the energy absorbing device comprises a friction element.

19. The feeder insert as claimed in claim 15, wherein the sleeve further comprises a spring element which produces a counterforce when the energy absorbing device is inserted into the sleeve.

20. The feeder insert as claimed in claim 15, wherein the feeder body further comprises a constriction on or near the bottom side of the feeder body which forms a breaking edge.