EP1184104B1 - Feeder insert - Google Patents

Abstract

Feeder insert (2) used for casting metals comprises at least two mold elements (4, 6) which slide into each other along a longitudinal axis (20) to surround a hollow space for liquid metal. Independent claims are also included for: (a) a kit for manufacturing a feeder insert; and (b) a method for arranging a feeder insert in a casting mold.

Description

The present invention primarily relates to a closed one Feeder insert, hereafter also called feeder for use in Pouring of metals in molds, with the features according to the preamble of claim 1, so as known from US-A-5,462,106.

Such feeder inserts are used in the manufacture of a casting mold integrated into these and form a space surrounded by molding material, the has a passage (passage) to the mold cavity and during casting is filled by the casting flow with liquid metal, which during the Freezing process flow back to the casting and the volume deficit at to compensate for the solidification of the casting. In this way, the Formation of so-called voids (which are shrinkage cavities, which are caused by the Metal volume contraction during the solidification process arise) prevented.

To ensure proper feeding, this must be done later in the feeder metal solidify as the metal of the casting, i.e. the module (volume to surface ratio) of the feeder must be larger than that of the casting. At the same time, after the solidification for cost reasons, the smallest possible residual amount of metal in the feeder remain, and for this purpose the walls of the feeder become common from an exothermic material, such as an aluminothermic Mixture, formed. Such a material is through the liquid metal ignited, and it therefore runs after the penetration of the casting flow in such a feeder an exothermic reaction by which in the feeder interior metal is supplied heat. This remains through the Heat supply longer liquid than the metal in the mold cavity of the mold and is thus better usable for the power supply.

Many molds are made using a model plate, which defines the inner contour of the mold cavity. In the places where a feeder insert is required, then is often a holding device intended for the feeder insert, e.g. a thorn for fixing the Position of the feeder insert.

After placing the feeders on the model plate (with or without Dorn) becomes then the molding material (usually molding sand, in individual cases also other granular materials) applied to the model plate so that he Wrapped in the feeder insert. In a further step, the molding material is then compacted and the feeder thereby more or less firmly from the compacted Molded material included. One speaks in this respect also of compression molding.

In the endeavor, a punctual density feed even of small casting sections To achieve the Stell- or essay areas are modern Feeder inserts often designed very small. The feeder insert tapers Thus, considerably in the direction of its essay area, and the Applying the molding material on the mold plate often occurs the consequence problem on that the compaction of the molding material in the environment of the feeder neck near the top surface is insufficient, which is disadvantageous during casting is.

Another problem is that in particular exothermic but also insulating feeders with the process of molding material compaction associated compression forces often can not withstand and therefore break. Such a break inevitably leads to one uncontrolled feeding of the casting.

Despite this long-known problem, the trend is always on higher compression pressures, what the manufacturers of feeder inserts already forced to, especially stable, thick-walled feeder inserts However, due to the increased material requirements right are expensive.

For some years it is tried, with the increase of the compaction pressure linked problems using so-called spring pins to encounter. Spring pins are as well as fixed (rigid) mandrels intended to keep a feeder insert in a predetermined position. she usually comprise (a) a tubular element for attachment to a model plate, (b) one disposed in the tubular member Spring and (c) a spring resting on the spring, longitudinally within the tubular element telescopically displaceable spike tip element. Such a spring mandrel is usually on the model plate (model surface) attached, and then a feeder insert is placed on it, whose lower surface is in the starting arrangement before filling the Formstoffs located at a predetermined distance from the model surface. During the subsequent filling of the molding material, this therefore also runs between model surface and feeder (lower surface). And thus, there is the subsequent compression (compression molding) no direct contact between feeder and model surface, causing a destruction of the feeder Even with application of high compression pressures is usually prevented. On the mounted on the spring mandrel feeder insert acts during compression molding a force in the direction of the model plate, which causes that the feeder insert against the action of the spring force towards the Model plate is pressed. In the gap between feeder insert and Model plate located molding material layer is compressed.

Although the use of spring thorns to alleviate the above contributed, but in turn brings a number of others Problems with yourself.

Thus, the separation of the so-called residual feeder (i.e. the casting remaining in the feeder insert, solidified metal) from the casting often not directly at the breaking point, i. the mental Interface between casting and feeder, but in a considerable Distance from the casting, somewhere in the range of often several centimeters wide sand gap between casting and feeder insert.

A sensible use of refractive cores (also as constricting, knock-down or collar cores), in the field of foundry technology otherwise used to provide a precise localized separation of To reach residual feeder and casting was when using spring thorns not possible yet. The cleaning effort is therefore usually quite high. Spring pins are also quite expensive and susceptible to wear.

In view of the problems outlined above, it was the primary one Object of the present invention to provide a feeder insert in the Foundry operation withstands high compression pressures.

The footprint of the specified feeder should be included preferably be dimensioned small without relevant stability disadvantages can.

In addition, the use of expensive and susceptible to wear Spring pins, at least as a rule dispensable.

Finally, the feeder insert should also be put together can be used with a breaker core, the separation of the residual feeder facilitated by the casting. Such a breaker core is doing in Frame of the present text as part of the feeder insert understood and not as a separate component.

The task is solved by specifying a closed Feeder insert of the type mentioned with the further features according to characterizing Part of claim 1.

The displaceability of the first and second form element into one another causes the during a conventional compression process in the feeder longitudinal direction acting on the feeder insert according to the invention high Compression pressures (compression forces) do not lead to its destruction, but only tolerated by the compressibility of the surrounding molding material (molding sand) limited insertion of the one element element in the other one. The footprint of the feeder insert can small and the Speiserwandung be comparatively thin.

The form elements should be out of their original configuration, i. out the relative arrangement, which is for the mold elements before wrapping the Feeder insert is provided with molding material, at least 5 mm, preferably can be pushed together by 10 mm.

The feeder insert can meet the requirements of the individual case corresponding, for example, in the manner of a compact or ball feeder designed or with a nearly cylindrical top in the upper riser be provided.

When using a feeder insert according to the invention it will only be exceptionally advantageous to use a spring thorn, because its effect described above essentially corresponds to that by the reached feeder insert according to the invention.

The use of spring mandrels with the feeder inserts according to the invention is therefore not excluded, but usually can but on it be waived.

The use of a fixed centering mandrel, however, is in many Cases useful. A preferred feeder insert according to the invention is therefore in particular, for use with a centering mandrel can be designed as a self-centering feeder. Such a self-centering Feiser has one or more wall sections that towards the top in operation (opposite the feeder passage) Rejuvenate the end wall of the feeder so that a spike tip when positioning the feeder insert along these sections into theirs Target position is guided. In the (upper) wall part, which the The feeder passage is opposite, then often a centering provided for receiving the mandrel tip, cf. our DE utility model 93 03 392. A self-centering feeder according to the invention especially suitable for use on fast molding equipment.

First and second form element of a feeder insert according to the invention can be glued together after production or otherwise get connected. The form elements can also be used as separate parts stored and combined (stacked) as needed. Identical first (or second) form elements can be with style (e.g., in size) different second (or first) features be combined to respective feeder inserts according to the invention.

• über die das erste Formelement (in der Ausgangsanordnung) das zweite Formelement trägt und
• die so abtrennbar oder deformierbar sind, daß ein ineinander Verschieben der zwei Formelemente (aus der Ausgangsanordnung heraus) entlang der Speiser-Längsachse möglich ist.

Particularly preferred are feeder inserts according to the invention, in which one or more holding elements are arranged on the first and / or second form element,

• via which the first mold element (in the starting arrangement) carries the second mold element and
• which are so separable or deformable that a telescoping of the two form elements (out of the output assembly) along the feeder longitudinal axis is possible.

The holding elements are preferably an integral part of respective formula elements, and they can be used in the manufacture of each Moldings without additional step to be molded to this. It can in particular with them stand or clamping projections, circumferential Stand rings, engageable with complementary recesses pins or the like. It is important in each case that the holding elements are designed so that they in the foundry, if first and second Form element still present approximately in their initial arrangement, the molding material but already filled in the molding box, by the subsequent Molding material compaction process of its associated form element can be separated or at least so far deformed that first and telescoping second mold element. The retaining elements are therefore preferably only over small connecting surfaces with their associated Form element connected.

As an alternative to the use of retaining elements is the use of a Spring mandrel. Such a can namely a second, in operation upper Shaping element in the intended starting position relative to the model surface and hold the first mold element without the invention Feeder insert itself includes holding elements. But spring thorns like mentioned in the beginning are quite expensive and susceptible to wear, is their use limited to exceptional cases.

Preferably, this is closer to the passage of the feeder sleeve or this forming first mold element designed so that it (optionally after separation or deformation of holding elements) in the second mold element can be inserted. The outside dimensions of the first, in Operation lower, the casting closer molding element are therefore preferred smaller than the inner dimensions of the associated second, in operation upper Form element. This embodiment is compared with the reverse one (Also inventive) embodiment in which the upper in operation Form element in the lower mold element can be inserted, advantageous because it ensures that during the filling process no disturbing quantities Mold material penetrate into the first mold element.

Particularly advantageous is an embodiment in which the first, im Operation lower mold element is designed so that it (telescopically) in the second mold element can be inserted, wherein the outer wall of the first element form fit into the inner wall of the second element element intervenes. The gap width between the outer wall of the first Formulas and the inner wall of the second formula element is in the intended output arrangement of the mold elements, if necessary is characterized by the position of the holding elements, preferably maximum 3 mm, advantageously not more than 1.5 mm. In this embodiment can during the molding material filling no relevant molding material quantities penetrate into the gap between the mold elements, so that their relative displacement at least not significantly affected becomes.

The mold elements should be made of their intended, if necessary by the holding elements defined output arrangement out in the feeder longitudinal direction by at least 5 mm, preferably by at least 10 mm into each other let it before, due to the further nesting forces occurring between the form elements to break or Breaking of the first or second formula element comes.

It is particularly favorable if the first and / or the second form element includes one or more guide elements that are arranged a tilting or tilting of the two form elements relative to each other at least substantially prevent, if this (from the starting arrangement out) along the feeder longitudinal axis into each other become. These guide elements preferably have the shape in Feeder longitudinally extending thin strips or beads, and she are advantageously located on the outer wall of that element, which can be inserted into the partner mold element; in In a large number of cases they are on the outside of the first one Formula elements arranged.

Advantageously, in the first mold element of an inventive Feeder insert integrated a breaking edge, if necessary Part of a breaker core, which is then in operation directly on the model plate can be put on. This integration of a breaking edge (of a refractive core) ensures a significant reduction in the foundry business Putzaufwands in comparison with the known feeder inserts, the Use with spring thorns are provided and therefore no breaking edge (no breaker core) own. The footprint of the feeder according to the invention especially when using a crushing edge (a refractive core) very kept small.

The feeder insert according to the invention or the associated form elements may be partially or completely made of insulating or exothermic molding compounds be prepared. If a breaker core is integrated into the first shaping element, so this is typically not exothermic, the associated second Form element will then often be exothermic.

The feeder inserts according to the invention comprise two or more Shaped elements that are combined according to demand when stored separately can. The invention therefore also relates to a kit for manufacturing a feeder insert according to the invention, comprising a first mold element and a second mold member which can be arranged to be along a feeder longitudinal axis are slidable. preferred Embodiments of belonging to the kit form elements are the above to remove the feeder insert according to the invention.

• Bereitstellen eines erfindungsgemäßen Speisereinsatzes in einer seiner vorstehend beschriebenen Ausgestaltungen,
• Anordnen des Speisereinsatzes in einer Formmaschine (dem Raum über einer Modellplatte, der in der Regel von einem aufgesetzten Formkasten umgrenzt wird)
  so daß das erste und das zweite Formelement eine (Ausgangs-)Anordnung einnehmen, aus der heraus die zwei Formelemente entlang einer Speiser-Längsachse ineinander verschiebbar sind,
• Einfüllen von Formstoff in die Formmaschine (den auf die Modellplatte aufgesetzten Formkasten), so daß die Außenwandungen des Speisereinsatzes mit dem Formmaterial kontaktiert sind,
• Verdichten des Formstoffs (Formpressung), so daß das erste und das zweite Formelement (gegebenenfalls nach Abtrennung oder Deformierung von Halteelementen) entlang der Speiser-Längsachse ineinander verschoben werden.

According to a further aspect, the invention relates to a method for arranging a feeder insert in a casting mold, comprising the following steps:

• Providing a feeder insert according to the invention in one of its embodiments described above,
• Arranging the feeder insert in a molding machine (the space above a model plate, which is usually bounded by an attached molding box)
  so that the first and the second mold element occupy an (initial) arrangement, from which the two mold elements can be slid into one another along a longitudinal axis of the feeder,
• Filling molding material into the molding machine (the molding box placed on the model plate), so that the outer walls of the feeder insert are in contact with the molding material,
• Compressing the molding material (compression molding), so that the first and the second mold element (optionally after separation or deformation of holding elements) along the feeder longitudinal axis are shifted into one another.

The molding machine comprises in the usual way a model plate (i.e., a patterning machine for molding machines, usually consisting of a flat plate with cast-in or mechanically fastened models), and the first mold member is preferably arranged to project the compression process in direct contact with the model plate (the Model surface) stands. This is especially true when in the first Form element is integrated a breaker core.

With regard to further preferred embodiments of the invention Method is preferred to the above explanations Referenced feeder inserts.

Fig. 1a

Längsschnitt durch einen erfindungsgemäßen Speisereinsatz in seiner Ausgangsanordnung, mit zwei ineinander verschiebbaren Formelementen, wobei der Speisereinsatz mittels eines Zentrierdorns auf einer Modellplatte befestigt ist,

Fig. 1b

Länsgsschnitt durch das untere (erste) Formelement des Speisereinsatzes gemäß Fig. 1a,

Fig. 1c

Draufsicht auf das untere (erste) Formelement des Speisereinsatzes gemäß Fig. 1a,

Fig. 2

Längsschnitt durch einen alternativen Speisereinsatz mit eingeformter Brechkante

Fig. 3a - d

Schematische Darstellung eines erfindungsgemäßen Verfahrens zur Anordnung eines erfindungsgemäßen Speisereinsatzes in einer Gießform.

Hereinafter, preferred embodiments of the invention will be explained in more detail with reference to the accompanying figures. They show:

Fig. 1a

Longitudinal section through a feeder insert according to the invention in its starting arrangement, with two form elements which can be displaced into one another, wherein the feeder insert is fastened on a model plate by means of a centering mandrel,

Fig. 1b

Länsgsschnitt through the lower (first) mold element of the feeder insert of FIG. 1a,

Fig. 1c

Top view of the lower (first) mold element of the feeder insert according to Fig. 1a,

Fig. 2

Longitudinal section through an alternative feeder insert with molded breaking edge

Fig. 3a - d

Schematic representation of a method according to the invention for the arrangement of a feeder insert according to the invention in a casting mold.

The in Fig. 1a in its output arrangement (before filling Molding material and prior to the compaction process) according to the invention Feeder insert 2 comprises a first (lower) mold element 4 and a second (Upper) mold element 6, wherein both mold elements are substantially rotationally symmetrical are formed. The longitudinal axis of rotation of the feeder insert 2 (feeder longitudinal axis) is indicated by a dashed line Line 20 marked.

The first mold element 4 is shown separately in Fig. 1b again Longitudinal section and shown in Fig. 1b in plan view. It is off a molding compound (e.g., insulating or exothermic) shaped and relative thin-walled. The footprint of the first element element 4, with the this is seated on a model plate 22 is small, the footprint diameter is only about 40 mm, the diameter of the inside of the footprint lying feeder passage only about 20 mm. Starting from his Footprint expands the first form element outside to a maximum Diameter of about 77 mm conical, and the thus defined conical Section 34 then merges into an upper section 44 which follows at the top very slightly conical up to a diameter of about 76 mm rejuvenated.

Already in the area of the upper section 44, but the lower conical Section 34 adjacent to the first mold element 4 are four in total Holding projections 12 integrally formed. The (imagined) interfaces between Holding projections 12 and mold element 4 are each quite small, so that the Holding projections 12 with little effort mechanically from the mold element can be separated.

The holding projections 12 are also assigned a total of four Guide and spacer strips 14 extending from the retaining projections extend in the longitudinal direction of the feeder sleeve 2 upwards and opposite the outer wall of the upper portion 44 of the lower mold element 4 each project by about 2 mm.

According to Fig. 1a with its lower edge 26 on the retaining projections 12th of the lower mold element 4 is placed on the second (upper) mold element 6. It is formed from an exothermic molding compound and also very thin-walled educated. The outer contour of the upper mold element 6 tapers towards the top slightly towards one on the outside substantially flat upper wall termination 36. The inner wall of the upper Formulas 4 runs, starting from the lower edge 26 first parallel to the outer wall of the upper portion 44 of the lower mold element 4 and then goes into a conically upwardly tapering wall section 46 above, along which the top of a centering pin at Positioning of the feeder insert can be performed. The conical Wandungsabschnitt 46 finally opens into a in the feeder axis lying, passing through the termination 36 Zentrierausnehmung 56 for Picking up a thorn top.

The two form elements 4, 6 are designed so that the four Guide rails 14 of the lower mold element 4 frictionally engaged on the inner wall of the upper die element 6, if this, as in Fig. 1a shown in the output arrangement on the four retaining projections of the lower element 4 rests. They therefore cause a press fit and prevent an undesired lateral displacement of the two form elements; they also define a uniform width of the gap between the lower (here inner) and the upper (here outer) form element.

In Fig. 1a, finally, a centering pin 16 is located, which is attached to the model plate 22 and from there (always in the feeder rotational axis 20) through the feeder passage 10 and the feeder cavity through into the Zentrierausnehmung 56 inside extends.

The two form elements 4, 6 of the feeder insert 2 can be telescopically push together when parallel to the axis of rotation 20 a directed onto the pattern plate 22 force (arrow F) on the feeder insert acts, as for example after the filling of molding material Forming is the case (see Fig. 3a-d). The force only has to be sufficiently large to the retaining projections 12 from the lower mold element. 4 separate.

The inner wall of the second (upper, outer) element element approaches when pushed onto the first (lower, inner) form element of the Outside wall continuously and finally passes, after a displacement path of about 15 mm, all around in contact with it. Such a displacement path is enough for many compaction processes. The final position of the lower edge 26 of the upper mold element 6 after covering said Displacement path is indicated by a dashed line. The Guide rails 14 are when nesting the mold elements 4.6 deformed or severed and / or they cut into the inner wall of the outer (upper) element element 6.

The centering recess 56 extends through the upper end wall of the feeder sleeve 2 and the tip of the centering mandrel comprises a cylindrical portion which is significantly longer than 15 mm and its diameter to the inner diameter of the Zentrierausnehmung 56th is adapted. This is why it comes with the telescopic sliding of the upper on the lower mold element not to a handicap; the spike tip occurs rather unimpeded out of the feeder insert.

The lower edge 26 of the lower mold element 4 projecting wall of the upper die element 6 acts like a during a compression process Stamp surface on the molded material to be compressed between edge 26 and Model plate 22. The (also) using a compaction process The processes occurring in the feeder insert 2 are described below with reference to FIG. 3a-d explained in more detail.

FIG. 2 shows an alternative feeder insert 202 according to the invention shown in longitudinal section. In contrast to the feeder insert 2 from the Fig. 1a-c comprises the first (lower) mold element 204 of the feeder sleeve 202 a crushing edge 214. The feeder sleeve 202 is also more compact and Thick walled trained as the feeder 2. The existing here Centering recess 256 does not pass through the upper end of the riser, but extends in the longitudinal direction of the feeder insert so far that an associated centering mandrel inserted sufficiently far into it can be when the upper mold member 206 telescopically on the lower Form element 204 is moved in the direction of the model plate.

In Figs. 3a-d is a method according to the invention for the arrangement a feeder insert according to the invention in a casting mold schematically shown. The following explanations apply to the feeder insert 1a-c as well as for the feeder sleeve of FIG. 2.

According to Fig. 3a, a first mold element 104 is on a centering mandrel 116 mounted, which is mounted on a pattern plate 122. The form element 104 is in direct contact with the model plate 122 brought.

Subsequently, as shown in FIG. 3b, a second mold element 106 on the first mold element 104 placed so that it is supported by this. To For example, retaining projections 112 are provided which in their shape and function explained with reference to FIGS. 1a-c retaining projections 12th correspond. There is now a composite feeder sleeve 102 in FIG its initial arrangement, cf. Fig. 1a.

In a subsequent step shown in Fig. 3c, the feeder sleeve 102 coated with molding sand 150 or another molding material (sheath indicated only in the lower area).

After a compression process not shown results the arrangement of FIG. 3d. The retaining projections 112 are from the first Shaped element 104, the second (upper) mold element 106 is telescopically a little way on the first (lower) mold element 104th postponed. The displacement path D of the second feature 106 on the fixed in its position first mold element 104 is thereby by the measure the molding material compression predetermined and limited.

As the first mold element 104 overhanging outer wall of the second die element 106 on the between them and the model plate 122nd During the compaction process acts like a stamp, it comes in this Area for an excellent molding compaction (in Fig. 3d by a in comparison with Fig. 3c denser puncturing of the molding sand 150 indicated).

Claims (9)

1. Feeder insert for use when casting metals in casting moulds, comprising a cavity for receiving liquid metal, the feeder insert (2, 102, 202) including at least two mould elements (4, 104, 204; 6, 106, 206) which are displaceable one inside the other along a longitudinal feeder axis (20) and which laterally surround the cavity for receiving liquid metal, characterised in that one or more retaining elements (12, 112) is/are arranged on the first mould element (4, 104, 204) located closer to the through-passage of the feeder insert (2, 102, 202) or forming same, and/or on the second mould element (6, 106, 206),

   by means of which retaining elements (12, 112) the first mould element (4, 104, 204) supports the second mould element (6, 106, 206), and

   which retaining elements (12, 112) can be separated or deformed in such a way as to make possible displacement of the two mould elements one into the other along the longitudinal feeder axis (20).
2. Feeder insert according to claim 1, characterised in that the first mould element (4, 104, 204) is so configured that it can be pushed into the second mould element (6, 106, 206).
3. Feeder insert according to claim 2, characterised in that the first mould element (4, 104, 204) is so configured that it can be pushed into the second mould element (6, 106, 206), the outer wall of the first mould element engaging with a form fit in the inner wall of the second mould element.
4. Feeder insert according to any one of the preceding claims, characterised in that the first and/or the second mould element includes one or more guide elements (14) which are arranged to at least substantially prevent skewing or tilting of the two mould elements (4, 104, 204; 6, 106, 206) relative to one another when they are pushed one into the other along the longitudinal feeder axis (20).
5. Feeder insert according to any one of the preceding claims, characterised in that a breaker edge (214) is integrated in the first mould element (4, 104, 204), as part of a breaker core, if applicable.
6. Feeder insert according to any one of the preceding claims, characterised in that a guide for a centring mandrel (16, 116) is integrated in the first and/or second mould element.
7. Kit for producing a feeder insert (2, 102, 202) according to any one of the preceding claims, comprising a first mould element (4, 104, 204) and a second mould element (6, 106, 206) which can be so arranged that they are displaceable one into the other along a longitudinal feeder axis (20).
8. Method for arranging a feeder insert in a casting mould, comprising the following steps:

   placing in readiness of a feeder insert (2, 102, 202) according to any one of claims 1 to 6;

   arranging of the feeder insert in a moulding machine
   so that the first and second mould elements (4, 104, 204; 6, 106, 206) are present in an arrangement from which the two mould elements are displaceable one into the other along a longitudinal feeder axis (20);

   pouring of moulding material into the moulding machine so that the outer walls of the feeder insert (2, 102, 202) are in contact with the moulding material;

   compression of the moulding sand so that the first and second mould elements are displaced one into the other along the longitudinal feeder axis (20).
9. Method according to claim 8, wherein the moulding machine includes a pattern plate (22, 122) and the first mould element (4, 104, 204) is inserted into the moulding machine in such a way that it is in direct contact with the pattern plate.

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