EP1184104A1 - 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 relates primarily to a closed one Feeder insert, also called feeder for short, for use with Pouring metals into molds, with a cavity for receiving liquid Metal.

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

In order to ensure a proper feeding process, the metal in the feeder solidifies later than the metal of the casting, i.e. the module (ratio of volume to surface) of the feeder must be larger than that of the casting. At the same time, after solidification For cost reasons, the smallest possible amount of metal in the feeder remain, and for this purpose the walls of the feeder become frequent made of an exothermic material, for example an aluminothermic Mixture, formed. Such a material is made by the liquid metal ignited, and therefore it runs in after the pouring flow such a feeder exotherms, resulting in the inside of the feeder existing metal heat is supplied. This remains through the Heat supply liquid longer than the metal in the mold cavity of the mold and is therefore better usable for feeding.

Many molds are made using a model plate, which specifies the inner contour of the mold cavity. In the places where a feeder insert is required, then is often a holding device intended for use in feeders, e.g. a thorn to fix the Location of the feeder insert.

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

In the endeavor to selectively feed even small areas of castings to achieve, the space or top areas are more modern Feeder inserts are often designed to be very small. The feeder insert tapers thus considerably towards its top surface, and at Applying the molding material to the molding plate often gives rise to the subsequent problem on that the compression of the molding material in the vicinity of the esophagus insufficiently close to the top surface, which is disadvantageous when casting is.

Another problem is that in particular exothermic insulating feeders also with the process of molding compression associated upsetting forces often cannot withstand and therefore break. Such a break will inevitably lead to one uncontrolled feeding of the casting.

Despite this problem, which has been known for a long time, the trend is forever higher compression pressures, what the manufacturers of feeder inserts has already forced particularly stable, thick-walled feeder inserts to offer, but due to the increased material requirements quite are expensive.

For some years now, attempts have been made to increase the compression pressure linked problems using so-called spring mandrels to encounter. Spring mandrels as well as fixed (rigid) mandrels are designed to to hold a feeder insert in a predetermined position. she typically include (a) a tubular member for attachment a model plate, (b) one arranged in the tubular element Spring and (c) a resting on the spring, in the longitudinal direction within the tubular element telescopically displaceable mandrel tip element. Such a spring mandrel is usually on the model plate (model surface) attached, and then a feeder insert is placed on it, the lower surface of which is in the starting arrangement before the filling of the Molding material is located at a predetermined distance from the model surface. The subsequent filling of the molding material therefore also runs between model surface and feeder (bottom surface). And so there is at the subsequent compression (compression molding) no direct contact between feeder and model surface, so that destruction of the feeder is usually prevented even when applying high compression pressures. During compression molding, the feeder insert placed on the spring mandrel acts a force in the direction of the model plate that causes the feeder insert against the action of the spring force in the direction of the Model plate is pressed. The in the gap between feeder insert and The molded material layer on the model plate is compressed.

The use of spring mandrels does alleviate the above problems described, but again brings a number of others Problems with themselves.

This is how the so-called residual feeder (i.e. the downstream) is separated solidified metal remaining in the feeder insert) from the casting often not directly at the predetermined breaking point, i.e. 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 the casting and feeder insert.

A sensible use of crushing cores (also as constricting, or collar cores) used in the field of foundry technology otherwise used to precisely localize separation from Reaching the remaining feeder and casting was done using spring mandrels so far not possible. The cleaning effort is therefore usually quite high. Spring mandrels are also quite expensive and prone to wear.

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

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

In addition, the use of expensive and prone to wear Spring mandrels are at least generally not necessary.

And finally, the feeder insert to be specified should also be together can be used with a crushing core that separates the residual feeder relieved by the casting. Such a crushing core is in the Framework of the present text as part of the use of food understood and not as a separate component.

The task is solved by specifying a closed one Feeder insert of the type mentioned, wherein the feeder insert at least two into one another along a longitudinal axis of the feeder (telescopic) comprises displaceable shaped elements which liquid the cavity for receiving Enclose metal on the side. A first shaped element is closer to Passage of the feeder insert arranged as an associated second Feature.

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

The shaped elements should be out of their initial arrangement, i.e. out the relative arrangement out for the molded elements before wrapping the Feeder insert with molding material is provided, at least by 5 mm, can preferably be pushed into each other by 10 mm.

The feeder insert can meet the requirements of the individual case correspondingly, for example, in the manner of a compact or ball feeder designed or with an almost cylindrical feeder cap in the upper area be provided.

When using a feeder insert according to the invention, it only becomes in exceptional cases it may be advantageous to use a spring mandrel, because the effect described above corresponds essentially to that of the reached feed 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 on it to be dispensed with.

However, the use of a fixed centering mandrel is common in many Cases make sense. A preferred feeder insert according to the invention is therefore set up for use with a centering mandrel, in particular can be designed as a self-centering feeder. Such a self-centering Speiser has one or more wall sections that towards the upper one in operation (opposite the feeder passage) Taper the end wall of the feeder so that a thorn tip when positioning the feeder insert in these along these sections Target position is performed. In the (upper) wall part, which the Opposing feeder passage is then often a centering recess intended to accommodate the mandrel tip, cf. our DE utility model 93 03 392. Is a self-centering feeder according to the invention especially suitable for use on fast molding lines.

First and second shaped element of a feeder insert according to the invention can be glued together or otherwise after their manufacture get connected. The shaped elements can also be used as separate parts stored and combined (stacked) as needed. Identical first (or second) form elements can also be constructed (e.g. in size) different second (or first) form elements can be combined into 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.

Feeder inserts according to the invention are particularly preferred in which one or more holding elements are arranged on the first and / or second shaped element,

• via which the first shaped element (in the starting arrangement) carries the second shaped element and
• which can be separated or deformed in such a way that the two shaped elements can be moved into one another (out of the starting arrangement) along the longitudinal axis of the feeder.

The holding elements are preferably an integral part of the respective formula element, and they can be used in the manufacture of each Form elements can be molded onto this without an additional step. It can with them in particular around standing or clamping projections, rotating Stand rings, pins that can be brought into engagement with complementary recesses or act like that. It is important that the holding elements are designed to operate in the foundry when the first and second The molding element is still roughly in its initial arrangement, the molding material but is already filled in the mold box by the subsequent one Molding material compression process from its associated shaped element can be separated or at least deformed to the extent that the first and can slide one another into each other. The holding elements are therefore preferably only via small connecting surfaces with their associated one Form element connected.

As an alternative to using holding elements, the use of a Spring mandrel. One such can namely be a second one, the upper one in operation Form element in the intended starting position relative to the model surface and hold to the first shaped element without the inventive Feeder insert itself includes holding elements. Since spring mandrels, however, like mentioned at the outset are quite expensive and prone to wear, their use be limited to exceptional cases.

This is preferably closer to the passage of the feeder insert this forming the first shaped element so that it (if necessary after separating or deforming holding elements) into the second shaped element can be inserted. The outer dimensions of the first, in Operation of lower form elements closer to the casting are therefore preferred smaller than the internal dimensions of the associated second, upper in operation Form element. This configuration is the reverse of that (Also according to the invention) embodiment in which the upper in operation Shaped element can be inserted into the lower shaped element, advantageous because it ensures that no disturbing quantities are present during the filling process Penetrate molding material into the first molding element.

An embodiment is particularly advantageous in which the first, in Operation lower mold element is designed so that it (telescopic) in the second shaped element can be inserted, the outer wall of the first form elements in the inner wall of the second form element intervenes. The gap width between the outer wall of the first Form elements and the inner wall of the second form element is in the intended starting arrangement of the shaped elements, which if necessary is characterized by the position of the holding elements, preferably maximum 3 mm, advantageously not more than 1.5 mm. With this configuration can not relevant quantities of molding material during the molding material filling penetrate into the gap between the shaped elements, so that at least not significantly impaired their relative displaceability becomes.

The shaped elements should come from their intended, if necessary output arrangement defined by the holding elements in the longitudinal direction of the feeder by at least 5 mm, preferably by at least 10 mm leave before pushing due to further nesting Forces occurring between the shaped elements to tear or Breaking of the first or second feature comes.

It is particularly favorable if the first and / or the second shaped element comprises one or more guide elements which are set up tilting or tilting of the two shaped elements relative to one another to prevent at least essentially when this (from the output arrangement out) shifted into each other along the longitudinal axis of the feeder become. These guide elements preferably have the shape themselves Thin strips or ridges extending along the length of the feeder, and them are advantageously located on the outer wall of that molded element, which can be inserted into the partner form element; in So in a lot of cases they are on the outside of the first Formula elements arranged.

Advantageously, the first molded element is an inventive one Feeder insert integrated a breaking edge, which if necessary Is part of a crushing core, which is then directly on the model plate during operation can be put on. This integration of a breaking edge (a breaking core) ensures a significant reduction in Cleaning effort in comparison with the known feeder inserts used for Use with spring mandrels are provided and therefore no breaking edge (no crusher core). The footprint of the feeder according to the invention can be very difficult, especially when using a crushing edge (a crushing core) be kept small.

The feeder insert according to the invention or the associated shaped elements can partially or completely from insulating or exothermic molding compounds be made. If a crushing core is integrated in the first shaped element, so this is typically not exothermic, the associated second The shaped element will then often be exothermic.

The feeder inserts according to the invention comprise two or more Form elements that can be combined as required when stored separately can. The invention therefore also relates to a kit for manufacturing of a feeder insert according to the invention, comprising a first shaped element and a second shaped element which can be arranged so that they can be moved into one another along a longitudinal axis of the feeder. preferred Embodiments of the form elements belonging to the kit are the above statements 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, with the following steps:

• Providing a feeder insert according to the invention in one of its configurations described above,
• Arranging the feeder insert in a molding machine (the space above a model plate, which is usually delimited by an attached molding box), so that the first and the second molding element assume an (initial) arrangement from which the two molding elements are arranged along a feeder Longitudinal axis are displaceable,
• Pouring 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,
• Compression of the molding material (compression molding) so that the first and the second molding element (if necessary after separating or deforming holding elements) are pushed into one another along the longitudinal axis of the feeder.

The molding machine usually includes a model plate (i.e. a model device for molding machines, usually consisting of a flat plate with cast-in or mechanically fastened models), and the first mold element is preferably arranged so that it is in front the compression process in direct contact with the model plate (the Model surface). This is especially true if in the first Forming element is integrated into a crushing core.

With regard to further preferred embodiments of the invention Process is preferred to the above explanations Referrer inserts referenced.

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.

Preferred embodiments of the invention are explained in more detail below with reference to the attached figures. They represent:

Fig. 1a

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

Fig. 1b

Longitudinal section through the lower (first) shaped element of the feeder insert according to FIG. 1a,

Fig. 1c

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

Fig. 2

Longitudinal section through an alternative feeder insert with a molded breaking edge

3a-d

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

The in its initial arrangement in Fig. 1a (before the filling of Molding material and shown before the compression process) according to the invention Feeder insert 2 comprises a first (lower) molded element 4 and a second (Upper) shaped element 6, both shaped elements being essentially rotationally symmetrical are trained. The longitudinal axis of rotation the Spelser insert 2 (feeder longitudinal axis) is shown by a dashed line Line 20 marked.

The first shaped element 4 is again separately in FIG. 1b Longitudinal section and shown in Fig. 1b in plan view. It's over a molding compound (e.g. insulating or exothermic) shaped and relative thin-walled. The footprint of the first form element 4, with the this sits 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, the first shaped element widens to the maximum outside Diameter of about 77 mm conical, and the conical so defined Section 34 then merges into an upper section 44, which follows 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 Adjacent to section 34 are a total of four to the first shaped element 4 Retaining projections 12 are formed. The (imaginary) connection surfaces between Retaining projections 12 and shaped element 4 are each quite small, so that the Holding projections 12 mechanically from the molded element with little effort can be separated.

A total of four are also assigned to the holding projections 12 Guide and spacer strips 14, which start from the holding projections extend in the longitudinal direction of the feeder insert 2 and opposite the outer wall of the upper section 44 of the lower molding 4 each project by about 2 mm.

1a with its lower edge 26 on the holding projections 12th of the lower molding element 4 is the second (upper) molding element 6. It is molded from an exothermic molding compound and is also quite thin-walled educated. The outer contour of the upper molded element 6 tapers upwards slightly towards one on the outside essentially flat upper wall termination 36. The inner wall of the upper Formula elements 4 initially proceed from its lower edge 26 parallel to the outer wall of the upper section 44 of the lower molding 4 and then goes into a conically tapering wall section 46 above, along which the tip of a centering mandrel at Positioning the feeder insert can be performed. The conical Wall section 46 finally opens into one in the feed axis lying, through the end 36 centering recess 56 for Picking up a mandrel tip.

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

Finally, a centering mandrel 16 is also shown in FIG. which is attached to the model plate 22 and from there (always in the feeder axis of rotation 20 lying) through the feeder passage 10 and through the feeder cavity into the centering recess 56 extends.

The two shaped elements 4, 6 of the feeder insert 2 can be Slide telescopically into each other if parallel to the axis of rotation 20 a force directed onto the model plate 22 (arrow F) on the feeder insert acts, as for example after the filling of molding material Compression molding is the case (see Fig. 3a-d). The force just needs to do this be sufficiently large to hold the retaining projections 12 from the lower mold element 4 separate.

The inner wall of the second (upper, outer) molded element approaches itself when pushed onto the first (lower, inner) form element Outer wall continuously and finally arrives after a displacement path of approx. 15 mm, all around in contact with it. Such a shift path sufficient for many compaction processes. The end position of the lower edge 26 of the upper molded element 6 after covering the above Displacement path is indicated by a dashed line. The Guide strips 14 are 4.6 when pushing the form elements deformed or separated and / or cut into the inner wall of the outer (upper) form elements 6.

The centering recess 56 extends through the upper end wall of the feeder insert 2 and the tip of the centering mandrel includes a cylindrical section that is significantly longer than 15 mm and the diameter of which corresponds to the inner diameter of the centering recess 56 is adjusted. That is why it happens when telescoping the upper one on the lower form element does not cause disability; the thorn tip kicks rather, emerge unhindered from the feeder insert.

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

2 shows an alternative feeder insert 202 according to the invention shown in longitudinal section. In contrast to the feeder insert 2 from the 1a-c comprises the first (lower) molded element 204 of the feeder insert 202 a breaking edge 214. The feeder insert 202 is more compact and thicker walled than the feeder insert 2. The existing one here Centering recess 256 does not pass through the upper feeder end, but extends so far in the longitudinal direction of the feeder insert that an assigned centering pin is inserted far enough into it can be, if the upper mold element 206 telescopically on the lower Form element 204 is moved in the direction of the model plate.

3a-d is an inventive method for arrangement of a feeder insert according to the invention in a casting mold schematically shown. The following explanations apply to the use of feeders 1a-c as well as for the feeder insert from FIG. 2.

3a, a first shaped element 104 is placed on a centering mandrel 116 placed, which is attached to a model plate 122. The form element 104 is in direct contact with the model plate 122 brought.

3b, a second shaped element 106 is then placed on the first shaped element 104 placed so that it is supported by this. To holding projections 112 are provided, for example, in their shape and function of the holding projections 12 explained with reference to FIGS. 1a-c correspond. There is now a composite feeder insert 102 in its starting arrangement, cf. Fig. 1a.

In a subsequent step shown in FIG. 3c, the feeder insert is used 102 coated with molding sand 150 or another molding material (wrapping only indicated in the lower area).

After a compression process, not shown, results the arrangement of FIG. 3d. The holding projections 112 are from the first Molded element 104 broken off, the second (upper) shaped element 106 telescopically a little bit onto the first (lower) shaped element 104 postponed. The displacement path D of the second molding element 106 on the the first shaped element 104 fixed in position is determined by the dimension predetermined and limited the compression of molding material.

Since the outer wall of the second form elements 106 on the between it and the model plate 122 acts like a stamp during the compression process, it comes in this Area for an excellent compression molding (in Fig. 3d by a in comparison with FIG. 3c, denser puncturing of the molding sand 150 is indicated).

Claims (10)

Feeder insert for use in the casting of metals in casting molds, with a cavity for holding liquid metal, characterized in that the feeder insert (2, 102, 202) has at least two molded elements (4, 104, 204 which can be moved into one another along a longitudinal axis of the feeder (20) ; 6, 106, 206) which laterally enclose the cavity for receiving liquid metal. Feeder insert according to claim 1, characterized in that a or on the first, closer to the passage of the feeder insert (2, 102, 202) or forming this form element (4, 104, 204) and / or on the second form element (6, 106, 206) several holding elements (12, 112) are arranged, over which the first shaped element (4, 104, 204) carries the second shaped element (6, 106, 206) and which can be separated or deformed in such a way that the two shaped elements can be pushed into one another along the longitudinal axis (20) of the feeder. Feeder insert according to claim 1 or 2, characterized in that the first shaped element (4, 104, 204) is designed such that it can be inserted into the second shaped element (6, 106, 206). Feeder insert according to claim 3, characterized in that the first molded element (4, 104, 204) is designed such that it can be inserted into the second molded element (6, 106, 206), the outer wall of the first molded element being positively inserted into the inner wall of the second formula element. Feeder insert according to one of the preceding claims, characterized in that the first and / or the second shaped element comprises one or more guide elements (14) which are arranged to tilt or tilt the two shaped elements (4, 104, 204; 6, 106, 206) relative to one another at least substantially to be prevented if they are shifted into one another along the longitudinal axis (20) of the feeder. Feeder insert according to one of the preceding claims, characterized in that a breaking edge (214) is integrated in the first shaped element (4, 104, 204), optionally as part of a breaking core. Feeder insert according to one of the preceding claims, characterized in that a guide for a centering mandrel (16, 116) is integrated in the first and / or second shaped element. Kit for manufacturing a feeder insert (2, 102, 202) according to one of the preceding claims, comprising a first shaped element (4, 104, 204) and a second shaped element (6, 106, 206) arranged in this way that they can be along a longitudinal axis of the feeder (20) are slidable. Method for arranging a feeder insert in a casting mold, with the following steps: Providing a feeder insert (2, 102, 202) according to one of claims 1-7, Arranging the feeder insert in a molding machine so that the first and second molding elements (4, 104, 204; 6, 106, 206) are in an arrangement from which the two molding elements can be moved into one another along a longitudinal axis (20) of the feeder . Filling molding material into the molding machine so that the outer walls of the feeder insert (2, 102, 202) are in contact with the molding material, Compacting the molding sand so that the first and second molding elements are shifted into one another along the longitudinal axis (20) of the feeder. The method of claim 9, wherein the molding machine is a model plate (22, 122) and the first shaped element (4, 104, 204) thus in the Molding machine is used that it is in direct contact with the Model plate stands.

Images