EP1000688A1 - Process and installation for producing aluminium castings with inserts - Google Patents

Abstract

Producing the castings involves the use of mold boxes (e.g. 1). Inlays (9) are heated after they have been placed in the lower box. The mold is then closed by putting the upper box in place. The molds (e.g. 2) are then cast. The inlays are heated to a temperature above the melting point of aluminum, and are still at a temperature in the region of the melting point when cast.

Description

The invention relates to a method for producing Aluminum castings with inlays from another Composite casting material by molding sand over a model compressed in one of two mold boxes forming the mold in the shape of at least one molding box the inserts and, if applicable, mold cores and both mold boxes closed by adding a sand mold be, the deposits before pouring the Form on an external heater Temperature in the range of the solidus temperature of aluminum be heated.

Furthermore, the invention is directed to a plant for Manufacture of aluminum castings with inlays another material in composite casting, with at least a molding machine for the production of two-part Box shapes, at least one transport route for the horizontal transport of bottom box shape and top box shape, at least one on the transport route arranged insertion station for inserting mold cores and deposits in the lower box, an upper box and Merging sub-box shape into a closed shape Feeder and a subsequent casting station, an external heating device for heating the Deposits at a temperature in the range of the solidus temperature of aluminum is provided.

Aluminum is becoming increasingly popular as a construction material Importance as it has the positive properties of a minor Weight, high corrosion resistance, one good thermal conductivity and in many cases sufficient Strength values combined with each other. It will therefore today many technical components made of aluminum manufactured. This also applies to automotive engineering, especially for engine blocks with the advantage of a higher power to weight ratio and simultaneous reduction of fuel consumption.

When such technical components made of aluminum in certain Areas subject to special loads, which aluminum does not do justice to deposits made of materials that meet these requirements are enough. These are for aluminum engine blocks especially the cylinder liners, with liners made of wear-resistant sliding material. The difficulty is between the cast aluminum and the insert a perfect, permanent connection to manufacture. With the so-called pouring of deposits, in which the insert is partially melted by aluminum is enclosed, there is no metallic, intercrystalline connection between the casting metal and the deposit. Here must be by appropriate constructive Design for a positive and non-positive connection be taken care of by shrinking and / or Pouring undercuts etc.

In composite casting, a metallic, intercrystalline Connection created between the insert and the casting. It is necessary for components, the strong dynamic or thermal alternating stresses. Here again are engine blocks and especially theirs To name cylinder surfaces. For composite casting essentially two methods are known. With the ALFIN process the insert is covered with a thin aluminum layer busy. This happens because the Insert in an overheated aluminum melt of approx. Immersed briefly at 850 ° C and then optionally in a melt of 600 ° C is "quenched". In this The insert remains in the melt until shortly before insertion in the composite casting mold, so that the insert approximately the has the same temperature as the subsequently cast Melt.

Another process will be fat-free and metallic bare inserts into the mold when cold inserted and the mold closed. Through separate openings or channels in the form that extend into the area of the deposits will be induction heating in the Form introduced up to the deposits and become the deposits down to the solidus temperature range of aluminum heated up. This takes place in the boundary layer of Insert and casting a surface diffusing the Metal atoms taking place to form a kind of alloy. This procedure is particularly useful when equipping from aluminum engine blocks with cylinder liners Gray cast iron, so-called liners, applied.

In the aforementioned cases, the engine block is in two parts Sand molds (boxless or boxbound) in always poured vertically. It says so Core package or the finished engine block either on the Crankcase or on the cylinder head side. The cylinder axis lies in the mold parting line and the shapes also point in the mold parting line from the outside up to channels of sufficient diameter leading the inserts through which the heating rods up to the inserts be immersed. After heating up the heating rods drawn and the mold clocked into the casting station and poured. This is the production method for boxless molds at least for engine blocks of in-line engines sensible, but not executable for V-engines.

In the case of box-bound molds, the mold box wall is cut through the relatively large openings required for the heating elements, those corresponding to the number of cylinders Number must be present, greatly weakened. This again, certain molding sand compaction processes are closed, working with high pressure, especially pneumatic Compression process, from or must be with a corresponding lower mold hardness can be worked again, casting problems and easy to prepare Surface defects leads. Also leave with this method V-engine blocks are not realized because the under cylinder axes at an angle to the mold parting plane cannot be reached with heating elements.

All known boxless or box-bound workers Molding processes also have the disadvantage that only two Engine blocks can be arranged side by side in a form can, so the performance of such systems significantly lags behind that of conventional gray cast iron systems.

The invention has for its object a method and to propose a plant that will manufacture any aluminum castings with inlays at the same time Performance increase over conventional Facilities.

Based on the procedure mentioned at the beginning, the at the same time forms the preamble of claim 1 solved this problem in that with a horizontal arrangement the molded box the inserts after inserting them into the open lower box are heated up immediately afterwards the form is closed by adding the top box and then the mold is poured, whereby the deposits to such a temperature above the Solidus temperature of the aluminum are heated that their temperature when pouring the mold in the range of Solidus temperature is.

The method according to the invention first uses the advantages the horizontal arrangement of the molding box, as in Gray cast iron plants are known, in particular in one relatively easy handling and high performance too are seen. As with gray cast iron systems, the invention works Procedure with lower and upper box, in which a part of the mold is molded, with the cores in usually only in the open, lying on the back Lower box can be inserted from above. Like the kernels or -in the case of engine blocks- the core package will also be the Deposits made of the different kind of material on appropriate Support inserted and on the relatively easily accessible open lower box heated. Then will the form closed by closing the top box and the shape that remains horizontal or vertical is set up, filled with the molten aluminum. The insoles are heated to a temperature that sufficiently above the solidus temperature of the aluminum lies between the heat emission between the heating of the To compensate for deposits and pouring the mold and ensure that the inserts have another cast sufficiently high temperature in the range of the solidus temperature of aluminum.

Contrary to all expectations, this can be known from the realize high cycle times of such molding plants without any problems. The heat release in the sand mold is because of the poor thermal conductivity of molding sand relatively low, so that heat is emitted primarily by radiation becomes. Since there is no air convection in the closed form heat loss in the mold is relative low. This applies especially to liner for the Cylinders of engine blocks, as in the form between the Outside of the liner and the adjacent core areas there are only relatively narrow gaps.

In practice it has been shown that the residence time of the Form between the heating of the insoles and the pouring the shape even has a favorable effect. Because it is in the known method due to that for heating available short time and the existing Geometries hardly possible, the insert over their entire Expansion and wall thickness to the same temperature bring to. The residence time in the process according to the invention leads to temperature compensation through heat conduction within the insert, so that the insert when Pour the same temperature over its entire extent owns. The in the method according to the invention necessary temperature increase when heating the insert is in the range of 50 ° C.

In box systems, especially for gray cast iron, in the Rule the casting masses approximately evenly on the lower box and distributed the top box. Are in the concrete If the insoles are then mostly in the lower box shape and are, for example, only accessible horizontally, it may be advisable to use the form with the cores and Deposits with regard to the mold parting plane of top box and Lift the lower box so that the external heating device can be introduced to the deposits.

If the form has several inserts, all of them can or in groups by means of a single heating device would be heated by this one of the in the Group existing number of deposits corresponding number of heating rods.

With a horizontal box transport there are often several Core loading stations or post-processing stations arranged one behind the other. This gives the opportunity to Deposits to be heated in multiple stages or to temperature hold.

The method according to the invention is - in contrast to all known sand molding process - particularly suitable for Manufacture of engine blocks for V-engines. It says the shape on the side of the crankcase, during the Upper box takes the upper part of the engine block. The corresponding core package is therefore with the cores and the cylinder liners above the horizontal mold parting line so that the liner can easily be viewed from above the heater, under an appropriate Has angularly arranged heating rods are accessible.

For aluminum engine blocks for inline engines, at which the cylinder liners are made of a wear-resistant As with V-engines, sliding materials exist the bushings are inserted into the core package for the engine block. In the horizontal provided according to the invention Arrangement of the molding box, the core package with horizontal Axle inserted into the shape of the lower box in such a way that the horizontal cylinder liners are above the mold parting plane, so that the external heating device horizontally into the cans can.

There can be at least two engine block shapes in the upper and lower box with the crankcase facing each other be molded. However, four engine blocks are preferred Molds arranged in pairs in a mold box united. The method according to the invention is therefore in Contrary to all known methods the possibility the cluster arrangement.

With the method according to the invention, the Possibility to choose the closed molding box in a horizontal or vertical position by increasing Pour to fill with the molten aluminum.

The increasing casting of aluminum has compared to that Gravity casting has the advantage that the melt does not tumbles into the mold turbulently, causing irregularities in the structure, lead to oxide skin formation etc. Moreover has the increasing pouring with horizontal mold boxes Advantages compared to vertical mold boxes, because the climbing height is lower and even at high ones Melt flow no turbulence arise, so that a higher casting performance is possible.

As preferred, the shapes of engine blocks are in pairs facing each other, the shapes are from the center of the molding box poured together.

In a system of the structure mentioned at the beginning, which The preamble of claim 10 corresponds to the object of the invention in terms of device technology solved that the heater on or after the loading station arranged and from a standby position in the position of the deposits and back can be moved, and that the feeder immediately behind the station the heating device and the pouring station immediately is arranged behind the feeder.

Due to the design of the system according to the invention between the station where the insoles are heated and the casting station only one position with the Feeder, so that between heating and pouring there are only two work cycles. Because the shape and the Molding box has no openings or channels for insertion of heating rods or the like., The shape made with any compression method become.

As with conventional cast iron systems, one can single molding machine alternately top box and bottom box are molded, which are then alternately on the Back or on the head promoted on the transport route become. In the open lower box the Cores and deposits used. After the last station with the heater, the lower box gets into the Feeder and is the one already recorded there Upper box on the lower box while closing the mold put on. The mold then runs out of the feeder expediently immediately into the casting station.

In another known plant for gray cast iron Lower box and upper box separated from a molding machine molded and on its own transport route promoted. So here the sub-boxes arrive immediately one after the other into the core insertion station or stations. This gives the opportunity to make deposits to heat up before the last station and in the following stations to arrange further heating devices to the Preheat deposits, heat to final temperature and then keep warm.

The heater can be between the core insertion station and the feeder can be carried with the lower case, so that the heating during transportation between these two positions.

Finally, according to one embodiment, that at the casting station of such a system Melting furnace with riser pipe for connection to the molding box is arranged for the rising pouring.

Fig. 1

einen schematischen Schnitt einer Unterkastenform mit eingelegten Kernpaketen für die Herstellung von Motorblöcken für Reihenmotoren;

Fig. 2

einen schematischen Schnitt der Unterkasten- und Oberkastenform während des Zulegens des Oberkastens;

Fig. 3

einen schematischen Schnitt einer Unterkastenform zur Herstellung von Motorblöcken für V-Motoren einschließlich Heizeinrichtung;

Fig. 4

einen der Fig. 2 entsprechenden Schnitt von Unterkasten- und Oberkastenform während des Zulegens des Oberkastens;

Fig. 5

eine Draufsicht auf einen Teil einer Formanlage und

Fig. 6

eine Ansicht eines Teils einer anderen Ausführung der Formanlage.

The invention is described below with reference to some exemplary embodiments shown in the drawing. The drawing shows:

Fig. 1

a schematic section of a lower box shape with inserted core packages for the production of engine blocks for inline engines;

Fig. 2

a schematic section of the lower box and upper box shape during the increase of the upper box;

Fig. 3

a schematic section of a lower box shape for the production of engine blocks for V-engines including heating device;

Fig. 4

2 corresponding section of bottom box and top box shape while the upper box is being added;

Fig. 5

a plan view of a part of a molding plant and

Fig. 6

a view of part of another embodiment of the molding system.

The drawing is based on the manufacture of Engine blocks with inserted cylinder liners, so-called Liners are described, however, the procedure and the Plant according to the invention also for the production of any other technical components made of cast aluminum with Deposits applicable.

In Fig. 1, a conventional sub-box 1 is shown in which in a conventional molding machine Lower box mold 2 by compacting molding sand over a model is made. The production takes place in usually on the head, i.e. in a compared to Fig.1 position rotated by 180 °. In the lower box form 2 in the embodiment shown also a central Sprue 3 molded in from below for increasing pouring, the via distributor 4 connection to the mold rooms of the Has bottom box shape 2.

There are two core packages in the open bottom box shape 2 5 for the production of engine blocks for in-line engines inserted, in such a way that the cores 6 for the Crankcases are facing each other while the Cylinder head side 7 is located on the outside. In the cylinder bores 8 are the liners 9 from one wear-resistant sliding material used.

At the station of a transport route shown in FIG. 1 there are heating devices on opposite sides 10 with induction heating elements 11, the are horizontally retractable into the liner 9 from the outside, such as this is indicated by double arrow 12. The heating rods 11 are preferably in register according to the number the cylinder arranged and movable together. To do that To immerse the heating rods 11 are the Core packages 5 with their axis above the mold parting plane arranged, that is to say about their usual position raised half the diameter of the liner. At the station 1, the liners 9 are at a temperature heated up above the solidus temperature of the aluminum lies. When the desired temperature is reached the heating rods 11 are pulled and in the next working cycle, 2 shows the top box 13 with the top box shape 14 increased and the form closed. The Upper box shape 14 can 15 and on this or optionally have additional feeders. The closed one Form is then pouring from the bottom poured over the sprue 3.

Fig. 3 again shows a lower box 1 with the lower box shape 2, but in this case for the production of Engine blocks for V-engines. In this use case the core packs 16 sit with the crank-side part in the lower box shape 2, while the cylinder head side Parts of the core package are exposed above the mold parting line. In the cylinder bores of the core package 16 are in turn liner 17 used by means accordingly angularly adjusted heating rods 18 are heated can. The heating rods 18 may sit on after inside bent leads to them in the axial direction to be able to retract and extend in a space-saving manner. Are the liners 17 heated to the desired temperature, is then the upper box 13 with the upper box shape 14 increased and the form closed. Then hikes the molding box into the casting station.

Fig. 5 shows a plan view of a section of a Molding plant with a molding station 20 and one on it subsequent transport route 21 with core insertion station 22 and one arranged at the head of the transport route 21 Feeder 23, which also the transport route 21 with a casting and cooling section 24 connects to casting station 25. Sub-box molds are alternately formed in the molding station 20 2 (FIGS. 1 and 3) and upper box shapes 14 (Fig. 2 and 4) made, the lower box shape is then turned so that it is open at the top is. The lower box 2 and upper box shapes 14 are given alternately on the transport route 21, get there first in an insertion station 26, in the for example the core packages 5 with the liners 9, for example 1 used in the lower box shape 2 become. After two further transport steps the bottom box molds 2 reach station 27, in of the heating rods 11 of the heating device 10 horizontally in the liners are retracted from both sides and this Heat up to above the solidus temperature. In the same Work cycle is a leading top box shape 14 in the Feeder 23 arrives and has been lifted there. To Pulling the heating rods 11 will be in the next cycle Lower box shape 2 with the heated liners in it Feeder 23 promoted the top box shape located there 14 placed on the lower box shape 2 and the closed molding box on the transport route 24 transported and by means of a shock drive 28 in the Casting station 15 implemented in the closed molding box from below via the sprue 3 and the distributor 4 (Fig. 1) is poured rising from below.

Instead of just one molding machine, as shown in Fig. 5, can also be provided two molding machines that parallel transport routes are arranged and each only produce lower box molds or upper box molds. These then move on the parallel transport routes in the same direction to a feeder that is similar the feeder 23 is formed and the transport routes bridged at her head. Part of a such system is shown in Fig. 6, which is only the transport route 29 for the sub-box forms that in this case, run one after the other. Immediately in front of the feeder 23 is another Station 27 arranged with the heating device 10. Right away behind the feeder 23 is the casting station 25 with a melting furnace and one not shown Riser pipe, which may be mobile, to the Connect the riser pipe to sprue 3 below.

Instead of the exemplary embodiments shown, the casting can the shapes are also in a vertical position, into which they are placed behind the feeder.

Claims (14)

Process for producing aluminum castings with inserts (9) made of another material in the Composite casting by molding sand over a model in each one (1) of two mold boxes (1, 13) is compressed into the shape of at least one Molding box (1), the inserts (9) and, if necessary Mold cores (5) inserted and both mold boxes (1, 13) closed by adding to a sand mold (2, 14) the inserts before pouring the mold by means of an external heating device (10) Temperature in the range of the solidus temperature of the Aluminum are heated, characterized in that with a horizontal arrangement of the molding box (1, 13) the inserts (9) after insertion in the open lower box (1) are heated up immediately then the shape by adding the top box (13) closed and then the form (2, 14) is poured, the inserts (9) on a such temperature above the solidus temperature of the aluminum are heated so that they Pour the mold off a temperature in the area the solidus temperature. A method according to claim 1, characterized in that the form (2, 14) and the cores (5) and deposits (9) with regard to the mold parting plane of the upper box (13) and bottom box (1) are arranged so that the external heating device (10) to the inserts (9) can be introduced. A method according to claim 1 or 2, characterized that the inserts (9) of a form (2, 14) all or in groups by means of the heating device (10) be heated. Method according to one of claims 1 to 3, characterized characterized in that the deposits (9) in several stages heated or kept at temperature. Method according to one of claims 1 to 4 for Manufacture of engine blocks for in-line engines, by cylinder liners (9) from a wear-resistant Material in the core package that molds the engine block (5) are inserted, characterized in that the core package (5) with essentially horizontal Axis in the form (2) of the lower box (1) is inserted that the horizontal cylinder liners (9) lie above the mold parting line, and that the external heater (10) is horizontal is immersed in the cylinder liners. A method according to claim 5, characterized in that in the molding box at least (1, 13) two engine block molds with the crankcase facing each other be molded. A method according to claim 6, characterized in that in the molding box (1, 13) four engine block molds in pairs with the crankcase facing each other be molded. Method according to claim 6 or 7, characterized in that that the mutually facing forms of poured together in the middle of the molding box become. Method according to one of claims 1 to 8, characterized characterized in that the closed molding box (1, 13) in a horizontal or vertical position rising pouring filled with the aluminum melt becomes. Plant for the production of castings from aluminum with inserts (9) made of another material in the Composite casting, with at least one molding machine (20) for the production of two-part box molds, at least one transport route (21) for the horizontal transport of lower box mold (2) and Upper box shape (14), at least one on the transport route arranged insertion station (26) for Insert mold cores (5) and inserts (9) in the Lower box (1), an upper box (14) and lower box shape (2) to a closed form (2, 14) merging feeder (23) and a subsequent Casting station (25), with an external Heating device (10) for heating the inserts (9) to a temperature in the range of the solidus temperature of aluminum is provided, characterized in that that the heater (10) on or after the insertion station (26) arranged and from a Ready position in the position of the deposits (9) and can be moved back, and that the feeder (23) immediately behind the station (27) with the Heating device (10) and the casting station (25) immediately is arranged behind the feeder (23). Plant according to claim 10, each with a molding machine for the separate production of lower box (2) and upper box molds (4), one each on the molding machines connecting transport route for the Lower box (2) or upper box shapes (14), at least a core insertion station (26) on the lower box transport route (29) and one arranged after that, bridging both transport routes Feeder (23), characterized in that on the Transport route (29) for the lower box molds (2) at least at the last station (27) before An external heating device (10) is arranged. Installation according to claim 11, characterized in that several on the lower box transport route (29) Stations with one external heating device each (10) are provided. Plant according to one of claims 10 to 12, characterized characterized in that the heating device between the Core insertion station (26) and the feeder (29) with the bottom box shape (2) can be carried. Plant according to one of claims 10 to 13, characterized characterized in that at the casting station (25) Melting furnace (30) with riser pipe for connection to the Molding box (1, 13) arranged for the rising pouring is.

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