WO1993017818A1 - Process and device for inductively heating at least one insert in a composite casting - Google Patents

Abstract

A process is disclosed for inductively heating an insert (12) in a composite casting, preferably an iron and/or steel materials-based casting. The insert (12) is placed in a casting mould (10) outwardly provided with two opposite recesses (13) that lie on the same plane, and at a distance from the mould cavity (11) and are oriented towards the insert (12). The end pieces (5) of an inductor core (1; 15), upon which is arranged at least one coil (8), are inserted into these recesses (13) and removed after heating. A device for carrying out the process has a C-shaped inductor core (1; 15) (iron core) with a traverse (2; 16) upon which are held core angles (3) provided at their ends with end pieces (5; 18) that point towards each other. Each core angle (3) carries a coil (5; 19) and their mutual spacing is variable by displacing the core angles (3) or the end pieces (5) with respect to the other parts of the iron core. The iron core sections may however also be fixedly linked to each other and core extension pieces (20) may be provided within the heating station between the end pieces (18) on the one side and the insert (12) on the other side.

Description

 METHOD AND DEVICE FOR INDUCTIVE HEATING AT LEAST ONE INSERT FOR A COMPOSITE CASTING PART

ύ The invention relates to a method for inductively defrosters ⁱ 5-cutting of at least one in a mold placed on a partly Einlege¬ Composite casting, preferably on de.r basis of iron and / or steel materials, as well as for carrying out the process suitable device.

10 Such a composite casting consists of an insert or core and a shell or jacket surrounding this core. Materials with different properties are used for the insert and the shell, in order to combine their properties through their combination

15 bring about. For example, a steel with high toughness can be used for the insert and a particularly tough, wear-resistant or resistant metal material for certain requirements can be used for the shell. To create an intimate connection between the insert and the

20 reach, it is necessary to heat the insert before casting.

The production of composite castings by spinning using the inductive heating of the base body or

25 insert is known from DE-PS 748 062. In the device described there, a high-frequency coil is provided which is designed as a single-winded to at most three-winded inductor and encloses the part to be heated. To ensure even heating

30, the inductor parts are coupled unevenly. In the case of larger parts to be heated, inductor coils through which current flows in opposite directions are to be used, as a result of which the heating effect is increased at the ends.

35 A disadvantage of this known device is that the direct adaptation of the inductor to the part to be heated, which at the same time forms the contour wall is, only rotationally symmetrical composite castings can be produced.

It is also known (DD-PS 294 646) to avoid the formation of gas bubbles at the interface between the parts to be poured in and the solidifying casting metal in the production of composite castings by heating the entire mold with a separating layer before pouring. The heating of the separating layer is accomplished, inter alia, by attaching cables from a power transformer to the separating layer, for example to a sheet steel sleeve lying in the casting mold. The current flowing through the steel shell is intended to heat it up.

The disadvantages of the resistance heating used here of the separating layers lying in the casting mold is that in the case of composite castings the power supply lines are not completely embedded in the molding material and thus melt during the casting and thereby cause quality losses. The complicated introduction of the cables into boxless casting molds is also not technically economically viable.

Furthermore, it is known (EP 0 206 963 B1) to form a C-shaped inductor core with mutually facing pole pieces from two pivoting legs or branches which are coupled via an articulated connection and an adjustment of the distance between the legs of the inductor possible to cover this distance eg to adapt to the thickness of a metal strip.

DE 41 09 308 C1 discloses a method for producing a cylinder of an internal combustion engine, in which a steel ring, surrounded by an induction coil, is placed and heated in a casting mold. The mold is then filled with liquid gray cast iron. A disadvantage of this method is that the induction coil is integrated into the casting mold is and does not allow adaptation to the dimensions of different built-in parts.

From WO 91/15093 A1 a heating device is known which comprises an inductor which has a C-shaped inductor core made of a traverse and core angles held thereon, which at their ends have end pieces directed towards each other, each with a coil, wherein the distance between the end pieces can be changed. This known heating device is intended for heating objects made at least partially of metal.

The object of the present invention is to provide a method of the type mentioned at the outset and a device suitable for carrying it out in such a way that, without any restriction to rotationally symmetrical composite castings, an energy-saving, economical heating of the inserts and thus an improvement in the composite castings overall becomes possible.

This object is achieved according to the invention by a method which is characterized in that the casting mold for each insert part is provided from the outside with two recesses which lie opposite one another in one plane and end at a distance from the mold cavity and aim at the insert part that parts of an inductor core provided with at least one coil are introduced into the cutouts and that the coil (s) are / are then connected to a power source for inductive heating of the insert part.

According to this method, the air gap between the end regions of the inductor on the one hand and the insert part on the other hand is reduced and a better conversion of the electrical energy into heat for heating the insert part is brought about. This process is particularly applicable to castless casting foils, but can also be used in connection with casting boxes, which must then have passages in the area of the cutouts.

The method according to the invention can also be carried out in such a way that the casting mold with the insert part (s) is brought into a heating station and that end pieces of the inductor core are introduced into the recesses in this station. Known C-shaped inductor cores can be used here, the end pieces of which can be moved towards one another in order to be brought as close as possible to the insert to be heated in accordance with the respective circumstances.

The method according to the invention can also be carried out in such a way that the end pieces of the inductor core with coils accommodated thereon are introduced into the cutouts in the heating station. If the coils are also introduced into the recess, the electrical efficiency of the induction heating is thereby improved. On the other hand, a correspondingly larger cross section is required for the recess.

The method according to the invention can also be carried out in such a way that core extensions are introduced into the cutouts and that the casting mold is then brought into the heating station in which the core extensions are aligned with the end pieces of the inductor core. The individual sections of the inductor cannot be displaced relative to one another, so that the distance between the end pieces of the inductor cannot be changed. It can therefore be worked with a particularly simple inductor. The core extensions are used to adapt to the respective conditions of the shape, with which deviations in the respective dimensions of the shape can be compensated. To carry out the method according to the invention, a device of the type mentioned at the outset is designed such that separate core extensions which can be aligned with the end pieces of the inductor core and can be introduced into the cutouts in the casting mold are provided.

Finally, the invention provides for the use of a device with an inductor provided with at least one coil for inductive heating according to the invention of at least one insert for a composite casting, the inductor having a C-shaped inductor core (iron core) with a cross member and two held thereon Has core angles, the ends of which are directed towards each other and each have a coil, the spacing of which can be changed from one another.

In the following part of the description, exemplary embodiments of the method according to the invention and devices suitable for carrying it out are described. It shows:

1 is a perspective view of a first embodiment of the device according to the invention with displaceable core angles on the roller conveyor of a molding installation,

2 shows an end view of a further embodiment of the device according to the invention with core extensions and

3 shows a cross section through the end piece of an inductor with a coil.

The embodiment of the device according to FIG. 1 has a C-shaped inductor core 1, which is formed from a horizontally arranged cross member 2 and two core angles 3, each of which has a leg 4 and an adjoining one, parallel to the cross member 2 trending tail 5 exist. The end pieces 5 are directed towards one another.

The core angles 3 can be displaced along the cross member 2 by means of a drive 6 in order to be able to change the distance between the end pieces 5 from one another.

The inductor core 1 as a whole is supported by supports 7.

On the end pieces 5 there is a coil 8, which is connected to a power source, not shown.

1 also shows a roller conveyor 9 on which molds can be transported and finally transported to a casting station (not shown). 1 shows the heating station in which a boxless casting mold 10 is located. The casting mold 10 has a cavity 11 in which an insert 12 is placed. Ultimately, this insert 12 is to be cast around with another material in the pouring station and thus encased.

In the casting mold 10, recesses 13 are provided which extend from their outer sides and run transversely to the transport direction of the roller conveyor 9, are directed towards one another and thereby aim at the insert 12. The recesses 13 end at a distance in front of the inner surface of the cavity 11, so that here a wall formed from molding material of sufficient stability remains for the subsequent pouring.

In the heating station, the recesses 13 are aligned with the end pieces 5, so that the end pieces 5 together with the coils 8 can each be introduced into a recess 13. Thus, the end pieces 5 are brought close to the insert 12 to be heated.

First, the mold 10 is formed. The insert 12 is placed precisely in its cavity 11. there the mold 10 is provided with the recesses 13. The casting mold 10 is then brought on the roller conveyor 9 into the heating station, in which the cutouts 13 are aligned with the end pieces 5. Then the core angles 3 are moved towards each other by means of the drive 6, the end pieces 5 with the coils 8 entering the recesses 13, the core angles 3 can be pressed against the cross member 2 by means of pressure elements indicated by arrows 14 to bring about an optimal guidance of the magnetic field between the parts of the inductor core. The power supply to the coil 8 is switched on and the insert 12 is heated inductively. When the insert 12 has reached the desired temperature, the power supply to the coils 8 is interrupted and the core angles 3 are moved away from each other again, so that the end pieces 5 emerge from the recesses 13. The mold 10 is then transferred to the pouring station.

In the embodiment according to FIG. 2, a C-shaped inductor core 15 is provided, which has a cross member 16, legs 17 proceeding therefrom and finally parallel to the cross member

Has 16 extending towards each other end pieces 18 on which coils 19 sit. The crossbeam 16, d ^'ie leg

17 and the end pieces 18 are immovably connected to each other.

In this embodiment too, a casting mold 10 with a cavity 11 and an insert 12 placed therein is provided. Here too, the casting mold 10 is provided with cutouts 13.

In the heating station shown in Fig. 2 13 core extensions 20 are arranged in the recesses, which largely bridge the distance between the end pieces 18 on the one hand and the insert 12 on the other. The core extensions 20 are aligned with the end pieces 18 in the heating station and are adapted to them in terms of material and dimensions. The procedure is such that the casting mold 10 is produced with the insert 12 in the manner described above and is provided with a recess 13. Before the casting mold 10 is transported into the heating station, the core extensions 20 are placed in the cutouts 13. In the heating station, the cutouts 13 with the core extensions 20 therein are aligned with the end pieces 18. The inductive heating then takes place without changing the distance between the end pieces 18. After the heating phase has ended, the core extensions 20 are removed from the cutouts 13. The casting mold 20 is then transported on to the pouring station.

Fig. 3 shows a coil 19 which sits on an end piece 18. This results in an intermediate space 21 between the end pieces 18 and 19, which is filled with a heat-conducting inorganic mass in order to cool the end piece 18 by cooling the coil 19.

The process of the invention is to the example of the series even producing a digging tool designed as Verbundgußtei1 _^ are explained in detail. The insertion part 12, which is to form the core of the digging tool, is placed in a boxless casting mold 10. The insert 12 consists of a tough material GS-50, which is to be coated with the wear-resistant material GX-260Cr27. The weight, size and shape of the insert 12 are known. The coils 8, 19 are supplied with electrical energy, this being coordinated so that the insert part 12 is heated to 450 ° C. in the example described here. After heating, the mold 10 is immediately transported to the pouring station.

The transport of the casting mold 10 as well as the energy supply of the coils 8, 19 and the displacement of the core angle 3 are controlled by a computer.

Claims

Expectations 1. A process for inductive heating of at least one insert part for a composite casting, preferably based on iron and / or steel materials, characterized in that the casting mold for each insert part is from the outside with two in one plane opposite recesses, which end at a distance in front of the cavity of the mold and are aimed at the insert, that parts of an inductor core provided with at least one coil are introduced into the recesses and then the coil / coils for inductive heating of the insert is / are connected to a power source. 2. The method according to claim 1, characterized gekennzeich¬ net that the casting mold with the insert / the insert parts len is brought into a heating station and that end pieces of the inductor core are inserted into the recesses in this station. 3. The method according to claim 2, characterized gekennzeich¬ net that in the heating station the end pieces of the inductor core with coils accommodated thereon are introduced into the recesses. 4. The method according to claim 1, characterized gekennzeich¬ net that core extensions are introduced into the recesses and that the mold is then brought into the heating station in which the core extensions are aligned with the end pieces of the inductor core. 5. Suitable for carrying out the method according to any one of the preceding claims with an inductor provided with at least one coil, which has a C-shaped inductor core (1; 15) with a crossmember (2; 16) and two core angles (3) held thereon , which at their ends are directed towards each other and each have a coil (8; 19) carrying end pieces (5; 18), the spacing of which can be changed, characterized in that the end pieces of the inductor core can be aligned into the recesses of the Castable separate core extensions are provided. 6. Use of a device with an inductor provided with at least one coil, which has a C-shaped inductor core (1; 15) with a crossmember (2; 16) and two core angles (3) held thereon, which at their End-facing end pieces (5; 18) each carrying a coil (8; 19), the spacing of which can be changed, for inductive heating according to one of Claims 1 to 4.