CA2031009A1 - Method of manufacturing a composite component - Google Patents

Abstract

ABSTRACT

In a method of manufacturing a composite component an outer shell is shrunk onto a ceramic inner member. In order to achieve a uniform heating of the outer shell and to be able to position the inner member within the outer shell in a still uniformly heated state of the outer shell, the outer shell is heated by means of inductive heating. The inner member is then introduced into the heated outer shell and positioned in it. The composite component is fixed by subsequent cooling.

Description

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-1- 23843-2~2 METHOD OF MANUFACTURING A COMPOSITE COMPONENT

DESCRIPTION

The invention relates to a method of manufacturing a composite component by shrinking an outer shell onto a ceramic inner member wherein the outer shell is heated and finally the composite component is cooled after mutual positioning of the outer shell and the inner member.

Such a method is described in DE 3527793 C2 for manufacturing a gas flushing brick. In this, the sheet metal sleeve forming the outer shell is heated by means of a flame or a heating furnace. In at least the first mentioned case, the heating of the sheet metal sleeve is non-uniform such that certain zones o the sheet metal sleeve remain cooler than others. This results in a differential expan~ion of the sheet metal sleeve.
This is unfavourable for the subsequent shrinking-on process. When connecting together the outer shell and lnner member, which ls not simple due to small tolerances and the high temperatures, the sheet metal shell cools prematurely at the outer edges so that uniform ~hrinklng-on does not occur. This applies aqually lf the outer shell ls heated in a heating furnace.

The hot sheet metal sleeve is grasped by means of plncers or the like and transferred to the moulded brick. Means whlch engage the sheet metal sleeve additionally cool the sheet metal sleeve in the engagement zone. The sheet metal sleeve is thus no ~3~3 longer uniformly expanded when it is finallv slid onto the moulded brick. Thus the means for gripping the hot sheet metal sleeve results in deformation.

Furthermore, the method in accordance with DE 3527793 is also not very economical since the thermal radiation from the sheet metal sleeve before it is positioned is considerable.

A method of assembling a gas flushing brick is descri~ed in DE 3538421 A1. In this, a sheet of refractory paper is inserted between the moulded brick and its sheet metal sleeve. This can comprise ceramic fibres. The paper layer i9 intended to prevent undesired gas passages which can remain during the shrinking-on process.

It is the ob~ect of the invention to propose a method of the type referred to above by which the entire outer shell is uniformly heated and in which the inner member can be positioned in the outer shell in a condition in which it is still uniformly heated.

In accordance with the invention, the above ob~ect is solved in a method of the type referred to above if the outer shell i~ heated by means of inductive heating and if thereafter the inner member i~ introduced into the outer shell, which is maintained at a desired temperature level, and positioned in it.

As a result of the inductive heating the outer shell heats up uniformly over its entire surface. The hot outer shell does not need to be handled thereafter.

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The inner ~ember is then slid into the outer shell and positioned in it in the desired final position. The inductor is switched on so long that on the one hand the temperature of the outer shell does in any event not fall below a predetermined minimum temperature and on the other hand no so-called dark spots are produced which are indicative of the premature local cooling. A
good thermal insulation of the inductor has a favourable effect in this connection.

Thereafter the outer shell is cooled whereby it shrinks onto the inner member. The cooling can be effected by switching off the inductive heat source. The cooling can also be effected by exposing the composite component to room temperature. In exceptional cases, cooling means can, however, also be provided.

Another solution to the ob~ect i9 characterised in that the inner member and the outer shell are assembled and the composite component is exposed to an inductive heat source and that thereafter the inner member is positioned in the outer shell whose temperature is maintained. The inner member is thus placad against the outer shell even before the outer shell is heated.
This can be e~fected with, for instance, a conical or frusto-conical shape of the outer shell and the inner member. The outer ~hell and the inner member are then sub~ected to the inductive heat source. This heats the outer shell more strongly than the inner member so that the outer shell expands with respect to the inner member and the inner member can thereafter be moved into the desired position within the outer shell.
Thereafter the inductive heat source can be switched ~3~

off .

In both solutions the outer shell is uniformly heated and the inner member is positioned within the outer shell. The hot outer shell does not need to be engaged or moved to the inner member and positioned in a complicated manner so that it is not cooled, even locally, by such method steps.

The fact that the hot outer shell only has low heat losses in a space which is matched to it and is defined by an adjustable inductor and renders only a small air gap possible, ha~ a favourable effect on the energy requirement of the method. A good thermal insulation reinforces this effect. The method is relatively simple since the hot outer shell does not need to be handled.

In a ~referred embodiment of the invention the outer shell is metallic and thus inductively heatable without any difficulty. The outer shell can, however, comprise an inductively heatable ceramic material. With a ceramic materlal, which iq only electrically conductive and thu~ inductively heatable above a certain temperature, for instance yttrium-stabilised zirconium oxide, the outer shell is preheated to this temperature.

The ceramic inner member can be plate-shaped and the outer shell of annular strip-shape. The method is thus suitable for shrinking-on rings, for instance onto sliding plates of a valve of a vessel for a metal melt.

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The outer surface of the ceramic inner member and the inner surface of the outer shell associated with it can be cylindrical and/or conical and/or frusto-conical.
The method is thu~ suitable also for shrinking on an outer shell of a gas flushing brick of a vessel for a metal melt. In this case the ceramic inner member can be porous or have gas passages.

In order to compensate for any undesirably high manufacturing tolerances and/or large non-uniformities between the inner member and the outer shell at the ad~oining surfaces of the inner member and/or the outer ~hell, a temperature-reqlstant intermediate layer is applied, in one embodiment of the invention, externally of the inner member or internally within the outer shell before positioning the inner member in the outer shell, whereby the intermediate layex is d~formable by manufacturing tolerances or non-uniformities between the inner member and the outer shell.

A subctantial further advantage of the intermediate layer resides ln the fact that it acts at the same time as an elastic buffer. It can thus damp impacts acting on the outer shell or the inner member with respect to the inner member and the outer shell, respectively.
This ls particularly favourable if the composite component is a ~oot particle filter or a catalyst in a motor vehicle.

In a further embodiment of the invention the outer shell is intr~duced into an inductor connected to a frequency inverter and heated by it to 500C to 1000C, preferably to 800C to 950C. Thereafter the ceramîc 2 ~ J

inner member is introduced into the ~uter shell and positioned in its predetermined co~posite position.
The frequency inverter is fi~ally switched off and the composite component removed from the inductor. An inductor suitable for this purpose with a frequency inverter is known in the market. The cooling and thus shrinking-on of the composite component begins when the frequency inverter is switched off. When removing the composite component from the inductor the outer shell can already be firmly seated in the inner member.
Cooling to room temperature occurs outside the inductor.

In a further embodiment of the second solution to the ob~ect, the outer shell and the ceramic inner member are assembled outside an inductor. This composite component is then introduced into an inductor connected to a frequency inverter. ~he outer shell is heated in it to 500C to 1000C, preferably to 800C to 950C.
The ceramic inner member expands less in comparison to the outer shell. The inner member is then positioned in its predetermined composite position and the frequency inverter is switched off. The composite component i~ finally removed from the inductor. In this case also the outer shell shrinks after being positioned directly after the switching off of the freguency inverter.

It has been found that a frequency inverter with a nominal power of 12kW to 30kW, preferably 25kW, and a frequency of 4kHz to 12kHz, preferably 7kHz to 1OkHz as the frequency inverter is suitable for the method.

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A preferred further embodiment of the first solution is characterised in that the outer shell is introduced preferably from below into the inductor and fixed in position. The inductor is heat-insulated on all sides and closed, for which purpose a flap can be mounted in front of the supply opening. ~he frequency inverter is switched on until the desired temperature of the outer shell is reached. Experience shows that this occurs after 10s to 60s, preferably about 20s to 30s. The ceramic inner member is then introduced, also from below, into the outer shell and positioned therein. Subsequently or even during the of the ceramic inner member, the frequency inverter is switched off and finally the composite component is removed downwardly from the inductor. The energy requirement of this method is comparatively low since the inductor is closed and is only switched on when the outer shell has been inserted lnto the inductor and is switched off at the latest as soon as the inner member i posltioned within the outer shell.
The method may be carried out simply because the outer shell and the inner member can be slid into the inductor from below and removed downwardly from it.

In another embodiment of the invention it is also possible to introduce the outer shell and the ceramic inner member lnto the inductor from above and to remove the composite component upwardly from the inductor or to construct the inductor so as to be movable instead of the composite components.

Exemplary embodiment~ of the invention will be apparent from the following description of the drawings. In the 2~ o~

schematic drawings:

Figure 1 shows an outer shell introduced into an inductor in a first exemplary embodiment, Figure 2 shows a gas flushing brick subsequently positioned within the outer shell, Figure 3 shows the composite component whilst being removed from the inductor, and Figure 4 shows a second exemplary embodiment.

An inductor 1 has a water-cooled coil 2 which is connected to a frequency inverter 3. This has a power of about 25kW and has a working frequency between 7kHz and lOkHz.

The inductor 1 defines an lnternal space 4 which is closed in a heat-insulating manner laterally and at its upper surface 5. The lower end of the internal space 4 can be closed by means of a flap or the like.

In the method, a frusto-conical outer shell 6 of steel plate is moved from below in the direction of the arrow A into the inductor 1 until its upper edge 7 abuts the upper surface 5 of the internal space 4. The outer shell 6 is upported at its lower edge by a divided carrler 9 whlch has a central opening 10 tsee Figure 1). The inverter 3 i~ then switched on so that current flows through the coil 2. The outer shell 6 heats up to, for instance, 800C to 950C in the alternating magnetic field of the coil 2. This temperature is reached after about 20s to 30s. During the warming the outer shell 6 expands.

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The frusto-conical gas ~lushing plug 11 of ceramic material is now pushed into the expanded outer shell 6 in the direction of the arrow A until it is in close engagement. This requires that the adjoining surfaces of the two members to be connected together have been matched to one another in a cold state as precisely as possible. Excessively large tolerances in the dimensions are as damaging as excessively large non-uniformities of the surfaces of the ad~oining members.
If necessary, assistance can be provided in this connection by machining or by other suitable means.

In order to compensate for large tolerances or large non-uniformities between the opposing surfaces of the outer shell 6 and the inner member 11, the gas flushing plug 11 in the case of the example, an intermediate layer, which is not shown in detail in the drawing, is provided. Before the assembly of the outer shell 6 in the inner member 11 this i~ either inserted into the outer shell 6 or placed on the inner member 11. During the shrinking-on process, the wall thickness of the intermediate layer deforms in accordance with the respective tolerances and/or the local non-uniformities. The intermediate layer need not wholly surround the lnner member 11. It i9 also sufficient if the intermediate layer only partially surrounds the inner member 11. The intermediate layer can be constituted by a mat or a moulded member.

The intermediate layer can comprise a compxessible fibre material. It can also comprise a material which expands under the influence of temperature. In this case the intermediate layer can be composed on the 2 ~

-lO- 23843-222 basis of ceramic fibres, preferably aluminosilicate fibres, and expandible vermiculite.

The gas flushing plug 11 is carried by a lifting device 13 which introduces it into the inductor 1. As soon as the gas flushing plug 11 is positioned in its desired composite position within the outer shell 6, the inverter 3 is switched off and the carrier 9 opened ~see Figure 2). The outer shell 6 now shrinks onto the gas flushing plug 11.

The composite component compri~lng the outer shell 6 and gas flushing plug 11 is then removed downwardly from the internal space 4 in the direction of the arrow B by means of the lifting device 13. The carrier 9 does not prevent this since it is open. The composite component can then cool down under ambient temperature.

The switching off of thefrequency inverter 3 need not necessarily only occur when the ga~ flushing plug 11 has been positioned within the outer shell 6. The frequency inverter 3 can also be switched off during the introduction of the gas flushing plug 11 since the outer shell 6 does not shrink immediately after switching off due to the heat storage capacity in con~unction with good thermal lnsulation of the inductor, which can also be matched to the shape of the workpiece.

In a further exemplary embodiment (see Figure 4), the cold ~.uter shell 6 and the gas flushing plug 11 are joined together outside the internal space 4. This can be effected by pushing the outer shell 6 onto the ~ ~ 3 ~ v~

gas flushing plug 11 which is already sitting on the lifting device 13. ~his can, however, also be effected by pushing the gas flushing plug 11 into the outer shell 6. Since the gas flushing plug 11 in this state has not yet expanded, the desired, predetermined composite position is not yet achieved in the composite component.

Subsequently, this composite component is pushed by means of the lifting device 13 in the direction of the arrow A into the internal space 4 from below until the upper edge 7 of the outer shell 6 engages the upper side 5 of the internal space 4. This position is shown in Figure 4.

Thereafter the frequency inverter 3 is switched on so that the outer shell 6 warm~ up and expands. The ga~ flushing plug 11 is then pushed further in the direction of the arrow A by means of the lifting device 13 until it is poRitioned in its composite position.
Its upper end face is deslgnated 12 in Figure 2. The frequency converter is switched off so that the outer shell 6 now shrinks onto the gas flushlng plug 11. The lifting device 13 now move~ the composite component 6,11 out of the lnternal space 4 in the directlon of the arrow B.

In a further embodiment certain features of the de3cribed embodiment~ are combined. It iq, for instance, po~sible to hold the cold outer shell 6 in the inductor 1, in accordance with Figure 1, and then to introduce the gas flushing plug 11 by means of the lifting device 13 into the outer shell 6, which is ~31~

still cold, whereby the position of Figure 4 is reached. The outer shell 6 is then heated up and the gas flushing plug 11 positioned in the manner described.

The inductor can be so arranged that it is closed at the bottom and open at the top. However, the disadvantage of this is the heat loss through the upwardly open side.

Claims (23)

1. Method of manufacturing a composite component by shrink-ing an outer shell onto a ceramic inner member wherein the outer shell is heated and finally the composite component is cooled after mutual positioning of the outer shell and the inner member, characterised in that the outer shell is heated by means of inductive heating and that thereafter the inner member is inserted into the outer shell, which is maintained at a desired temperature level, and positioned in it.

2. Method of manufacturing a composite component by shrink-ing an outer shell onto a ceramic inner member wherein the outer shell is heated and finally the composite component is cooled after mutual positioning of the outer shell and the inner member, characterised in that the inner member and the cold outer shell are assembled and the composite component is heated by means of inductive heating and that thereafter the inner member is positioned in the outer shell which is maintained at a desired temperature level.

3. Method as claimed in claim 1, characterised in that the outer shell is metallic.

4. Method as claimed in claim 2, characterised in that the outer shell is metallic.

5. Method as claimed in claim 1, characterised in that the outer shell comprises an inductively heatable ceramic material.

6. Method as claimed in claim 2, characterised in that the outer shell comprises an inductively heated ceramic material.

7. Method as claimed in any one of claims 1 to 6, charac-terised in that the ceramic inner member is plate-shaped and the outer shell is of annular strip-shape.

8. Method as claimed in any one of claims 1 to 6, charac-terised in that the outer surface of the ceramic inner member and the inner surface of the outer shell associated with it are cylin-drical, conical or frusto-conical.

9. Method as claimed in claim 1 or any one of claims 3 to 6, characterised in that the outer shell is introduced into an in-ductor connected to a frequency inverter and is heated by it to 500°C to 1000°C, preferably to 800°C to 950°C, that thereafter the ceramic inner member is introduced into the outer shell and is positioned in its predetermined composite position and that finally the frequency inverter is switched off and the composite component is removed from the inductor.

10. Method as claimed in any one of claims 2 to 6, charac-terised in that the outer shell and the ceramic inner member are assembled outside an inductor, that thereafter the composite com-ponent is introduced into the inductor, which is connected to a frequency inverter, and the outer shell is heated in it to 500°C
to 1000°C, preferably 800°C to 950°C, that the composite component is then positioned in its predetermined composite position and the frequency inverter is switched off and that the composite compon-ent is then removed from the inductor.

11. Method as claimed in claim 9, characterised in that the frequency inverter is a mean frequency inverter with a nominal power of 12kW to 30kW, preferably 25kW, and a frequency of 4kHz to 12kHz, preferably 7kHz to 10kHz.

12. Method as claimed in claim 10, characterised in that the frequency inverter is a mean frequency inverter with a nominal power of 12kW to 30kW, preferably 25kW, and a frequency of 4kHz to 12kHz, preferably 7kHz to 10kHz.

13. Method as claimed in any one of claims 1 to 6, 11 or 12, characterised in that before the positioning of the inner member in the outer shell a temperature-resistant intermediate layer is applied externally to the inner member or internally within the outer shell, the intermediate layer being deformable by manufacturing tolerances or non-uniformities between the inner member and the outer shell.

14. Method as claimed in claim 13, characterised in that the intermediate layer wholly or partially surrounds the inner member.

15. Method as claimed in claim 13, characterised in that the intermediate layer is compressable.

16. Method as claimed in claim 13, characterised in that the intermediate layer expands under the action of temperature.

17. Method as claimed in claim 16, characterised in that the intermediate layer is composed on the basis of ceramic fibres, preferably aluminosilicate fibres, and expansible vermiculite.

18. Method as claimed in any one of claims 14 to 17, charac-terised in that the intermediate layer is a mat or a moulded member.

19. Method as claimed in any one of claims 1 to 6, 11, 12 or 14 to 17, characterised in that the inner member is a gas flushing plug.

20. Method as claimed in any one of claims 1 to 6, 11, 12 or 14 to 17, characterised in that the ceramic inner member is a nozzle for metallic melts, such as a free-running nozzle, alter-nating nozzle on sliding gate valves or immersion nozzle or shadow tube.

21. Method as claimed in any one of claims 1 to 6, 11, 12 or 14 to 17, characterised in that the ceramic inner member is a par-ticle filter and/or a catalyst.

22. Method as claimed in any one of claims 1 to 6, 11, 12 or 14 to 17 characterised in that the outer shell is introduced into the inductor from below and fixed in position, the inductor is heat-insulated on all sides and is closed, that the frequency inverter is then switched on and after 10s to 60s, preferably 20s to 30s, the ceramic inner member is introduced into the outer shell and is positioned therein, that subsequently or during the introduction of the ceramic inner member the frequency inverter is switched off and finally the composite component is removed downwardly out of the inductor.

23. Method as claimed in any one of claims 1 to 6, 11, 12 or 14 to 17, characterised in that the outer shell and the ceramic inner member are introduced into the inductor from above and the finished composite component is removed upwardly from the inductor and/or that the inductor is movably constructed for the introduc-tion or removal of the components.