T 2187/14 19-04-2018

Reasons for the Decision

1. Consideration of late-filed documents (Articles 12(4), 13 RPBA)

1.1 Documents E4* and E10 to E14* were filed for the first time with the opponent's grounds of appeal. Therefore, it is necessary to assess whether they should have been submitted earlier (Article 12(4) RPBA).

1.2 E4* is a response to the opposition division's interpretation of the term "Erstarrung" given in the decision under appeal. Thus, it has been filed at the earliest possible point in time, and as such can be taken into consideration, particularly since this is an important aspect when considering the content of E3.

1.3 E10* is a barely understandable machine translation of E10. E10** is a second and allegedly improved machine translation submitted in response to the Board's criticism of E10*. However, the Board does not see it as appropriate to allow a party to file numerous machine translations throughout the procedure until it comes up with one that conveys the nuance that supports its case. A certified translation should have been filed at the earliest opportunity. Therefore, these documents will be considered only to the extent that they might help in understanding the figures of E10.

1.4 E11, E12 and E13 have been cited to support alternative attacks on inventive step which should have been made before the opposition division; therefore these documents will not be taken into consideration.

1.5 E14, together with the English translation E14*, are very relevant to the question of novelty (see below) of the amended apparatus claim 27 filed during the oral proceedings before the opposition division. Since these documents were filed at the earliest opportunity and are relevant, the Board will take them into consideration.

1.6 References to E15 were submitted after the grounds of appeal were filed. Further, since E15 was only cited as evidence that a meniscus is present on the upper surface of the molten metal which is no longer a subject of debate in the proceedings, it will not be taken into consideration.

1.7 The opposition division did not admit E7 into the proceedings since it only concerns an apparatus for determining the surface level of molten metal in casting processes. The Board considers the opposition division exercised its discretion correctly and will not take E7 into consideration.

2. Article 100(b) EPC, sufficiency of disclosure

2.1 The opposition division decided not to admit this ground of opposition into the proceedings since it was filed after expiry of the opposition period and was not on the face of it prejudicial to the maintenance of the patent.

2.2 The opponent's submissions during the opposition proceedings made in its letter of 27 January 2014,(see page 8) and during the oral proceedings (see the minutes page 3, item 6) were limited to the feasibility of adjusting the temperature of the divider wall. The opposition division considered that the skilled person would know how to adjust the temperature of the divider wall, and therefore, that the ground was not prima facie relevant.

2.3 During the appeal proceedings, the opponent submitted that the "self-supporting" surface could not be achieved over the whole range between the solidus and liquidus temperatures. However, this had not been argued during the opposition proceedings. Therefore, this is not an argument showing that the opposition division erred in its discretionary decision and that this opposition ground should have been admitted into the proceedings, but rather a new line of argument to support a ground that is not in the proceedings.

2.4 In conclusion, the opposition division exercised its discretion correctly under Article 114(2) EPC since it fully took into account arguments submitted by the opponent at that stage of the proceedings.

2.5 Since the patent proprietor has not given its consent for this ground of opposition to be admitted into the proceedings, the Board is not in a position to consider the matter any further (see G10/91, Headnote, paragraph 3).

3. Article 123(2) EPC, extended subject-matter

3.1 The opponent made no objections under Article 123(2) EPC with respect to claims 1 and 27 of the version which the opposition division considered could be maintained.

4. Claim 1, Novelty

4.1 With respect to the disclosure of E3

4.1.1 There is no explicit mention in E3 of either of the first alloy pool forming a "self-supporting" surface or of contact of the second alloy pool with this self-supporting surface at a point where the temperature of the self-supporting surface is between the solidus and liquidus temperatures of the first alloy. Therefore, it must be assessed whether these features are unambiguously and directly disclosed.

4.1.2 The Board agrees with the patent proprietor that in the first embodiment of E3, illustrated in figures 1 to 3, features 1c and 1d of claim 1 are not realised, since an open-ended mould is not provided and an ingot cannot be extracted from the exit end.

4.1.3 In the arrangements shown in figures 1 to 3, in order that the alloy forming the cladding plates undergoes a certain pre-solidification ("gewisse Vorestarrung" see page 2, lines 105 to 107) before coming into contact with the core alloy, the side-walls of the lower container 7 are provided with extensions 9 which are long enough to ensure that the cladding alloy is "bereits in Erstarrung begriffen" (see page 2, lines 108 to 113) before contact. The Board understands this expression to mean that solidification of the cladding alloy is in progress, but not completed.

4.1.4 In both of the embodiments illustrated in figures 4 and 5 of E3, the molten core surface is always below the already cooled cladding alloy such that a self-supporting surface is not formed on the side of a molten core pool since it will always be supported by the cladding alloy. Therefore, the situation in figures 4 and 5 corresponds to that shown in figure 4 of the contested patent which is no longer part of the invention.

4.1.5 The embodiments shown in figures 4 and 5 of E3 are provided with various arrangements and geometries of cooling members 15, 16; 20, 21. These cooling members are positioned directly below the crucibles 12; 19 respectively containing the molten cladding alloy in each embodiment.

4.1.6 The additional presence of these cooling members indicates that the intention is to ensure that solidification of the cladding alloy is accelerated. This would seem particularly so in the apparatus of figure 5 where the cladding alloy is placed between two cooling members of either circular (20) or rectangular (21) cross-section such that the cladding alloy solidifies ( "die Plattierschmelze erstarrt" - see page 3, line 25).

4.1.7 This supports the patent-proprietor's submission that in all the embodiments of E3 emphasis is placed on the necessity for the cladding alloy to be already solidified before contact with the core alloy.

4.1.8 With reference to the embodiment of figure 5 of E3, this is borne out by the passage on page 3, lines 26 to 28 stating:

"The core alloy material only flows out the floor of chamber 18 once an already solidified cladding alloy is present" ("Die Kernstoffschmelze tritt aus dem Boden, der Kammer 18 erst aus, wenn die bereits erstarrten Plattierschichten vorliegen").

4.1.9 The expression "bereits in Erstarrung begriffen ist" (see page 3, lines 9 to 11), used in connection with the apparatus of figures 1 to 3, is again employed to describe the situation in the case of the apparatus shown in figure 4. This expression needs to be seen in its full context of:

"Auch bei dieser Ausführung ist sichergestellt, daß die Plattierschmelze bereits in Erstarrung begriffen ist" ("Also in this embodiment it is ensured that solidification of the cladding alloy has started/is in progress").

4.1.10 It is evident from figure 4 of E3 that solidification of the cladding alloy will commence on the side which is in contact with the cooling member, and lower down makes contact with the molten core material (in a similar fashion to that shown in figure 4 of the patent). In the context of the patent, the skilled person would understand the above expression to mean that whilst the cladding alloy might not be completely solidified across its whole section, it must be ensured that at least the side contacting the core alloy is. This interpretation is not in contradiction with the definition of "Erstarrung" given in E4* which confirms that solidification usually takes place from the outside to the inside of an ingot since cooling takes place at the outside surface.

4.1.11 The opponent's assertion that the dashed lines in figure 4 indicate that the cladding has not completely solidified and therefore the surface contacting the molten core alloy must be in the mushy state is not persuasive. The figures of a patent document are purely schematic and any attempt to identify specific boundaries between molten, semi-solid and solid states on the basis of approximately applied dashed lines is not possible.

4.1.12 In conclusion, feature 1ib is not directly and unambiguously disclosed in E3.

4.2 With respect to the disclosure of E5

4.2.1 As regards E5, it is apparent from figures 1, 1A and 3 that the contact point of the alloys 18" and 19' lies well below the solidus line or solidification level S of the alloy 18". The critical indication in the description is the passage from column 6, line 68 to column 7, line 3 which states:

"Thus, by the time the molten metal material 19 for the core 19' makes contact at about level X with the combined cladding and tubular mold 18', mold 18" will be a strong solid impervious structure."

4.2.2 The Board does not accept the opponent's assertion that it is clear from the description at column 6, lines 43 to 57, that the alloy 18" can also be in the mushy zone. Figure 1A leaves no doubt as to when solidification occurs and indicates that both the solidus line S and the initial freezing level or liquidus level F lies well above the contact point X with the molten core.

4.2.3 Similarly for the apparatus illustrated in figure 1D, it is ensured that:

"in any event, the metal 18' forming cladding 18'' will still be substantially fully solidified across its width or for its full thickness as it clears the bottom 37 of baffle 14' at about level 38 and prior to contact with the molten core metal 19' containing lithium"

4.2.4 Thus, similarly to E3, the emphasis in the methods disclosed in E5 is to ensure that the cladding alloy is solidified before contact with the molten core such that the molten core is poured into and contained by the surrounding cladding.

Thus, feature 1ib is also not disclosed in E5.

4.3 With respect to the disclosure of E8

4.3.1 As pointed out by the patent proprietor, Figure 921 and the related text of E8 correspond to figure 5 and text of E3, thus, the same arguments apply.

In conclusion, the subject-matter of claim 1 is new with respect to E3, E5 and E8 and therefore meets the requirements of Article 54 EPC.

5. Claim 27, Novelty

Novelty of the subject-matter of claim 27 was not contested by the opponent.

6. Claim 1, Inventive step

6.1 When account is taken of the fact that E11, E12 and E13 will not be taken into consideration under Article 12(4) RPBA, the following attacks against inventive step remain:

E3 in combination with:

(i) the skilled person's general knowledge; or

(ii) E9 (see in particular column 3, lines 59 to 62 and figure); or

(iii) E10; or

(iv) E6

6.2 As reasoned above when examining novelty, the subject-matter of claim 1 differs from the method known from E3 by feature 1ib:

- allowing the second alloy pool to contact the first alloy pool such that the upper surface of the second alloy pool contacts the self-supporting surface of the first alloy pool at a point where the temperature of the self-supporting surface is between the solidus and liquidus temperatures of the first alloy.

6.3 The technical effect of this feature is to improve the bond between the two alloys of the composite ingot.

The objective technical problem can therefore be defined as one of providing an improved connection between the cladding and the core.

6.4 E3 in combination with the skilled person's general knowledge

6.4.1 The Board does not accept the opponent's submission that since E3 indicates that the solution to overcome the problems associated with contacting two molten alloys (see page 1, lines 20 to 29) when casting a composite ingot, is to pre-solidify the cladding alloy, the skilled person would immediately understand from E3 that it was sufficient to cool the cladding alloy such that it was not in a liquid state, but not necessarily completely solidified. As already discussed in relation to novelty, the constant emphasis in E3 is to ensure that the portion of the cladding alloy contacting the molten core alloy is solidified.

6.4.2 As the patent-proprietor has argued, the presence of a self-supporting surface between the solidus and liquidus temperatures is not a trivial feature, and in order to achieve one the skilled person would have to provide the apparatus of E3 with the appropriate cooling control systems, as opposed to just simply ensuring that enough cooling is provided to ensure that the cladding material is solidified at the contact point.

6.5 E3 in combination with E9

6.5.1 E9 discloses a method for casting a composite ingot in which two alloys 26 and 30 are separated by a divider wall 16 and brought together when both are in the mushy state at point 18 (see column 2, lines 68 to column 3, line 6). However, E9 fails to disclose a self-supporting surface in the mushy state, since the alloy surfaces at the contact point 18 are mutually supporting and the exterior surfaces of the alloys are contained within the mould shell 2. E9 also relates to the contact of two mushy surfaces rather than a molten pool with a self-supporting mushy surface.

6.5.2 Therefore, the teachings of E9 would not lead the skilled person seeking a solution to the above problem to modify the method of E3 in order to arrive at the subject-matter of claim 1 in an obvious manner.

6.6 E3 in combination with E10

6.6.1 From the figures of E10 it is apparent that an alloy sheet 21 is pressed by cooling rollers 5A, 5B onto a second alloy 11A which has a molten core 11. Therefore, E10 concerns a process in which an alloy in a solid state is initially contacted with a molten alloy and which is subjected to constant pressure. Consequently, there is no suggestion of providing a self-supporting surface in the mushy state which is contacted by a molten alloy since the process relies on the pressure applied.

6.7 E6 in combination with E3

6.7.1 In the method disclosed in E6, the temperature of the self-supporting surface at the contact point is not between the solidus and liquidus lines since solidification has taken place (see page 2, lines 34 to 37 and lines 107 to 114). The essential idea behind the method according to E6 is to avoid oxidation of the surfaces by bringing the first molten alloy into contact with the second molten alloy as soon as this has solidified. There is no suggestion that this should occur when the second alloy is in the mushy state.

Therefore, a combination of E6 with E3 would also not lead to the subject-matter of claim 1.

7. Claim 27, Inventive step

7.1 A suitable starting point for the assessment of inventive step is either of the devices disclosed in E5 or E14. It is common ground between the parties that neither of these documents discloses the feature of claim 27 according to which:

"a temperature measuring device (40) is provided at the fluid outlet (37)."

7.2 Contrary to the opinion of the opponent this feature does have a technical effect as explained in paragraph [0080] of the patent which states:

"It has been found in particular that at a fixed coolant flow through the channel 33, the temperature of the coolant exiting the divider wall coolant channel measured at the outlet 37 correlates well with the temperature of the self supporting surface of the metal at predetermined locations below the bottom edge of the divider wall, and hence provides for a simple and effective means of controlling this critical temperature by providing a temperature measuring device such as a thermocouple or thermistor 40 in the outlet of the coolant channel."

7.3 Further, as the patent-proprietor pointed out in the oral proceedings, measurement of the coolant outlet temperature is also advantageous in that it is less prone to oscillations caused by local mould conditions and correlates with the global average temperature of the divider wall, as opposed to a punctual value which would be provided by a thermocouple fixed to the divider wall.

7.4 The objective technical problem can therefore be seen as one of providing a casting apparatus which can be reliably controlled to provide an improved connection between the cladding and the core.

7.5 There is no hint in any of the available prior art documents or accepted general knowledge which would prompt the skilled person faced with this problem to modify the apparatus of E5 or E14 by introducing this feature.

7.6 In the embodiment shown in figure 1 of E5, the water jacket 17', comprising chamber 26, separates the molten cladding alloy from the refractory lining 23 surrounding the pouring spout 34 for the molten core alloy. Coolant can enter and exit from chamber 26 by way of passages 23' or piping in lining 23 and acts to cool the interior of jacket and mould assembly 14 (see column 6, lines 11 to 15). Cooling is also carried out by spraying water from spray-box 30 around the outside of the mould assembly (see column 6, lines 18 to 27).

7.7 Since cooling is carried out by a combination of water circulating in the chamber 26 and by spraying, the skilled person would realise that the intention in E5 is simply to provide sufficient cooling to ensure solidification of the cladding alloy before contact with molten core. In view of this, there is no incentive for the skilled person to modify the apparatus of E5 by measuring the outlet temperature of the water flowing through chamber 26 since this would only provide information on part of the cooling system and would serve no clearly useful purpose.

7.8 As regards E14, the divider wall ("partition 2") is cooled by running water (see E14*, page 4, line 25). The thermocouples 5 and 6 placed in the inclined surfaces 3 and 4 of the partition 2 measure the surface temperature of the inclined shells 8 and 9 of the two alloys being cast (see page 5, lines 16 to 17). The difference in temperature values (delta t1) obtained is used to calculate the distance l1 corresponding to the length which the non-inclined portion of the partition wall is set at for various casting processes.

7.9 There is no deliberate control of the temperature of the partition 2 which is simply cooled. Since it is the temperature difference delta t1 between the two shells being cast which is the important parameter for the process of E14, there is no incentive for the skilled person to modify the apparatus by measuring the temperature at the outlet of the cooling water running through the partition 2 instead of on the inclined surfaces 3 and 4 because this value would serve no purpose.

7.10 In conclusion, taking either E5 or E14 as the most realistic starting point, the subject-matter of claim 27 in the version the opposition division considered could be maintained involves an inventive step and meets the requirements of Article 56 EPC.