T 0342/03 05-10-2005

I. The applicant lodged an appeal against the decision of the Examining Division to refuse the European patent application No. 98 110 006.8.

The Examining Division held that claims 1 and 13 as filed on 29 May 1999 met the requirements of Article 123(2) EPC but that the subject-matter of these claims lacked an inventive step over document D2 (= US-A-2 756 169).

II. With a communication dated 4 July 2005 and annexed to the summons to oral proceedings the Board presented its preliminary opinion with respect to claims 1, 2 and 13 as filed together with the grounds of appeal on 28 February 2003. The subject-matter of the process claims 1 and 2 and of the device claim 13 was considered to lack inventive step over the disclosure of D2 and the common general knowledge of the skilled person.

III. In response to this communication the appellant filed with its letter of 30 August 2005 a new request comprising claims 1 to 10 and further arguments in order to support inventive step of the subject-matter claimed.

IV. Oral proceedings before the Board of Appeal were held on 5 October 2005.

The appellant requested that the decision under appeal be set aside and a patent be granted on the basis of claims 1 to 10 according to the main request as submitted with letter of 30 August 2005, or alternatively on the basis of these claims, amended according to two subsidiary requests.

V. Independent claims 1, 2 and 10 of the main request read as follows:

"1. Method for heat treating a first and a second class of rolled stock (13) leaving a rolling train (12), wherein said first class of rolled stock (13) is subjected to a treatment of surface hardening, while said second class of rolled stock (13) is subjected to a controlled cooling in order not to obtain hardened structures, said method comprising a rapid cooling step for rapidly cooling said rolling stock (13) in a rapid cooling assembly (11) located immediately downstream of the last rolling pass to quickly reduce the temperature of the surface of said rolled stock (13), a temperature-equalisation step in air and at least a second cooling step before discharging and wound said rolled stock (13) into coils on a winding assembly (16), the method being characterised in that, for said first class of rolled stock (13),

- said rapid cooling step rapidly decreases the temperature of the surface of said rolled stock (13) below the point of martensitic transformation and causes the formation of a martensitic surface structure, a bainitic sub-surface structure and a pearlitic inner structure,

- said temperature-equalisation step in air is performed in a first segment (14) wherein the progressive propagation of the heat from the core to the periphery of the rolled stock (13) causes the tempering of the martensitic structures obtained in the surface areas of the rolled stock (13),

- the tempering of said rolled stock (13) is stopped in said second cooling step so that the martensitic structures which have formed on the surface of the rolled stock (13) are not modified,

- said at least second cooling step is set so as not to modify the surface crystalline structure and the inner crystalline structure of the rolled stock (13) which have formed at the outlet of said rapid cooling treatment, to prevent the depth of the martensitic surface layer from increasing and to avoid the need of a further cooling step of said coils,

- said at least second cooling step is followed by a segment of temperature-equalisation in air, shorter than said first segment (14), so as to achieve the optimum winding temperature and

- said rolled stock (13) is then directly wound into coils on said winding assembly (16), whereby the slow cooling of the rolled stock (13) wound in compact form on said winding assembly (16) completes the tempering of the hardened outer crown, previously interrupted, in an optimum manner and leads to the transformation of the crystalline structure in the stable structures."

"2. Method for heat treating a first and a second class of rolled stock (13) leaving a rolling train (12), wherein said first class of rolled stock (13) is subjected to a treatment of surface hardening, while said second class of rolled stock (13) is subjected to a controlled cooling in order not to obtain hardened structures, said method comprising a rapid cooling step for rapidly cooling said rolling stock (13) in a rapid cooling assembly (11) located immediately downstream of the last rolling pass to quickly reduce the temperature of the surface of said rolled stock (13), a temperature-equalisation step in air and at least a second cooling step before discharging and wound said rolled stock (13) into coils on a winding assembly (16), the method being characterised in that, for said second class of rolled stock (13),

- said rapid cooling step rapidly decreases the temperature of the surface of said rolled stock (13) above the point of martensitic transformation, so that the substantially homogeneous austenitic structure is not transformed;

- said temperature-equalisation step in air is performed in a first segment (14) wherein the equalisation of the temperature of the core and the surface of said rolled stock (13) occurs,

- said at least second cooling step is regulated, in terms of duration and intensity of cooling, in such a way that the surface temperature of the rolled stock (13) is not taken below the level at which bainite forms, whereby said at least second cooling step avoids the need of a further cooling step of said coils,

- said at least second cooling step is followed by a segment of temperature-equalisation in air, shorter than said first segment (14), so as to achieve the optimum winding temperature, and

- said rolled stock (13) is then directly wound into coils on said winding assembly (16), whereby the slow cooling of the rolled stock (13) wound in compact form on said winding assembly (16) leads to the transformation of the austenite in the stable structures."

"10. Device for heat treating a first and a second class of rolled stock (13) leaving a rolling train (12) having a last rolling pass, wherein said first class of rolled stock (13) is subjected to a treatment of surface hardening, while said second class of rolled stock (13) is subjected to a controlled cooling in order not to obtain hardened structures, said device being characterised in that it comprises a rapid cooling assembly (11) located immediately downstream of said last rolling pass and able both to cause in said first class of rolled stock (13) the formation of a martensitic surface structure, a bainitic sub-surface structure and a pearlitic inner structure and to cool said second class of rolled stock (13) at a speed above the critical speed and to take the surface temperature of said second class of rolled stock (13) to a value not less than the level at which martensite forms, in that said rapid cooling assembly (11) is followed by a first segment (14) of temperature-equalisation in air, which is followed by one to four cooling stages (15a, 15b, 15c), in that each of said cooling stages (15a, 15b, 15c) is set in such a way as not to modify the crystalline surface structure which has formed at the outlet of said rapid cooling assembly (11) which remains mostly unchanged, in that each of said cooling stages (15a, 15b, 15c) is followed by a corresponding segment of temperature-equalisation in air shorter than said first segment (14), and in that a winding assembly (16) is provided immediately downstream said cooling stages (15a, 15b, 15c) for the direct winding of the rolled stock (13) into coils of compact spirals".

VI. The first auxiliary request comprises

- claim 1, lines 9 to 12 reading "followed by a brief segment of temperature-equalisation in air, so as to achieve the optimum winding temperature and"

- claim 2, lines 26 to 28 reading: "followed by a brief segment of temperature-equalisation in air, so as to achieve the optimum winding temperature and"

- claim 10, lines 18 to 20 reading: "(15a, 15b, 15c) is followed by a brief segment of temperature-equalisation in air, and in that a winding assembly".

VII. The second auxiliary request comprises

- claim 1 amended as per first auxiliary request, the last part now reading: "so as to achieve a winding temperature of between 420ºC and 570ºC and"

- claim 2 as amended per the first auxiliary request, the last part now reading: "so as to achieve a winding temperature of between 650ºC and 750ºC and".

VIII. The appellant argued essentially as follows:

The claimed feature "followed by a (corresponding) segment of temperature-equalisation in air shorter than said first segment (14)" can be derived from figure 1 of the specification as originally filed which clearly shows that the distance of the first segment (14) is shorter than those of the segments following the intermediate cooling stages (15a, 15b, 15c). Another basis for this amendment can be found at e.g. page 7, line 18 or page 12, lines 7 to 22 of the application as originally filed where "a brief segment of temperature-equalisation in air" is mentioned; or at page 14, lines 10 to 21 where "short temperature-equalisation segments" or "short equalisation segments" are mentioned. The different distances allow to cool down the rolled stock faster and thus to avoid the overtempering during the winding of the stock at a preset temperature without changing the previously formed structure. Therefore this amendment meets the requirements of Article 123(2) EPC.

A basis for the amendment "a brief segment" according to the auxiliary requests can be found at e.g. page 7, line 18; page 12, lines 7 to 22; and page 14, lines 10 to 21 of the application as originally filed. From figures 2 and 3 it can be derived that the terms "short" or "brief" mean a length of about 20 meters. The description does not give a more precise definition of the relative distances but the resulting effect is described in more detail. The generalisation to "at least one second cooling step" - which implies "at least one brief segment of temperature equalisation in air" following the second cooling step is supported by the disclosure at page 7, lines 18 to 20; page 7, line 31 to page 8, line 1; and page 12, lines 7 to 22 of the application as originally filed, so that the requirements of Article 123(2) EPC should be met.