T 0037/85 (Pouring ladles) 13-01-1987
I. European application No. 80 100 163.7, filed on 14 January 1980, led on 22 June 1983 to the grant of European patent No. 0 017 696. Claim 1 as granted reads as follows:
1. Rotary turret for pouring ladles (12) with two opposing levers (7) of clevis design (plan view) arranged mainly symmetrically to the turret axis of rotation, each with a receiving device (11) for a pouring ladle (12) at its free end and hinged (14) to a part (3) of the turret arranged to rotate about the axis of rotation of the turret, each with a lifting device (15) connected to the turret at one end and to the lever (7) at the other, such lifting device (15) consisting in particular of an arrangement of pneumatic cylinders and pistons designed to permit limited vertical movement of the levers (7), each lever (7) having appropriate steering arms and so forming an adjustable articulated guide frame, characterized in that the two load arms (8) of the clevis-shaped lever (7) are connected by their transverse member (9) to a force arm (10) and the lever (7) is hinged in the open (plan view) bearings (14, 14') connected to the moving part of the turret or a trunnion ring (3).
II. Notice of opposition was filed requesting revocation of the patent on the grounds that its subject-matter lacked patentability. The Opposition Division rejected the opposition by decision of 4 December 1984.
III. On 19 January 1985 the opponent lodged an appeal against this decision, requesting revocation of the patent in its entirety or, failing that, oral proceedings. The grounds of appeal were received on 25 March 1985.
IV. In these grounds the appellant (opponent) cites the following documents:
DE-A-2 430 786
"Stahlstranggießanlagen", Verlag Stahl-Eisen mbH Düsseldorf 1976, page 217 DE-B-2 044 979 DE-A-2 744 670 DE-A-2 425 053.
V. He argues that Claim 1 is not limited to either a single force arm for each clevis lever or to a two-armed lever (the features the Opposition Division focussed on when considering inventive step), and that the invention is not patentable vis-à-vis the above prior art. He also doubts whether the invention overcomes the disadvantages of the prior art.
VI. At the oral proceedings on 13 January 1987 the patent proprietor submitted new Claims 1-8 clarifying and replacing those granted. Claim 1 as thus amended reads as follows:
1. Rotary turret for pouring ladles (12) with two opposed (in plain view) clevis levers (7) essentially arranged symmetrically to the turret axis, each with a receiving device (11) for a pouring ladle (12) at the free end and hinged (14) rotatably to a moving part (3) of the turret at the axis of rotation, with at least one articulated lifting device (15) connected to the turret at one end and to the lever (7) at the other, the said lifting device (15) consisting essentially of pneumatic cylinders and pistons in an assembly designed to permit limited vertical movement of the levers (7), each featuring appropriate steering arms and thus forming an adjustable articulated guide frame, characterized by: the two load arms (8) of the clevis lever (7) being connected by their cross member (9) to a single force arm (10) and the two-armed lever (7) tiltably carried in the (plan view) open bearings (14 and 14') connected to the moving part of the turret, e.a. at a trunnion ring (3). The patent proprietor contests the appellant's submissions on all points, and requests that the appeal be dismissed and the patent maintained with the claims submitted at the oral proceedings. The appellant reaffirms his position, adding that it is not clear what is meant by a "two-armed lever". He maintains his request that the patent be revoked in its entirety.
1.The appeal complies with Articles 106 to 108 EPC and is therefore admissible.
2. There can be no formal objection to the wording of the amended claims, this being sufficiently supported by the description as originally filed. Claim 1 as originally filed was in fact limited to a double-armed lever in the (plan view) open bearings, and original Claim 2 to a single force arm. The amendments to Claim 1 represent clarifications: the term "two-armed" now employed merely clarifies the original wording "double-armed" in respect of the invention described. With two-armed levers too the forces are applied on both sides of the fulcrum.
3. Examination of whether a device according to Claim 1 is disclosed in the documents cited in the grant and opposition proceedings shows that the subject-matter of Claim 1 is new vis-à-vis the prior art. Nor has the appellant disputed such novelty.
4. The question is therefore whether the device involves an inventive step. This can be answered as follows:
4.1 The Board sees no objection to the preamble of Claim 1. Its wording is based on DE-A-2 430 786. This known device has two opposed pairs of one-armed clevis levers. One end of each pair of levers is hinged to the main column of the rotary turret on a horizontal axis, whilst the other end has a receiving device for the pouring ladle. The levers are raised and lowered by means of pneumatic cylinder and piston assemblies connected at one end to the column and at the other to the lever. The appellant argues that the load arm, cross-member and force arm constitute a single rigid component, i.e. that these arms and the cross-member are all fixed together. The Board does not agree. It is not clear from DE-A-2 430 786 whether the pairs of levers are fixed together or completely independent of each other. The description in the citation states (page 8, paragraph 4) that the head of the turret has two horizontal axles arranged symmetrically to the common vertical axis and around which the two clevis lever arms are hinged. There is no mention here of a continued possible transfer of torque from one arm to the other. Page 9, paragraph 1 of the same description adds that all four connecting rods are hinged around a common axle. In other words, they are described in exactly the same terms as the lever arms. But here it is clear that no transfer of torque can occur, because the connecting rods rotate in opposing directions. The Board is therefore of the opinion that it is not possible to establish from this citation whether or not the two pairs of levers are fixed together, and so there is no objection to the characterising portion of Claim 1.
4.2 The Board agrees with the patent proprietor that with known rotary turrets the levers bearing significant load are mounted in solid axles. These axles and their precision bearings are subject to considerable wear at high loads. Exposing the bearings is awkward and there is a danger of edge pressure in the event of deformation, elongation or imprecision during manufacture of the bearing mounting. Lack of space also makes access to the bearings for inspection or maintenance purposes very difficult.
4.3 On the basis of the prior art contained in DE-A-2 430 786, the problem the invention seeks to solve (cf. column 2 of European patent 0 017 696) is to devise a rotary turret without such disadvantages and permitting easier assembly and servicing.
4.4 The solution found in the present patent consists in tiltably carrying the two-armed lever comprising a rigid componentmade up of load arms, a single force arm and a transverse member, in (plan view) open bearings, as explained in greater detail in the characterising part of Claim 1.
4.5 Neither DE-A-2 430 786 nor any of the other prior art suggests the solution adopted in Claim 1. DE-A-2 744 670 and DE-A-2 425 053 do not contain any of the characterising features of Claim 1. Bearings open at the top are usual in continuous steel- casting installations (cf. page 217 of German work entitled "Strahlstranggießanlagen") and have also been used in rotary turrets for casting installations (cf. DE-B-2 044 979). However, the former citation describes a stationary receiving system for a distribution vessel, in which the hinge axle axis and pneumatic cylinder of a casting vessel are supported in bearing shells open on one side. The Board therefore takes the view that this solution does not lead the skilled man towards the claim at issue. The rotary turret for pouring ladles known from DE-B-2 044 979 is acknowledged in the introduction to the description of the patent (cf. column 1, lines 24 to 38). It has only a single arm, hinged on a rotating bearing block. On each side of the hinge are lifting means with concave surfaces at both ends and bearings to fit. From this bearing system - and even if the open-topped bearing were to be moved in the rotating turret from the lifting device to the tilt axle - the skilled man could not arrive at the turret in accordance with Claim 1. Among other things, the two independent levers are missing. The Board considers that the inventive step lies in the combination of a two-armed lever plus single force arm with a bearing open in plan view. It does not matter whether individual features are entirely or at least partly known: a combination invention means looking at the features as a whole. One cannot do justice to a combination invention by comparing every individual feature with the prior art; the fact that individual or several features are known or obvious does not necessarily mean that the claimed combination is anticipated or obvious. With combination patents the question is whether the prior art suggests combining all the features, bearing in mind their functions within that combination. In answering it, it is irrelevant whether the features of the combination are already known individually.
4.6 For these reasons, the prior art in question would not have enabled the skilled person to arrive in an obvious way at the subject-matter of Claim 1.
5. Claim 1 thus involves an inventive step within the meaning of Article 56 EPC.
6. Claims 2 to 7 are dependent upon Claim 1 and relate to specific embodiments of the invention according to Claim 1. They are thus also allowable.
7. The appellant doubts whether the disadvantages in the prior art are overcome by the design according to the patent, and argues that inspection and maintenance of the bearings are certainly not disadvantageous in the known design. The patent proprietor plausibly replies that the levers are hinged on a part of the turret rotatable around the axis of the rotary turret, and moreover are fixed at a point on the single force arm to a lifting device. However, a bearing is subject not only to static load (weight) but also to the load caused by mechanical and thermal movement (deformation) of the lever. The present invention uses concave surfaces to increase the service life of the lever bearing system, and it remains extremely important for maintenance purposes that exact information be available on the state of wear of individual components, to keep them in use and reduce breakdown. In the present case the lever could be lifted by crane to expose the bearing system quickly and simply for inspection. This would enable damage to be detected at an early stage, avoid unnecessary repair work and increase overall reliability.
For these reasons, it is decided that:
1. The appeal is rejected.
2. The case is remitted to the first instance to maintain the European patent in the amended form submitted at the oral proceedings.