"1. A metal cutting tool (10) comprising an indexable cutting insert (12), comprising two opposing side surfaces (24), and a peripheral edge surface (26) extending therebetween and having an insert axis (a) of rotational symmetry passing through the side surfaces (24); the peripheral edge surface (26) having a plurality of abutment sections (28, 28, 28"), each abutment section (28, 28, 28") lying on a portion of a side wall (34) of an imaginary regular polygon (36) having a plurality of side walls (34), a plurality of cutting portions (32) extending outwardly from the imaginary polygon (36), the plurality of cutting portions (32) being equal in number to the number of side walls (34) of the imaginary polygon (36), each cutting portion (32) having a cutting edge (38), wherein the cutting edge (38) is formed at the intersection of a rake surface (40) and a relief surface (42), and wherein the rake and relief surfaces (40, 42) are located on the peripheral edge surface (26), each abutment section (28, 28, 28") being located between two cutting portions (32); and an insert holder (14) comprising an insert pocket (16, 16, 16") comprising a base surface (18), the cutting insert (12) is retained with the peripheral edge surface (26) being abutted at two abutment sections (28, 28") only, the insert pocket (16, 16, 16") comprising a lower support wall (20) abutting a first abutment section (28), and an upper support wall (22) abutting a second abutment section (28"); the lower support wall (20) and the upper support wall (22) each being fixed and integral parts of the insert holder (14), characterized in that the upper support wall (22) and the lower support wall (20) are straight, and define an acute angle (alpha) between them, and wherein lower support wall (20) extends generally uprightly from the base surface (18), and wherein upper support wall (22) also extends generally uprightly from the base surface (18)."
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"1. A metal cutting tool (10) comprising an indexable cutting insert (12), comprising two opposing side surfaces (24), and a peripheral edge surface (26) extending therebetween and having an insert axis (a) of rotational symmetry passing through the side surfaces (24); the peripheral edge surface (26) having a plurality of abutment sections (28, 28, 28"), each abutment section (28, 28, 28") lying on a portion of a side wall (34) of an imaginary regular polygon (36) having a plurality of side walls (34), a plurality of cutting portions (32) extending outwardly from the imaginary polygon (36), the plurality of cutting portions (32) being equal in number to the number of side walls (34) of the imaginary polygon (36), each cutting portion (32) having a cutting edge (38), wherein the cutting edge (38) is formed at the intersection of a rake surface (40) and a relief surface (42), and wherein the rake and relief surfaces (40, 42) are located on the peripheral edge surface (26), each abutment section (28, 28, 28") being located between two cutting portions (32); and an insert holder (14) comprising an insert pocket (16, 16, 16") comprising a base surface (18), the insert pocket (16, 16, 16") comprising a lower support wall (20) abutting a first abutment section (28), and an upper support wall (22) abutting a second abutment section (28"); the lower support wall (20) and the upper support wall (22) each being fixed and integral parts of the insert holder (14), the upper support wall (22) and the lower support wall (20) are straight, and wherein the lower support wall (20) extends generally uprightly from the base surface (18), and wherein the upper support wall (22) also extends generally uprightly from the base surface (18), characterized in that, the cutting insert (12) is retained with the peripheral edge surface (26) being abutted at two abutment sections (28, 28") only, wherein the upper support wall (22) and the lower support wall (20) define an acute angle (alpha) of 36º between them."
The feature of claim 1 as granted according to which the upper and lower support walls were straight was clearly and unambiguously derivable from the application as filed. Basis for this feature were the figures and the disclosure of the abutment sections of the insert lying on a portion of a side wall of an imaginary regular pentagon. Since these abutment sections contacted the upper and lower support walls of the insert pocket, the support walls also had to be straight. Compared to claim 1 as granted, claim 1 according to the main request included the additional limitation of originally filed claim 13 that the upper and lower support walls extended generally uprightly from the base surface. With this amendment it was clear that claim 1 was limited to planar upper and lower walls, and that these walls were essentially perpendicular to the base surface. Originally filed claim 13 comprised the further feature that the base surface was abutted by a given protruding polygon of the cutting insert. It was clear for the skilled person that this feature was not functionally or structurally linked to the feature that the upper and lower support walls extended generally uprightly from the base surface. Accordingly, the latter feature could be isolated from the combination of originally filed claim 13 without contravening the requirements of Article 123(2) EPC. Claim 1 according to the main request was amended over claim 1 as granted also by reciting that the cutting edge was formed at the intersection of a rake surface and a relief surface that were both located on the peripheral edge surface of the insert. This wording referred to a structural feature of the tool: it specified that the cutting edge extended over the peripheral edge surface of the insert. Although describing in detail a grooving tool having a cutting edge parallel to the axis of the insert, the application as filed was not so limited. It disclosed that the invention could be applied to suit various applications such as turning and threading operations. Cutting inserts used for these operations had cutting edges that were not parallel to the axis of the insert. Therefore, the amendments made to claim 1 in accordance with the main request met the requirements of Article 123(2) and 84 EPC.
Document D5 disclosed a cutting tool comprising an insert holder and a cutting insert held in an insert pocket of the insert holder. Two peripheral abutment sections of the cutting insert were abutted at two positioning surfaces of the insert pocket. The cutting insert was pressed against them by a clamp acting on a third peripheral abutment section. Accordingly, D5 did not disclose the feature of claim 1 that the cutting insert was retained with the peripheral edge surface being abutted at two abutment sections only. There was no indication in the prior art that would prompt a person skilled in the art to dispense with the clamp. The clamp was described in D5 as essential for maintaining the precise positioning of the cutting insert. The skilled person would also not consider abandoning the feature relating to the clamp in the embodiment according to Fig. 11 where a triangular cutting insert was used. In this embodiment, the chips cut from the workpiece flowed along the abutment section of the insert on which acted the clamp. D5 taught that chip flow occurred only over a limited portion of the abutment section, and therefore the skilled person would provide a clamp of sufficiently small size such that it did not interfere with chip flow. Therefore, the subject-matter of claim 1 according to the main request was not rendered obvious by the available prior art.
Claim 1 according to the main request introduced subject-matter extending beyond the content of the application as filed because the latter did not mention that the upper and lower support walls were straight. Nor did it disclose that these walls were planar. Furthermore, the feature added to claim 1, according to which the lower and upper support walls extended generally uprightly from the base surface, was only disclosed in combination with the feature that the base surface was abutted by a protruding polygon of the cutting insert. Also, the other feature added to claim 1, according to which the cutting edge was formed at the intersection of a rake surface and a relief surface located on the peripheral edge surface of the cutting insert, was only disclosed in combination with a specific orientation of the cutting edge, parallel to the insert axis, which was not recited in claim 1. This feature also introduced a lack of clarity because it did not define structural features of the insert but related to a possible use thereof. In fact, whether an edge was a cutting edge or not depended on the direction of feed of the tool. Furthermore, it was not clear what was meant by a wall extending "generally" uprightly.
The subject-matter of claim 1 was not novel over the disclosure of documents D5 and D6. In any case, it did not involve an inventive step when starting from document D5, assuming that this document did not disclose the feature of claim 1 according to which the cutting insert was retained in the insert pocket with the peripheral edge surface being abutted at two abutment sections only. According to the teaching of D5, the insert was located at a precise location by means of two abutment sections contacting two flat positioning surfaces of the pocket of the tool holder. A clamp was then pressed against a further abutment section to press the insert against the positioning surfaces. A fastening screw passing through a central hole of the insert was threadably joined to a hole in the tool holder to hold a side surface of the insert against the base surface of the insert pocket. The skilled person would realize that in the embodiment of Fig. 11, in which a triangular insert was used, chips flowed over the abutment surface on which acted the clamp, and that this would affect chip formation. The skilled person would therefore consider using a clamp that did not act onto the abutment surface. A generally known clamp of this type was an eccentric screw, such as disclosed e.g. by D1. Accordingly, the skilled person would omit the clamp in the embodiment of Fig. 11 of D5, and replace the fastening screw by an eccentric screw, thereby arriving at the subject-matter of claim 1 according to the main request without exercising any inventive skill. 2ff7e9595c
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