Title of Invention	A METALLIC CUTTING RING FOR A SCREW CONNECTION FOR SEALINGLY CONNECTING A TUBE TO AN ATTACHMENT PART
Abstract	The invention relates to a metallic cutting ring (1) for a screw connection for sealingly connecting a tube to an attachment part, which metallic cutting ring (1) has a tube abutment section (1a) and a cutting section (1b) which adjoins the tube abutment section (1a) in the axial direction, with the cutting section (1b) having a stop (4) which points radially outward from the outer periphery of the cutting ring (1) and has a stop face (5), which runs transversely with respect to the cutting ring Longitudinal axis (X-X), for the attachment part (3) . In order to obtain improved ease of assembly and therefore reduce the complexity of the method for producing the threaded joint while providing a high degree of sealing action, it is proposed that the stop (4) for the attachment part (3) has an annular peripheral stop edge (9) which projects beyond the stop face (5) .

Title of Invention

A METALLIC CUTTING RING FOR A SCREW CONNECTION FOR SEALINGLY CONNECTING A TUBE TO AN ATTACHMENT PART

Abstract

The invention relates to a metallic cutting ring (1) for a screw connection for sealingly connecting a tube to an attachment part, which metallic cutting ring (1) has a tube abutment section (1a) and a cutting section (1b) which adjoins the tube abutment section (1a) in the axial direction, with the cutting section (1b) having a stop (4) which points radially outward from the outer periphery of the cutting ring (1) and has a stop face (5), which runs transversely with respect to the cutting ring Longitudinal axis (X-X), for the attachment part (3) . In order to obtain improved ease of assembly and therefore reduce the complexity of the method for producing the threaded joint while providing a high degree of sealing action, it is proposed that the stop (4) for the attachment part (3) has an annular peripheral stop edge (9) which projects beyond the stop face (5) .

Full Text	11184 PCT/VIII VOSS Fluid GmbH & Co. KG Ludenscheider Str. 52-54, D-51688 Wipperfiirth "Metallic cutting ring" The present invention relates to a metallic cutting ring for a screw connection for sealingly connecting a tube to an attachment part, having a tube abutment section, and having a cutting section which adjoins the tube abutment section in the axial direction, with the cutting section having a radially outwardly facing stop with a stop face, which runs transversely with respect to the cutting ring longitudinal axis, for the attachment part. Screw connections having similar rings are known from DE-B 1 167 608, DE-B 1 175 639, GB 1 117 987 A and US 2 406 488, in all of which screw connections, however, the stop for the stop part is situated on the end side of the cutting ring. For example, DE-B 1 167 608 describes an threaded attachment joint for tubes, which threaded attachment joint is composed, in terms of one of its parts, of an attachment piece which has an end face which runs perpendicular to the tube axis and a simi lar Ly- running annular face for supporting the tube end. In addition, the known threaded joint is composed, in terms of the other of its parts, of a sleeve nut which encloses the tube end and can be screwed onto the attachment piece, and of a hardened sealing ring which is arranged on the tube end and, as the sleeve nut is tightened, bites with a radially inward aligned cutting edge, which is arranged in the region of its rear end, into the tube outer face and bites with an end-side annular cutting edge, which can also be regarded as a stop, into the end face of the attachment piece, with that part of the sealing ring which adjoins the end-side annular cutting 11184 PCT/VIII - 2 - edge being guided, with little play, at the outside by the wall of the cylindrical bore adjoining the end face, and at the inside by the outer face of the tube end. DE-B 1 175 639 describes a method for producing a sealing ring for tube connections, which sealing ring, between the receiving cone of an attachment piece and a press-in piece which interacts with said attachment piece, bites with a hard cutting edge into the outer casing of the tube which is to be attached as said press-in piece is axially displaced, with the front part of the sealing ring being altered from a cylindrical shape into a conical shape by means of rotating rollers until a Jug is formed which projects beyond the outer edge of the front part. GB 1 117 987 A describes a tube coupling with which, as a tube is attached, the tube end can be expanded. Serving this purpose is, inter alia, a ring, referred to as a "tube-flaring sleeve", which fixedly holds the tube which is to be expanded by means of a radially inwardly aligned cutting edge when, during attachment, the end of said tube is pressed against a conical, centrally arranged expanding body, referred to as a "flaring member". At the end side, the expanded tube portion comes into contact with a radially outer conical face of a mating bore. The ring, at the end side at an end which faces towards the expanding body and the mating bore, has a radial cutting edge and axiaily outwardly and inwardly aligned inclined faces which have different bevel angles and are matched to the conical faces of the expanding body and the mating bore . A tube connection having a cutting ring is known from US 2 406 488, which cutting ring has a flange which points obliquely radially inward and, during 11184 PCT/VIII - 3 - attachment, is bent back, by an attachment piece which bears against it, from an original inclined position into a position aligned approximately perpendicular to the longitudinal axis of the connection, and thereby cuts into the casing of the tube which JS to be connected. The cutting ring also has, on an end face -at the outside adjacent to the flange - an axial Jy aligned annular rib which, during attachment, comes into contact as a stop against the attachment, piece and thereby stops the bending movement of the flange. A metallic cutting ring which corresponds to the type specified in the introduction is known from DE 33 41 726 Al. Said document describes a screw connection for sealingly connecting a tube to a tube connecting part or screw-in part, composed of a body which has a bore which narrows conically in a continuous fashion from an end face to the interior of the body, of a nut which can be screwed onto the body and has a bore which narrows conicaily away from the body, and of an intermediate ring which is provided at its end facing the body with a plurality of radially inwardly aligned cutting edges and is held in a clamped fashion between the conical bore in the body and the conical bore m the nut. This is intended to achieve the object of providing, with the intermediate ring, a cutting ring which, while having a high degree of axial strength, has a low degree of deformation work in the radial direction. This is achieved in that axial!y aligned ribs are arranged so as to be uniformly distributed on the periphery of a solid region of the cutting ring. It is possible by means of a targeted formation of the ribs to provide the cutting ring with an elastic behavior which is matched to the respective requirements. In order to additionally provide that the end of the assembly process is clearly signaled to the assembly personnel, it is provided that nut-side conical stop faces of the solid region and of the rib 11184 PCT/VIII - 4 - region are held offset against one another in a defined way. In the known cutting ring, an annular bead is provided on the nut-side end, with the ribs being situated on the outside of said annular bead and a tube abutment section being formed in the region of said annular bead, in that an inner lateral surface of said region encloses, in a positively engaging manner, the outer lateral surface of the tube which Ls to be connected. The tube abutment section is adjoined in the axial direction towards the body by a cutting section which has a stop, which points radially outward from the periphery of the cutting ring and runs transversely with respect to the cutting ring longitudinal axis, for the attachment part. A stop face of the stop runs, in one embodiment, perpendicularly with respect to the longitudinal axis of the ring, and in a further embodiment, obliquely with respect to the longitudinal axis of the ring, and in each case merges into said ribs which are situated further radially outward. The stop face acts as a tightening limiter as the nut is tightened, that is to say, when the stop face comes into firm contact with the attachment part, the tightening torque increases abruptly, thereby signaling the end of the assembly process. In contrast to DE-B 1 167 608, in which the cutting ring is held in a resilient fashion between the sleeve nut and the connecting piece, and in which the cutting edge for the tube cannot be arranged in a front region facing the attachment piece, the cutting ring of DE 33 41 726 Al, which corresponds to the type specified in the introduction, permits a limitation of tightening during assembly, which can be carried out as so-called block assembly, and the arrangement of an additional sealing edge in the front ring region. 11184 PCT/V1II - 5 - The present invention is based on the object of providing a metallic cutting ring of the type specified in the introduction which is distinguished by .improved ease of assembly, and therefore a more cost-effective method for producing the threaded joint, while providing a high degree of sealing action. This is achieved according to the invention by a cutting ring of the type specified in the introduction in which the stop for the attachment part has an annular peripheral stop edge which projects beyond the stop face. Said embodiment according to the invention firstly makes it possible, while maintaining all the advantages of the known generic cutting ring, to provide a screw connection for sealingly connecting a tube to an attachment part, which screw connection has an increased level of functionality, since the annular peripheral stop edge which projects beyond the stop face forms an additional sealing edge. In addition, it is possible according to the invention to reduce the assembly expenditure in producing the screw connection in that the stop edge, which is more easily deformable than the stop face, provides tolerance compensation with regard to the axial length dimension of the ring or of the attachment part. Further advantageous embodiment features of the invention are specified in the subclaims and in the following description. The invention is to be explained in more detail on the basis of a preferred exemplary embodiment which is illustrated in the drawing, in which: E'igure 1 shows an axial half-section through a screw connection having a metallic cutting ring 11184 PCT/VIII - 6 - according to the invention, Figure 2 shows, in an enlarged illustration in relation to figure 1, an axial longitudinal section through the metallic cutting ring according to the invention, Figure 3 shows, in an enlarged illustration in relation to figure 2, a detail denoted m figure 2 by X. In the different figures of the drawing, identical and mutually corresponding parts are always provided with the same reference symbols and are therefore also generally described only once m each case. As can initially be seen from figure 1, a metallic cutting ring 1 according to the invention is designed for use for a screw connection SV for sealing]y connecting a tube 2 to an attachment part 3 such as a tube piece or a screw-in part. The cutting ring 1 has a tube abutment section la and a cutting section 1b which adjoins the tube abutment section la in the axial direction, with the cutting section 1b having a stop 4 which points radially outward from the outer periphery of the cutting ring 1 and has a stop face 5, which runs transversely with respect to the cutting ring longitudinal axis X-X, for the attachment part 3, in particular for an end face 3a of the attachment part 3. The attachment part 3 is provided with an axially running conical bore 3b, into which the cutting ring 1 engages partially, that is to say with its cutting section lb. A nut 6 which can be screwed onto an attachment part 3 which is provided with an outer thread 3c is likewise provided - adjacent to its 11184 PCT/VIII - 7 - threaded bore 6a - with a conical bore 6b. Here, the cutting ring 1 is clamped between - in the region of its cutting section lb - the conical bore 3b of the attachment part 3 and - in the region it its tube abutment section la - the conical bore 6b of the nut. 6. At its side facing towards the attachment part 3, that is to say in its cutting section lb, the cutting ring 1 is provided with cutting edges 7, 8, m particular two cutting edges 7, 8 which, as the nut 6 is tightened, slide axially on the attachment part 3, and simultaneously cut radially into the wall 2a of the tube 2 which is to be connected, under the action of the conical bore 3b of the attachment part 3 until the stop 4 is reached. The stop 4 with its radially extending stop face 5 which runs transversely with respect to the cutting ring longitudinal axis on the side facing towards the attachment part 3 acts, as the nut 6 is tightened, as a tightening limiter, that is to say, when the stop face 5 is in firm contact, a torque to be applied for tightening increases abruptly. According to the invention, it is provided here that the stop 4 has, for the attachment part 3, an annular peripheral stop edge 9 which projects beyond the stop face 5, which stop edge 9 cannot be seen in figure 1 but can be gathered from the enlarged illustrations of the cutting ring 1 in figures 2 and 3. The stop edge 9 lorms - as previously mentioned - an additional sealing edge, and promotes tolerance compensation, in particular in the direction of the longitudinai axis X-X, during assembly. At the side of the nut 6, the cutting ring 1 is supported with its annular-bead-like tube abutment section la, which is preferably likewise conical at the outside, on the nut 6 at the outside and on the tube 2 11184 PCT/VIII - 8 - at the inside. As a result of the positively locking contact against the wall 2a of the tube 2, it is ensured here that no notching effects occur on the tube 2 which could reduce the strength of the tube 2. As shown in figure 2 and more clearly in figure 3, it can be provided in a preferred embodiment of the invention that the stop edge 9 divides the stop face 5 into two - one inner and one outer - annular partial faces 5a, 5b which are arranged concentricalLy with respect to one another, with the partial faces 5a, 5b in particular having a different angle of inciination relative to the cutting ring longitudinal axis X-X. In this way, the stop edge 9 can, while having a high degree of stability and strength, be provided with a contour design which is optimized with regard to the abutment and the sealing action thereby produced. Figure 3 shows in particular that the inner partial face 5a widens conicaliy in the direction of the attachment part 3, while the outer partial face 5b narrows conicaliy in the direction of the attachment part 3, so that an obtuse angle a is enclosed between the partial faces 5a, 5b. It is possible by means of the selection of said angle a to define, in a predetermined way, the pressing behavior of the stop edge 9 against the end face 3a of the attachment part 3, for example the increase in the tightening torque once the stop 4 has been reached. The invention is not restricted to the illustrated exemplary embodiment but rather comprises all equivalent embodiments within the scope of the invention. Particularly possible are other embodiments of the stop face 5 and the stop edge 9, insofar as, for example, the stop edge can be designed to be more or less obtuse by varying the angle a or by means of a possible slight rounding of the tip of the edge. 11184 PCT/VIII - 9 - With regard in particular to the angle of inclination of the inner partial face 5a relative to the cutting ring longitudinal axis X-X, said angle of inclination can, for example, deviate from a perpendicular profile to only a small degree, in particular by less than the angle of inclination of the outer partial face 5b, for example by up to a maximum of 25°, preferably by less than 15°. Here, it is possible to provide a rounding R at a fillet generated by a recess of the outer diameter Dla of a preferably cylindrical region laz of the outer contour of the tube abutment section la to the outer diameter Dlb of a preferably likewise cylindrical region lbz of the outer contour of the cutting edge lb, which rounding R leads to an optimization of the profile of the mechanical stresses in the assembled cutting ring 1. The invention is also not restricted to the combination of features defined in claim 1, but can also be defined by any other desired combination of features of al] the individual features disclosed. This means that fundamentally any individual feature of claim 1 can be omitted or replaced by at least one feature disclosed elsewhere in the application. Claim 1 is therefore to be understood merely as a first attempt at formulating an invention. 11184 PCT/VIII - 10 - Reference symbols 1 Cutting ring la Tube abutment section of 1 lb Cutting section of 1 laz Cylindrical region of la lbz Cylindrical region of lb 2 Tube 2a Wall of 2 3 Attachment part 3a End face of 3 3b Conical bore in 3 3c Outer thread of 3 4 Stop on 1 5 Stop face on 4 5a Inner partial face of 5 5b Outer partial face of 5 6 Nut 6a Threaded bore in 6 6b Conical bore in 6 7, 8 Cutting edges of 1 9 Stop edge of 4 Dla Outer diameter of laz Dlb Outer diameter of lbz R Rounding SV Screw connection composed of 1, 2, 3 X-X Longitudinal axis of 1, SV a Angle between 5a and 5b 11184 PCT/VIII - 11 - Claims 1. A metallic cutting ring (1) for a screw connection (SV) for sealingly connecting a tube (2) to an attachment part (3), having a tube abutment section (la), and having a cutting section (lb) which adjoins the tube abutment section (la) in the axial direction, with the cutting section (lb) having a stop (4) which points radially outward from the outer periphery of the cutting ring (1) and has a stop face (5) , which runs transversely with respect to the cutting ring longitudinal axis (X-X), for the attachment part (3), characterized in that the stop (4) for the attachment part (3) has an annular peripheral stop edge (9) which projects beyond the stop face (5). 2. The cutting ring as claimed in claim 1, characterized in that the stop edge (9) divides the stop face (5) into two - one inner and one outer - annular partial faces (ba, 5b) which are arranged concentrically with respect to one another. 3. The cutting ring as claimed in claim 2, characterized in that the partial faces (5a, 5b) have a different angle of inclination relative to the cutting ring longitudinal axis (X-X). 4. The cutting ring as claimed in claim 2 or 3, characterized m that the inner partial face (5a) widens conically in the direction of the attachment part (3) . 5. The cutting ring as claimed in one of claims 2 to 4, characterized in that the outer partial face (5b) narrows conically in the direction of the 11184 PCT/VIII - 12 - attachment part (3). 6. The cutting ring as claimed in one of claims 2 to 5, characterized in that a/the angle of inclination of the inner partial face (5a) relative to the cutting ring longitudinal axis (X-X) deviates from a perpendicular profile relative to the cutting ring longitudinal axis (X-X) Joy up to 25°, in particular by less than 15°.

Full Text

11184 PCT/VIII
VOSS Fluid GmbH & Co. KG
Ludenscheider Str. 52-54, D-51688 Wipperfiirth
"Metallic cutting ring"
The present invention relates to a metallic cutting ring for a screw connection for sealingly connecting a tube to an attachment part, having a tube abutment section, and having a cutting section which adjoins the tube abutment section in the axial direction, with the cutting section having a radially outwardly facing stop with a stop face, which runs transversely with respect to the cutting ring longitudinal axis, for the attachment part.
Screw connections having similar rings are known from DE-B 1 167 608, DE-B 1 175 639, GB 1 117 987 A and US 2 406 488, in all of which screw connections, however, the stop for the stop part is situated on the end side of the cutting ring.
For example, DE-B 1 167 608 describes an threaded attachment joint for tubes, which threaded attachment joint is composed, in terms of one of its parts, of an attachment piece which has an end face which runs perpendicular to the tube axis and a simi lar Ly- running annular face for supporting the tube end. In addition, the known threaded joint is composed, in terms of the other of its parts, of a sleeve nut which encloses the tube end and can be screwed onto the attachment piece, and of a hardened sealing ring which is arranged on the tube end and, as the sleeve nut is tightened, bites with a radially inward aligned cutting edge, which is arranged in the region of its rear end, into the tube outer face and bites with an end-side annular cutting edge, which can also be regarded as a stop, into the end face of the attachment piece, with that part of the sealing ring which adjoins the end-side annular cutting

11184 PCT/VIII - 2 -
edge being guided, with little play, at the outside by the wall of the cylindrical bore adjoining the end face, and at the inside by the outer face of the tube end.
DE-B 1 175 639 describes a method for producing a sealing ring for tube connections, which sealing ring, between the receiving cone of an attachment piece and a press-in piece which interacts with said attachment piece, bites with a hard cutting edge into the outer casing of the tube which is to be attached as said press-in piece is axially displaced, with the front part of the sealing ring being altered from a cylindrical shape into a conical shape by means of rotating rollers until a Jug is formed which projects beyond the outer edge of the front part.
GB 1 117 987 A describes a tube coupling with which, as a tube is attached, the tube end can be expanded. Serving this purpose is, inter alia, a ring, referred to as a "tube-flaring sleeve", which fixedly holds the tube which is to be expanded by means of a radially inwardly aligned cutting edge when, during attachment, the end of said tube is pressed against a conical, centrally arranged expanding body, referred to as a "flaring member". At the end side, the expanded tube portion comes into contact with a radially outer conical face of a mating bore. The ring, at the end side at an end which faces towards the expanding body and the mating bore, has a radial cutting edge and axiaily outwardly and inwardly aligned inclined faces which have different bevel angles and are matched to the conical faces of the expanding body and the mating bore .
A tube connection having a cutting ring is known from US 2 406 488, which cutting ring has a flange which points obliquely radially inward and, during

11184 PCT/VIII - 3 -
attachment, is bent back, by an attachment piece which bears against it, from an original inclined position into a position aligned approximately perpendicular to the longitudinal axis of the connection, and thereby cuts into the casing of the tube which JS to be connected. The cutting ring also has, on an end face -at the outside adjacent to the flange - an axial Jy aligned annular rib which, during attachment, comes into contact as a stop against the attachment, piece and thereby stops the bending movement of the flange.
A metallic cutting ring which corresponds to the type specified in the introduction is known from DE 33 41 726 Al. Said document describes a screw connection for sealingly connecting a tube to a tube connecting part or screw-in part, composed of a body which has a bore which narrows conically in a continuous fashion from an end face to the interior of the body, of a nut which can be screwed onto the body and has a bore which narrows conicaily away from the body, and of an intermediate ring which is provided at its end facing the body with a plurality of radially inwardly aligned cutting edges and is held in a clamped fashion between the conical bore in the body and the conical bore m the nut. This is intended to achieve the object of providing, with the intermediate ring, a cutting ring which, while having a high degree of axial strength, has a low degree of deformation work in the radial direction. This is achieved in that axial!y aligned ribs are arranged so as to be uniformly distributed on the periphery of a solid region of the cutting ring. It is possible by means of a targeted formation of the ribs to provide the cutting ring with an elastic behavior which is matched to the respective requirements. In order to additionally provide that the end of the assembly process is clearly signaled to the assembly personnel, it is provided that nut-side conical stop faces of the solid region and of the rib

11184 PCT/VIII - 4 -
region are held offset against one another in a defined way. In the known cutting ring, an annular bead is provided on the nut-side end, with the ribs being situated on the outside of said annular bead and a tube abutment section being formed in the region of said annular bead, in that an inner lateral surface of said region encloses, in a positively engaging manner, the outer lateral surface of the tube which Ls to be connected.
The tube abutment section is adjoined in the axial direction towards the body by a cutting section which has a stop, which points radially outward from the periphery of the cutting ring and runs transversely with respect to the cutting ring longitudinal axis, for the attachment part. A stop face of the stop runs, in one embodiment, perpendicularly with respect to the longitudinal axis of the ring, and in a further embodiment, obliquely with respect to the longitudinal axis of the ring, and in each case merges into said ribs which are situated further radially outward. The stop face acts as a tightening limiter as the nut is tightened, that is to say, when the stop face comes into firm contact with the attachment part, the tightening torque increases abruptly, thereby signaling the end of the assembly process.
In contrast to DE-B 1 167 608, in which the cutting ring is held in a resilient fashion between the sleeve nut and the connecting piece, and in which the cutting edge for the tube cannot be arranged in a front region facing the attachment piece, the cutting ring of DE 33 41 726 Al, which corresponds to the type specified in the introduction, permits a limitation of tightening during assembly, which can be carried out as so-called block assembly, and the arrangement of an additional sealing edge in the front ring region.

11184 PCT/V1II - 5 -
The present invention is based on the object of providing a metallic cutting ring of the type specified in the introduction which is distinguished by .improved ease of assembly, and therefore a more cost-effective method for producing the threaded joint, while providing a high degree of sealing action.
This is achieved according to the invention by a cutting ring of the type specified in the introduction in which the stop for the attachment part has an annular peripheral stop edge which projects beyond the stop face.
Said embodiment according to the invention firstly makes it possible, while maintaining all the advantages of the known generic cutting ring, to provide a screw connection for sealingly connecting a tube to an attachment part, which screw connection has an increased level of functionality, since the annular peripheral stop edge which projects beyond the stop face forms an additional sealing edge. In addition, it is possible according to the invention to reduce the assembly expenditure in producing the screw connection in that the stop edge, which is more easily deformable than the stop face, provides tolerance compensation with regard to the axial length dimension of the ring or of the attachment part.
Further advantageous embodiment features of the invention are specified in the subclaims and in the following description.
The invention is to be explained in more detail on the basis of a preferred exemplary embodiment which is illustrated in the drawing, in which:
E'igure 1 shows an axial half-section through a screw connection having a metallic cutting ring

11184 PCT/VIII - 6 -
according to the invention,
Figure 2 shows, in an enlarged illustration in relation to figure 1, an axial longitudinal section through the metallic cutting ring according to the invention,
Figure 3 shows, in an enlarged illustration in relation to figure 2, a detail denoted m figure 2 by X.
In the different figures of the drawing, identical and mutually corresponding parts are always provided with the same reference symbols and are therefore also generally described only once m each case.
As can initially be seen from figure 1, a metallic cutting ring 1 according to the invention is designed for use for a screw connection SV for sealing]y connecting a tube 2 to an attachment part 3 such as a tube piece or a screw-in part.
The cutting ring 1 has a tube abutment section la and a cutting section 1b which adjoins the tube abutment section la in the axial direction, with the cutting section 1b having a stop 4 which points radially outward from the outer periphery of the cutting ring 1 and has a stop face 5, which runs transversely with respect to the cutting ring longitudinal axis X-X, for the attachment part 3, in particular for an end face 3a of the attachment part 3.
The attachment part 3 is provided with an axially running conical bore 3b, into which the cutting ring 1 engages partially, that is to say with its cutting section lb. A nut 6 which can be screwed onto an attachment part 3 which is provided with an outer thread 3c is likewise provided - adjacent to its

11184 PCT/VIII - 7 -
threaded bore 6a - with a conical bore 6b. Here, the cutting ring 1 is clamped between - in the region of its cutting section lb - the conical bore 3b of the attachment part 3 and - in the region it its tube abutment section la - the conical bore 6b of the nut. 6.
At its side facing towards the attachment part 3, that is to say in its cutting section lb, the cutting ring 1 is provided with cutting edges 7, 8, m particular two cutting edges 7, 8 which, as the nut 6 is tightened, slide axially on the attachment part 3, and simultaneously cut radially into the wall 2a of the tube 2 which is to be connected, under the action of the conical bore 3b of the attachment part 3 until the stop 4 is reached.
The stop 4 with its radially extending stop face 5 which runs transversely with respect to the cutting ring longitudinal axis on the side facing towards the attachment part 3 acts, as the nut 6 is tightened, as a tightening limiter, that is to say, when the stop face 5 is in firm contact, a torque to be applied for tightening increases abruptly. According to the invention, it is provided here that the stop 4 has, for the attachment part 3, an annular peripheral stop edge 9 which projects beyond the stop face 5, which stop edge 9 cannot be seen in figure 1 but can be gathered from the enlarged illustrations of the cutting ring 1 in figures 2 and 3. The stop edge 9 lorms - as previously mentioned - an additional sealing edge, and promotes tolerance compensation, in particular in the direction of the longitudinai axis X-X, during assembly.
At the side of the nut 6, the cutting ring 1 is supported with its annular-bead-like tube abutment section la, which is preferably likewise conical at the outside, on the nut 6 at the outside and on the tube 2

11184 PCT/VIII - 8 -
at the inside. As a result of the positively locking contact against the wall 2a of the tube 2, it is ensured here that no notching effects occur on the tube 2 which could reduce the strength of the tube 2.
As shown in figure 2 and more clearly in figure 3, it can be provided in a preferred embodiment of the invention that the stop edge 9 divides the stop face 5 into two - one inner and one outer - annular partial faces 5a, 5b which are arranged concentricalLy with respect to one another, with the partial faces 5a, 5b in particular having a different angle of inciination relative to the cutting ring longitudinal axis X-X. In this way, the stop edge 9 can, while having a high degree of stability and strength, be provided with a contour design which is optimized with regard to the abutment and the sealing action thereby produced.
Figure 3 shows in particular that the inner partial face 5a widens conicaliy in the direction of the attachment part 3, while the outer partial face 5b narrows conicaliy in the direction of the attachment part 3, so that an obtuse angle a is enclosed between the partial faces 5a, 5b. It is possible by means of the selection of said angle a to define, in a predetermined way, the pressing behavior of the stop edge 9 against the end face 3a of the attachment part 3, for example the increase in the tightening torque once the stop 4 has been reached.
The invention is not restricted to the illustrated exemplary embodiment but rather comprises all equivalent embodiments within the scope of the invention. Particularly possible are other embodiments of the stop face 5 and the stop edge 9, insofar as, for example, the stop edge can be designed to be more or less obtuse by varying the angle a or by means of a possible slight rounding of the tip of the edge.

11184 PCT/VIII - 9 -
With regard in particular to the angle of inclination of the inner partial face 5a relative to the cutting ring longitudinal axis X-X, said angle of inclination can, for example, deviate from a perpendicular profile to only a small degree, in particular by less than the angle of inclination of the outer partial face 5b, for example by up to a maximum of 25°, preferably by less than 15°. Here, it is possible to provide a rounding R at a fillet generated by a recess of the outer diameter Dla of a preferably cylindrical region laz of the outer contour of the tube abutment section la to the outer diameter Dlb of a preferably likewise cylindrical region lbz of the outer contour of the cutting edge lb, which rounding R leads to an optimization of the profile of the mechanical stresses in the assembled cutting ring 1.
The invention is also not restricted to the combination of features defined in claim 1, but can also be defined by any other desired combination of features of al] the individual features disclosed. This means that fundamentally any individual feature of claim 1 can be omitted or replaced by at least one feature disclosed elsewhere in the application. Claim 1 is therefore to be understood merely as a first attempt at formulating an invention.

11184 PCT/VIII - 10 -
Reference symbols
1 Cutting ring
la Tube abutment section of 1
lb Cutting section of 1
laz Cylindrical region of la
lbz Cylindrical region of lb
2 Tube
2a Wall of 2
3 Attachment part
3a End face of 3
3b Conical bore in 3
3c Outer thread of 3
4 Stop on 1
5 Stop face on 4
5a Inner partial face of 5
5b Outer partial face of 5
6 Nut
6a Threaded bore in 6
6b Conical bore in 6
7, 8 Cutting edges of 1
9 Stop edge of 4
Dla Outer diameter of laz
Dlb Outer diameter of lbz
R Rounding
SV Screw connection composed of 1, 2, 3
X-X Longitudinal axis of 1, SV
a Angle between 5a and 5b

11184 PCT/VIII - 11 -
Claims
1. A metallic cutting ring (1) for a screw connection
(SV) for sealingly connecting a tube (2) to an attachment part (3), having a tube abutment section (la), and having a cutting section (lb) which adjoins the tube abutment section (la) in the axial direction, with the cutting section (lb) having a stop (4) which points radially outward from the outer periphery of the cutting ring (1) and has a stop face (5) , which runs transversely with respect to the cutting ring longitudinal axis
(X-X), for the attachment part (3),
characterized in that the stop (4) for the attachment part (3) has an annular peripheral stop edge (9) which projects beyond the stop face (5).
2. The cutting ring as claimed in claim 1,
characterized in that the stop edge (9) divides
the stop face (5) into two - one inner and one
outer - annular partial faces (ba, 5b) which are
arranged concentrically with respect to one
another.
3. The cutting ring as claimed in claim 2,
characterized in that the partial faces (5a, 5b)
have a different angle of inclination relative to
the cutting ring longitudinal axis (X-X).
4. The cutting ring as claimed in claim 2 or 3,
characterized m that the inner partial face (5a)
widens conically in the direction of the
attachment part (3) .
5. The cutting ring as claimed in one of claims 2 to
4,
characterized in that the outer partial face (5b) narrows conically in the direction of the

11184 PCT/VIII - 12 -
attachment part (3).
6. The cutting ring as claimed in one of claims 2 to 5,
characterized in that a/the angle of inclination of the inner partial face (5a) relative to the cutting ring longitudinal axis (X-X) deviates from a perpendicular profile relative to the cutting ring longitudinal axis (X-X) Joy up to 25°, in particular by less than 15°.

A METALLIC CUTTING RING FOR A SCREW CONNECTION FOR SEALINGLY CONNECTING A TUBE TO AN ATTACHMENT PART

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