CUTTING ELEMENT

A cutting element has a cutting head and a shaft. The cutting head is carried by the shaft and protrudes over the shaft transversely relative to a longitudinal extent of the shaft. The cutting head has a cutting edge, the cutting edge follows a circle segment with a circle center at a side of the shaft located in a virtual cutting head plane and is constructed symmetrically, when viewed in a direction perpendicular to the cutting head plane, with respect to a virtual cutting edge axis of symmetry which is contained in the cutting head plane. The cutting head has a chip guiding structure. The chip guiding structure is associated with the cutting edge, has a chip guiding groove and a plurality of chip guiding elements. Each chip guiding element has a longitudinal rib and a transverse rib.

The present invention relates to a cutting element, wherein the cutting element has a cutting head and a shaft, wherein the cutting head is carried by the shaft and protrudes over the shaft transversely relative to the longitudinal extent of the shaft, wherein the cutting head has a cutting edge, wherein the cutting edge follows a circle segment with a circle centre at the side of the shaft, is located in a virtual cutting head plane and is constructed symmetrically, when viewed in a direction perpendicular to the cutting head plane with respect to a virtual cutting edge axis of symmetry which is contained in the cutting head plane, wherein the cutting head has a chip guiding structure, wherein the chip guiding structure is associated with the cutting edge.

Such a cutting element can be used to produce grooves in a workpiece while rotating at different feed angles. The chip guiding structure guides the chips produced during feeding away from the cutting edge with a chip breakage so that the chips do not impair the feed process.

DE 10 2014 116 660 A1 sets out a cutting insert. In the cutting insert known from DE 10 2014 116 660 A1 there is a requirement to break the chips so as to be shorter.

An object of the present invention is to provide a cutting element with improved chip breakage.

The technical objective of the present invention is achieved with the subject-matter of claim1. Advantageous further developments of the invention can be derived from the dependent claims, which can be freely combined with each other, and the Figures.

According to the present invention, the cutting element has a cutting head and a shaft, wherein the cutting head is carried by the shaft and protrudes over the shaft transversely relative to the longitudinal extent of the shaft, wherein the cutting head has a cutting edge, wherein the cutting edge follows a circle segment with a circle centre at the side of the shaft, is located in a virtual cutting head plane and is constructed symmetrically, when viewed in a direction perpendicular to the cutting head plane, with respect to a virtual cutting edge axis of symmetry which is contained in the cutting head plane, wherein the cutting head has a chip guiding structure, wherein the chip guiding structure is associated with the cutting edge, wherein the chip guiding structure has a chip guiding groove which is constructed to follow the cutting edge when viewed in a direction perpendicular to the cutting head plane and a plurality of chip guiding elements which are constructed in the region of the chip guiding groove, wherein each chip guiding element has a longitudinal rib and a transverse rib, wherein the longitudinal rib of each chip guiding element has a rib ridge and rib flanks which decline from the rib ridge at both sides, wherein the rib ridge of each longitudinal rib, when viewed in a direction perpendicular to the cutting head plane, extends in each case substantially radially away from the cutting edge and is arranged between the transverse rib and the cutting edge, wherein in each chip guiding element the transverse rib protrudes, when viewed in a direction perpendicular to the cutting head plane, transversely relative to the longitudinal extent of the rib ridge over the rib ridge so that chips when rising from the chip guiding groove strike the transverse rib when the chips are guided by the longitudinal rib.

The transverse rib ensures in each chip guiding element that the chips are compressed when rising from the chip guiding groove and thus break more easily.

The longitudinal rib in each chip guiding element ensures that the chips are guided from the cutting edge to the transverse rib and at the same time are prevented from laterally escaping transversely relative to the rib ridge.

Between the transverse ribs of two chip guiding elements which are adjacent to each other when viewed in a direction perpendicular to the cutting head plane, a transverse rib valley is formed. As a result of the transverse rib valley, coolant fluid can reach the cutting edge.

The transverse rib and the longitudinal rib may in at least one of the chip guiding elements form an integral projection in the chip guiding groove or the transverse rib and the longitudinal rib can in at least one chip guiding element be spaced apart from each other in a radial direction with respect to the cutting edge in the chip guiding groove.

Preferably, at least two of the rib ridges terminate with the same spatial spacing in each case with respect to the cutting edge. This makes the chip guiding away from the cutting edge homogeneous under various feed angles.

The rib ridges have in each chip guiding element a rib ridge face, wherein the rib flanks decline from the rib ridge face at both sides with an edge being formed.

Preferably, at least one of the chip guiding elements has a longitudinal rib base, wherein the longitudinal rib base carries the longitudinal rib of the chip guiding element with the longitudinal rib base. The longitudinal rib base preferably has longitudinal rib base flanks, wherein the longitudinal rib base flanks decline at both sides from the rib flanks with an edge being formed and, when viewed in a direction perpendicular to the cutting head plane, protrude over the rib flanks. The longitudinal rib base flanks make the transition from the longitudinal rib to the chip guiding groove gentler so that the longitudinal rib starting from a powdered material can be pressed and sintered in a more homogeneous manner.

The cutting edge may have a cutting edge chamfer, wherein the cutting edge chamfer is a portion of the chip guiding structure and wherein the cutting edge chamfer is connected to at least one longitudinal rib with an edge being formed. The chips can slide from the cutting edge chamfer along the rib flanks of this longitudinal rib into the chip guiding groove so that the chips are pre-deformed with respect to their deformation on the transverse rib.

The chip guiding groove declines at the side of the cutting edge and rises at the side of the transverse ribs.

The chip guiding groove follows the cutting edge when viewed in a direction perpendicular to the cutting head plane.

The term “extends substantially radially away” is intended to mean with respect to the longitudinal ribs that the rib ridges, when viewed in a direction perpendicular to the cutting head plane, can each be rotated with respect to a radial starting position about the radial starting position in the range from −15° to +15°. 0° is the radial starting position.

The cutting head is preferably formed from a hard metal (cemented carbide).

Hard metal is a composite material, wherein the composite material has a frame structure, wherein the frame structure is formed by means of hard material particles and has intermediate spaces.

The hard material particles may in particular be formed at least primarily from tungsten carbide, titanium carbide and/or titanium carbonitride, wherein in smaller quantities in addition, for example, other hard material particles, in particular carbides of the elements of the groups IV to VI of the periodic table, may also be present.

The intermediate spaces are filled with a metal intermediate space material, wherein the intermediate space material is formed at least primarily from cobalt, nickel, iron or a base alloy of at least one of these elements. However, other elements may also be dissolved in smaller quantities in the metal intermediate space material.

The term “base alloy” is intended to be understood to mean that this element forms the main component of the alloy. Most often, hard metal is used in which the hard material particles are formed at least primarily by tungsten carbide and the intermediate space material is a cobalt or cobalt/nickel base alloy; the proportion by weight of the corresponding tungsten carbide particles is in this case in particular at least 70% by weight, preferably more than 80% by weight, most preferably more than 90 percent by weight.

The cutting head and the shaft are preferably constructed as an integral element so that no boundary is formed between the cutting head and the shaft. The stability of the cutting element is thereby increased.

According to a further development of the cutting element, the transverse rib in at least one chip guiding element, in a rib longitudinal section which is orientated radially with respect to the cutting edge, when viewed in a direction perpendicular to the rib longitudinal section, is curved in a convex manner at the side of the rib ridge. This ensures that the chips under the compression brought about by the transverse rib can slide better along the transverse rib. A chip blockage on the transverse rib is better prevented, which further improves the chip removal. Preferably, the transverse rib is similarly curved in a convex manner in each chip guiding element of the transverse rib of this further development.

The rib longitudinal section preferably extends centrally through the rib ridge when viewed in a direction perpendicular to the cutting head plane.

According to a further development of the cutting element, the longitudinal rib, in the at least one chip guiding element in the rib longitudinal section which is orientated radially with respect to the cutting edge, when viewed in a direction perpendicular to the rib longitudinal section, is curved in a concave manner at the side of the cutting edge. This ensures that the chips can slide better into the chip guiding groove.

According to a further development of the cutting element, at least one chip guiding element is, in a rib longitudinal section orientated radially with respect to the cutting edge, when viewed in a direction perpendicular to the rib longitudinal section, in the form of a capital letter S, wherein one curve of the capital letter S is formed in the region of the transverse rib so that the transverse rib is curved outwards, wherein the other curve of the capital letter S is formed in the region of the rib ridge so that the rib ridge is curved inwards. The chip guiding element of this further development ensures that the chips when rising from the chip guiding groove are compressed by the transverse rib directly after leaving the longitudinal rib. The chips are additionally impeded from coiling backwards in the direction towards the cutting edge.

Furthermore, chips which are guided on the rib ridge are also bent over and can thus strike the transverse rib. The rib longitudinal section of this further development may be arranged in a similar manner to the rib longitudinal section described with respect to the convex transverse rib.

According to a further development of the cutting element, in at least one chip guiding element the transverse rib, when viewed in a direction perpendicular to the cutting head plane, protrudes over the rib ridge at both sides transversely relative to the longitudinal extent of the rib ridge. The chips are according to this further development deformed at both sides with respect to the rib ridge by the transverse rib, which increases the proportion of deformed chips to the advantage of the chip guiding in the event of a chip breaking away from the cutting edge.

According to a further development of the cutting element, in at least one chip guiding element the transverse rib is, when viewed in a direction perpendicular to the cutting head plane, in the form of a capital letter D, wherein the curve of the capital letter D faces the cutting edge when viewed in a direction perpendicular to the cutting head plane. The D shape of the transverse rib ensures that the chips are deformed on the transverse rib transversely to the longitudinal extent of the rib ridge without any risk of a chip blockage increasing.

According to a further development of the cutting element, at least one chip guiding element has a rib base, wherein the rib base carries the transverse rib with an edge being formed with the transverse rib, protrudes, when viewed in a direction perpendicular to the cutting head plane, transversely with respect to the longitudinal extent of the rib ridge over the transverse rib with a base flank being formed at both sides and carries an end portion of the longitudinal rib. The rib base makes the ascent towards the transverse rib by the longitudinal rib with respect to the chip guiding groove steeper so that the chips are even more powerfully deformed before the chips strike the transverse rib.

According to a further development of the chip guiding element, the chip guiding structure has a plurality of additional chip guiding elements, wherein the additional chip guiding elements are formed in the region of the chip guiding groove, wherein each additional chip guiding element has a longitudinal rib having a rib ridge and rib flanks which decline from the rib ridge at both sides, wherein the rib ridge of each additional chip guiding element, when viewed in a direction perpendicular to the cutting head plane, extends in each case substantially radially away from the cutting edge, wherein each additional chip guiding element, when viewed in a direction perpendicular to the cutting head plane, has an end portion which is free from transverse ribs, wherein each end portion is opposite the cutting edge when viewed in a direction perpendicular to the cutting head plane, wherein the additional chip guiding elements and the chip guiding elements, when viewed in a direction perpendicular to the cutting head plane, are arranged alternately in an alternating manner with respect to each other in a circumferential direction of the cutting edge. The additional chip guiding elements are constructed in a similar manner to the chip guiding elements, but with the additional chip guiding elements not having any transverse rib in the region of the transverse ribs of the chip guiding elements. The additional chip guiding elements ensure that chips which are further away from the chip guiding elements are guided to the transverse ribs without the transverse rib valleys being blocked.

According to a further development of the cutting element, the longitudinal rib of one of the additional chip guiding elements is located, when viewed in a direction perpendicular to the cutting head plane, substantially centrally on the cutting edge axis of symmetry. The longitudinal rib of the additional chip guiding element is a central chip divider which supplies the chips, when viewed in a direction perpendicular to the cutting head plane, to the adjacent transverse ribs at each side of the longitudinal rib.

According to a further development of the cutting element, in at least one additional chip guiding element the longitudinal rib has a rib hump, wherein the rib hump, when viewed in a direction perpendicular to the cutting head plane, is formed and arranged at the side of the cutting edge, wherein the rib hump protrudes from the cutting head plane. The rib hump supports the chip guiding into the chip guiding groove by the rib hump ploughing through the chips during feeding.

According to a further development of the cutting element, the chip guiding structure has a plurality of recesses at the side of the cutting edge, wherein the recesses and the chip guiding elements are arranged alternately in an alternating manner when viewed in a direction perpendicular to the cutting head plane. The recesses ensure a pre-deformation of the chips when the chips slide from the cutting edge into the chip guiding groove. Preferably, the recesses, the chip guiding elements and the additional chip guiding elements are arranged alternately in an alternating manner with respect to each other when viewed in a direction perpendicular to the cutting head plane so that one of the recesses follows one of the chip guiding elements and one of the additional chip guiding elements follows this recess. The term “recesses” is also intended to be understood to include double recesses, according to which such double recesses and the chip guiding elements are arranged alternately in an alternating manner when viewed in a direction perpendicular to the cutting head plane. Double recesses increase the deformation of the chips.

According to a further development of the cutting element, the chip guiding structure has a cutting edge chamfer, wherein the cutting edge chamfer, when viewed in a direction perpendicular to the cutting head plane, has at least one V-shaped protuberance, wherein the V-shaped protuberance extends substantially radially away from the cutting edge, is planar and with an edge being formed is connected to the rib ridge of a longitudinal rib of at least one of the chip guiding elements, wherein the rib flanks of this longitudinal rib decline from the cutting edge chamfer laterally at both sides in the region of the V-shaped protuberance. The cutting edge chamfer ensures that the chips can slide better into the chip guiding groove.

According to a further development of the cutting element, the shaft has a V-shaped groove, wherein the V-shaped groove extends along the longitudinal extent of the shaft. The V-shaped groove ensures that the cutting element at the side of the shaft in a positive-locking manner can be better clamped in a reversibly releasable manner in a cutting element holder.

According to a further development of the cutting element, the cutting element has an additional cutting head, wherein the additional cutting head is carried by the shaft opposite the cutting head. When the cutting head is worn, the cutting element can be rotated in such a manner that the feeding with the additional cutting head can be continued. The additional cutting head is preferably constructed in a similar manner to the cutting head.

According to a further development of the cutting element, the transverse rib of at least one of the chip guiding elements protrudes at least partially from the cutting head plane. The transverse rib according to this further development is particularly good at impeding the chips from being able to become coiled in the direction towards the cutting edge.

According to a further development of the cutting element, the chip guiding elements, when viewed in a direction perpendicular to the cutting head plane, are arranged symmetrically with respect to the cutting edge axis of symmetry. According to this further development, the chip removal provided by the individual chip guiding elements is produced with respect to a plurality of feed angles.

EMBODIMENT

One embodiment of a cutting element1is described with reference toFIGS.1to6.

The cutting element1has a cutting head2and a shaft3. The cutting head2is carried by the shaft3and protrudes transversely relative to the longitudinal extent of the shaft3over the shaft3.

The cutting head1has a cutting edge4. The cutting edge4follows a circle segment having a circle centre5at the side of the shaft3. The cutting edge4is located in this instance in a virtual cutting head plane6. The virtual cutting head plane6coincides in each case with the drawing plane ofFIG.1andFIG.2.

The cutting edge4, when viewed in a direction perpendicular to the cutting head plane6, that is, when viewed in a direction perpendicular to the drawing plane ofFIG.1andFIG.2, is constructed symmetrically with respect to a virtual cutting edge axis7of symmetry contained in the cutting head plane6.

The cutting head2has a chip guiding structure8. The chip guiding structure8is associated with the cutting edge4so that chips produced by the cutting edge4are guided away from the cutting edge4during feeding with chip breakage.

The chip guiding structure8has a chip guiding groove9which is constructed to follow the cutting edge4when viewed in a direction perpendicular to the cutting head plane6and a plurality of chip guiding elements10which are constructed in the region of the chip guiding groove9; of the chip guiding elements10, inFIG.1for reasons of clarity only one of the chip guiding elements10is designated10.

The rib ridge13of each longitudinal rib13when viewed in a direction perpendicular to the cutting head plane6extends radially away from the cutting edge4in each case and is arranged between the transvers rib12and the cutting edge4, as shown in particular inFIG.2.

The transverse rib12in each chip guiding element10, when viewed in a direction perpendicular to the cutting head plane6, protrudes transversely relative to the longitudinal extent of the rib ridge13beyond the rib ridge13at both sides so that chips when rising from the chip guiding groove9strike the transverse rib12when the chips are guided from the longitudinal rib11.

The cutting head2has a central portion15. The chip guiding groove9extends, when viewed in a direction perpendicular to the cutting head plane6, between the cutting edge4and the central portion15. The chip guiding groove9declines at the side of the cutting edge4and rises at the side of the central portion15so that the chip guiding groove9bends the chips so as to follow the path of the chip guiding groove9in a radial direction with respect to the cutting edge4, wherein the chips are additionally deformed at locations where the chips contact the chip guiding elements10. The transverse ribs12increase the degree of deformation of the chips which has already been provided per se by the chip guiding groove9since the transverse ribs12are in each case formed and arranged at the side of the incline of the chip guiding groove9. This leads to a shorter chip breakage and counteracts the formation of snarl chips.

In each chip guiding element10, the transverse rib12is, when viewed in a direction perpendicular to the cutting head plane6, in the form of the capital letter D, wherein the curve of the capital letter D faces the cutting edge4when viewed in a direction perpendicular to the cutting head plane6.

Each chip guiding element10has a rib base16, wherein the rib base16carries the transverse rib12with an edge being formed with the transverse rib12, when viewed in a direction perpendicular to the cutting head plane6, protrudes transversely with respect to the longitudinal extent of the rib ridge13beyond the transverse rib12with a base flank17formation at both sides and carries an end portion18of the longitudinal rib11, as shown in particular inFIG.2. The rib base16makes the incline in the region of the chip guiding groove9steeper, whereby the chips are deformed to an even greater extent.

The chip guiding elements10each have a longitudinal rib base11a, wherein the longitudinal rib base11acarries the longitudinal rib11with an edge being formed with the rib flanks14, as shown inFIG.2. The longitudinal rib bases11amake the transition from the rib flanks14to the chip guiding groove9gentler.

The chip guiding structure8further has a plurality of additional chip guiding elements19; of the additional chip guiding elements19, inFIG.1for reasons of clarity, only one of the additional chip guiding elements19is designated19.

FIG.2shows for the additional chip guiding elements19by way of example that the additional chip guiding elements19are formed in the region of the chip guiding groove9, wherein each additional chip guiding element19has a longitudinal rib20having a rib ridge21and rib flanks22which decline at both sides from the rib ridge21, wherein the rib ridge21of each additional chip guiding element19, when viewed in a direction perpendicular to the cutting head plane6, extends in each case radially away from the cutting edge4, wherein each additional chip guiding element19has, when viewed in a direction perpendicular to the cutting head plane6, an end portion23which is free from transverse ribs, wherein each end portion23, when viewed in a direction perpendicular to the cutting head plane6, is opposite the cutting edge4.

FIG.2further shows for the additional chip guiding elements19by way of example that the additional chip guiding elements19each have a longitudinal rib base20a, wherein the longitudinal rib base20acarries the longitudinal rib20with an edge being formed with the rib flanks22. The longitudinal rib bases20amake the transition from the rib flanks22to the chip guiding groove9gentler.

The additional chip guiding elements19and the chip guiding elements10are, when viewed in a direction perpendicular to the cutting head plane6, arranged alternately in an alternating manner with respect to each other in the circumferential direction of the cutting edge4, as shown in particular inFIG.1. The additional chip guiding elements19thus subdivide the region formed between two chip guiding elements10which are adjacent when viewed in a direction perpendicular to the cutting head plane6so that the chips can be supplied to the transverse ribs12with a chip blockage being avoided.

One of the longitudinal ribs20is located, when viewed in a direction perpendicular to the cutting head plane6, centrally on the cutting edge axis7of symmetry, as shown in particular inFIG.1. When feeding parallel with the cutting edge axis7of symmetry, the additional chip guiding element19with the longitudinal rib20which is arranged centrally in this manner ensures that the chips are supplied to the transverse ribs12which are arranged at both sides for this purpose.

In each of the additional chip guiding elements19, the longitudinal rib20has a rib hump24. The rib humps24are in each case arranged and formed, when viewed in a direction perpendicular to the cutting head plane6, at the side of the cutting edge4, wherein the rib humps24in each case protrude from the cutting head plane6. The rib humps24prevent the chips from being able to run off directly via the rib ridges21.

The chip guiding structure8further has a plurality of recesses25at the side of the cutting edge4; of the recesses25, inFIG.1, for reasons of clarity, only two of the recesses25are designated25. The recesses25are in each case formed in pairs of two recesses25, which can also be referred to as a dual formation of the recesses25.

The recesses25, the chip guiding elements20and the additional chip guiding elements19are arranged alternately in an alternating manner when viewed in a direction perpendicular to the cutting head plane6so that in each case between a chip guiding element10and an additional chip guiding element19two recesses25are arranged and formed at the side of the cutting edge4, as shown in particular inFIG.1. The recesses25ensure a pre-deformation of the chips before the chips can slide into the chip guiding groove9and are guided at that location from the rib flanks14to the transverse ribs12.

The chip guiding structure8further has a cutting edge chamfer26. The cutting edge chamfer26has, when viewed in a direction perpendicular to the cutting head plane6, a plurality of V-shaped protuberances27, wherein the V-shaped protuberances27extend in each case radially away from the cutting edge4, are planar and are connected to a rib ridge13in each case with an edge being formed. The rib flanks14consequently decline from the cutting edge chamfer26in each case laterally at both sides in the region of the V-shaped protuberances27, which improves the chip deformation.

InFIG.3, it can be clearly seen that the rib humps24protrude from the cutting head plane6.

InFIG.3, it can further be seen particularly clearly that the transverse ribs12protrude from the cutting head plane6.

The cutting head2has a clearance face28, wherein the clearance face28and the cutting edge chamfer26are connected to each other by the cutting edge4. The clearance face28forms a protuberance29at the side of the additional cutting element19, the longitudinal rib20of which is located centrally on the cutting edge axis7of symmetry.

When viewed in a direction perpendicular to the cutting head plane6, two rib ridges13and rib ridges21which are adjacent to each other have a constant angle α, wherein the angle α is measured at the side of the cutting edge4and is in the range from 20° to 30°, preferably the angle α is 25°; inFIG.1, for reasons of clarity, only an angle α is illustrated and the reference numerals of the rib ridges13and21are indicated inFIG.2by way of example for all the chip guiding elements10or all the additional chip guiding elements19. The angle α in the range from 20° to 30° ensures that the chips of the transverse rib12are better supplied. At an angle α greater than 30°, the chips would escape laterally. At an angle α less than 20°, the chips would run up against each other and thus block the region between the chip guiding elements10and the additional chip guiding elements19in each case.

The cross section which is shown inFIG.4and which is orientated radially with respect to the cutting edge4and can also be referred to as a rib longitudinal section shows for the additional chip guiding elements19by way of example that the longitudinal ribs20are in each case curved in a concave manner between the rib hump24and the central portion15.

The cross section which is shown inFIG.5and which is orientated radially with respect to the cutting edge4, and which can also be referred to as a rib longitudinal section, shows for the chip guiding elements10by way of example that the transverse rib12at the side of the rib ridge13is curved in a convex manner and that the longitudinal rib11at the side of the cutting edge4is curved in a concave manner so that chips which run on the rib ridge13are formed to follow the convex curvature and strike the transverse rib12.

The chip guiding elements10are consequently in the radial rib longitudinal section thereof in the form of a capital letter S, wherein one curve of the capital letter S is formed in the region of the transverse rib12so that the transverse rib12bends outwards, wherein the other curve of the capital letter S is formed in the region of the rib ridge13so that the rib ridge13bends inwards.

FIG.6shows a perspective illustration of the cutting element1, according to which it can be seen that the cutting element1has an additional cutting head200which is constructed in a similar manner to the cutting head2. The additional cutting head200is carried by the shaft3opposite the cutting head1so that, after a rotation of the shaft3which brings the cutting head200into the position of the cutting head2, a feed operation can be continued.

The shaft3has a V-shaped groove30by means of which the cutting element1can be clamped in a holder in a positive-locking manner. The V-shaped groove30consequently extends along the longitudinal extent of the shaft3.

The V-shaped groove30has in the groove base thereof a U-shaped groove31The U-shaped groove31and the V-shaped groove30extend into the central portion15, wherein the U-shaped groove31ensures a coolant supply of the cutting edge4.

The present invention is not limited to the embodiment of the cutting element1as shown inFIGS.1to6. It is also conceivable and possible for the cutting element1to be produced without the additional cutting elements19and/or without the recesses25.

It is further conceivable and also possible for only one of the chip guiding elements10to have the transverse rib12or preferably only two of the chip guiding elements10to have the transverse rib12in each case.