The invention relates to a rotary cutting tool, in particular a milling tool, boring tool or a reamer, with a metallic base tool body with at least one preferably helical flute, preferably with a pair of flutes, wherein a cutting element or cutting insert of an ultra-hard cutting material such as polycrystalline diamond (PKD; Engl. PCD) or polycrystalline, cubic boron nitride (PKBN; Engl. PCBN) for forming a helically running cutting edge is associated with the at least one flute and is connected such as soldered to the base tool body, and relates to a method of manufacturing a rotary cutting tool.
A rotary cutting tool and a method of manufacturing such a tool is described in DE 689 11 468 T2. The known rotary cutting tool comprises a metallic base tool body helically provided with flutes and comprises a polycrystalline diamond film that covers at least a part of a cutting surface of the base metallic tool body provided with flutes. The polycrystalline diamond film has a thickness in the range of 50 to 300 μm. According to this technology the polycrystalline diamond film is manufactured by being vaporized onto a bolt of molybdenum or something similar. The molybdenum substrate is introduced into hot aqua regia and dissolved in order to allow only the helical diamond band to stand. This diamond film is then hard-soldered onto the cutting surface of the flute of the cutting tool with a hard-solder agent. Subsequently, the flank surface is polished in order to form a sharp cutting edge.
The method for manufacturing the helical diamond film is rather expensive. Also, the service life of the rotary cutting tool is reduced since the diamond film is very thin.
DE 691 04 363 T2 relates to a rotary cutting tool with cutting edges of hard material extending helically along its length and comprising a rotary cutting tool blank with at least one pair of helical flutes in the side walls of the blank and with a hard material inside the flutes. The hard material is selected from a group consisting of polycrystalline diamond and polycrystalline, cubic boron nitride. The hard material has a cutting edge formed along a front edge, wherein the polycrystalline, hard material is formed in situ in the flutes. The manufacturing method is expensive and the longitudinal extension of the helical cutting edges is limited to 10 mm to 12 mm.
Starting from the above, the present invention has the basic problem of further developing a rotary cutting tool of the initially cited type and a method for manufacturing such a tool in such a manner that the service life is increased and the manufacture is simplified.
The problem is solved in accordance with the invention, among other things, in that the cutting element is constructed as a one-part diamond body in the form of a section of a solid body or of a similar body or that the cutting element is constructed of several diamond segments of a section of a solid body or of similar ones, that the cutting element is received in a receptacle constructed along the flute, wherein the helically curved cutting edge is constructed in the diamond body or the diamond segments in a material-removing manner
The cutting insert or the cutting element is preferably constructed as at least one diamond segment or diamond body that rests with at least one straight surface against a stop constructed along the flute, wherein the helically curved cutting edge is introduced in a material-removing manner in a surface opposite and/or bordering the straight surface.
The at least one diamond segment of the diamond body is preferably constructed as a section of a solid body in the form of a plate-shaped or disk-shaped solid PKD blank or a solid PKBN blank, wherein the blanks have a layer thickness D in the range of 0.3 mm≦D≦5 mm, preferably 1 mm≦D≦4 mm, especially preferably D=2 mm.
The diamond body forming the cutting element can also be disposed as a solid PKD or solid PKBN on a base body such as a hard metallic carrier or between two base bodies such as hard metallic carriers as a sandwich PKD blank or sandwich PKBN blank, wherein the cutting elements are cut out of the blank.
The at least one diamond body can also be constructed as a CVD thin layer, CVD thick layer or mono-diamond onto the base tool body.
Another preferred embodiment is distinguished in that the diamond body or the diamond segment is constructed as a preferably rod-shaped, annular segment. The annular segment is cut out of the plate-shaped or disk-shaped solid PKD blank, solid PCBN blank, sandwich PKD blank or sandwich PCBN blank and preferably has a height H in the range of 0.1 mm≦H≦10 mm, preferably 2 mm≦H≦4 mm, and a length L1 in the range of 1 mm≦L1≦120 mm, preferably L1=30 mm.
The stop is preferably part of a receptacle constructed in an L-shape or U-shape and miming in a straight line or helically that is introduced such as ground into the base tool body in a material-removing manner.
In an embodiment in which the L-shaped or U-shaped receptacle runs straight at an angle α relative to the longitudinal axis of the tool the diamond body can be constructed as a planar annular segment, wherein a curved inner edge rests on a lower shank or section of the L-shaped or U-shaped receptacle and a curved outer edge forms a radial outer surface.
Furthermore, it is provided that the spiral angle α is in a range of 1°≦α≦30 and that the spiral angle α is in a range of 5°≦α≦50° in an embodiment of the several individual diamond segments disposed successively in the longitudinal direction.
Another preferred embodiment is distinguished in that the cutting insert or the cutting element is constructed from a plurality of preferably plate-shaped diamond segments, wherein the plurality of diamond segments is disposed along a helically running stop or a helically running receptacle and is connected such as soldered to the base tool body. In this embodiment the helically running cutting edge is constructed by a plurality of cutting edge segments of the individual diamond segments.
The helical cutting edge is preferably constructed from a plurality of cutting edge sections of the individual diamond segments. A cutting surface and also a free surface are preferably formed that are helically curved.
Furthermore, the cutting element has a round bevel, wherein the round bevel has a width B that is constant, smaller or becomes larger over the longitudinal extension of the cutting element.
Furthermore, the problem is solved by a method for manufacturing a rotary cutting tool with a cutting element comprising an ultra-hard cutting material such as polycrystalline diamond (PKD) or polycrystalline, cubic boron nitride (PKBN; PCBN) that preferably has the following steps:
wherein the cutting insert is preferably constructed as a diamond segment with an oversize in the radial and/or circumferential direction and is connected to the base tool body, and wherein a cutting edge running helically or in a spiral in a radial and/or circumferential direction is constructed by removing material from the diamond segment connected to the base tool body.
Alternatively, one-part diamond bodies in the form of a section of a solid body or multiple diamond segments each in the form of a section of a solid body can be used as cutting element and fastened in the receptacle in such a manner that the cutting element has an oversize opposite a theoretical size in the radial and/or circumferential direction, and that a helically running cutting edge is formed by removing material in the radial and/or circumferential direction from the cutting element connected to the base tool body.
It is especially preferred that the cutting element is constructed as one-part diamond body or of several diamond segments each in the form of a section of a solid body and is fastened in the receptacle in such a manner that the cutting element has an oversize in the radial and/or circumferential direction opposite a theoretical size and that a helically running cutting edge is formed by material removal in the radial and/or circumferential direction from the cutting element connected to the base tool body.
The cutting insert or the cutting element is preferably constructed as at least one diamond segment or diamond body that rests with at least one straight surface against a stop constructed along the flute, wherein the helically curved cutting edge is introduced in a material-removing manner in a surface comprising an oversize opposite or bordering on the straight surface in the radial and/or circumferential direction.
A plate-shaped or disk-shaped solid PKD blank or solid PCBN blank can be used as the solid body from which the one-part diamond bodies or the diamond segments are cut out and/or a blank such as a sandwich PKD or sandwich PCBN is used as the solid body, wherein the diamond body is disposed as a solid PKD or solid PKBN on a base body such as a hard metal carrier or between two base bodies such as hard metal carriers, and wherein the cutting elements are cut out of the blank.
The at least one diamond segment or the diamond body is preferably constructed from a plate-shaped or disk-shaped solid PKD blank, solid PCBN blank, wherein the blanks have a layer thickness D in the range of 0.3 mm≦D≦5 mm, preferably 1 mm<D≦4 mm, especially preferably D=2 mm. The diamond body can also be a component of a plate-shaped or disk-shaped sandwich PKD blank or a sandwich PKBN blank, wherein the diamond body is disposed as a solid PKD or solid PKBN on a base body such as a hard metal carrier or between the base bodies such as hard metal carriers. The at least one diamond body can also be applied as a CVD thin layer, CVD thick layer or mono-diamond onto the base tool body.
If the diamond body or the diamond segments is/are manufactured from a solid PKD blank or solid PKBN blank, the diamond body or the diamond segments are preferably connected by vacuum soldering to the base tool body. When constructed as a sandwich PKD blank or sandwich PCBN blank, the metallic bottom of the sandwich structure can preferably be hard-soldered or laser-welded.
The diamond segments or the diamond body is/are preferably cut by a wire erosion method or laser method from a plate-shaped or disk-shaped solid PKD blank or solid PCBN blank, sandwich PKD blank or sandwich PCBN blank.
Even the material removal for manufacturing the spiral cutting edge and/or cutting surface takes place by an eroding method, wherein the diamond segments of the diamond body connected to the base tool body is/are conducted past the rotating, disk -shaped carbon electrode in a spiral movement preferably positioned at an angle α in accordance with the spiral to the longitudinal axis of the tool.
Alternatively, the material removal can take place by laser methods.
In the removal of material the width of a round bevel, i.e., the circumferential extent of the diamond body or of the circumferential segments in the longitudinal direction of the spiral cutting edge can be, for example, approximately 2 mm to approximately 0.8 mm. The width B of the round bevel can be constant or increase or decrease in the longitudinal direction.
The spiral angle α can be, in an embodiment with an annular, segmental diamond body, in the range of 1°<α<30° and in an embodiment with individual diamond segments successively disposed in the longitudinal direction in a range of 5°<α<50°.
Other details, advantages and features of the invention result not only from the claims, the features to be gathered from them by themselves and/or in combination but also from the following description of preferred exemplary embodiments to be gathered from the drawings.
In the drawings:
a shows a perspective detailed view of a diamond segment,
b shows a perspective view of a PKD blank with a cut-out cutting element,
The base tool body 12 comprises a pair of helical flutes 16, 18 with an L-shaped or U-shaped receptacle 20, 22 along whose course a one-part cutting element, designated in the following as cutting insert 24, 26, consisting of ultra-hard cutting material such as polycrystalline diamond (PKD) or polycrystalline, cubic boron nitride (PKBN) in which a helically curved cutting edge 28, 30 is introduced by material removal.
The diamond body 24 in the form of the circular arc segment is shown in a perspective view in
The helically curved cutting edge 30 is introduced in a material-removing manner, preferably ground by an eroding method or laser method into the straight lateral surface (34 (cutting surface) on the flute side and into the radial outer surface (36 (round bevel) of the diamond body 24. The flute-side lateral surface 34 has a constant cutting angle over the entire length.
According to the present invention the cutting insert 24, 26 is constructed as a plate-shaped, one-part diamond body in the form of a section of a solid body 35 and clamping a plane, which body is shown in
A method for manufacturing the rotary cutting tool in accordance with the invention is distinguished in that the cutting insert 24, 26 is cut out of the plate -shaped blank 35 with a radial and circumferential oversize opposite a theoretical size as a plate -shaped diamond body clamping a plane, and is connected to the tool body. The helical cutting edge is then introduced into the flute-side lateral surface 34 and radial outer surface 36 of the diamond body in a material-removing manner preferably by an electroerosive eroding method or laser method by material removal in the diamond body connected to the base tool body. The base tool body executing a spiral movement is moved here with a cutting edge along a rotating electrode such as a carbon electrode aligned at an angle to the longitudinal axis of the base tool body.
The diamond bodies 24, 26 of polycrystalline material such as solid PKD, solid PKBN can be cut out of the plate or disk 35 by a wire eroding method. The diamond bodies can have a layer thickness D in the range of 0.3 mm to 4 mm, preferably D=2 mm. Furthermore, the diamond body can have a length L in the range of 5 mm≦L≦50 mm.
The angle α can have angles in the range of 5°≦α≦30°, preferably α=20° in a one-piece or one-part embodiment of the diamond body. The blanks of the diamond bodies can have a radial extension or height H in the range of 2mm ≦H≦4 mm.
The
The diamond segments 56, 58 with a radial oversize relative to a theoretical size are subsequently processed by an eroding method or laser method, wherein a spiral surface 60, 62 (round bevel) is formed with a spiral cutting edge 64, 66.
In this embodiment the radial outer surface 60 (round bevel) and also the cutting surface 64, 66 is worked with a preferably positive cutting surface angle by the eroding method or laser method, wherein the round bevel in the form of the radial outer surface 60, 62 and also a cutting breast or cutting surface in the form of the cutting surface 64, 66 are worked. During this time the surfaces 60, 62 are converted into a circumferential surface of the base tool body 42 and the cutting surface is 64, 66 into a surface clamped by the flutes 44, 46, preferably by an electroerosive eroding method or laser method, preferably by an electroerosive eroding or laser method.
The spiral cutting jacket edge or cutting edge is preferably introduced by an eroding method with removal of material. Alternatively, a laser method can also be used.
According to
Number | Date | Country | Kind |
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102013111090.8 | Oct 2013 | DE | national |
102014104781.8 | Apr 2014 | DE | national |