Cutting insert, method of manufacturing the same, tool and machining method using this insert

The invention relates to a cutting insert, in particular an insert, according to the preamble of claim 1, a method for Production of such a cutting insert according to the preamble of Claim 18, a equipped with such a cutting insert A tool according to the preamble of claim 29 and a method for machining a workpiece using a such a cutting board or of such a tool for the Preamble of claim 31st

The movements during the machining process are relative movements between a cutting tool and the workpiece. movements are generated by a machine tool and can be straight, be circular or arbitrarily. The chips are produced when the formed from flank and cutting face cutting wedge after a feed penetrates through the knitting motion in the workpiece.

There are cutting wedges of metallic and nonmetallic materials known, for example, cutting steel, tungsten carbide, ceramic, Mixed ceramics, corundum, silicon carbide, boron carbide, diamond and the like.

In particular, carbide inserts can with a very thin Surface layer of extremely fine-grained carbides or ceramics be provided and thus a significant increase in wear resistance learn. The main coating materials are usually deposited by vacuum evaporation, are TiCN, TiN, Al₂O₃And TiC. are to deposition of the coating materials the PVD, CVD and the Arc-PVD processes known. With the PVD processes can maximum layer thicknesses of about 2 to 5 microns, with the CVD method, maximum layer thicknesses of about 12 to 15 microns and maximum at the Arc-PVD coating thicknesses to about 50 microns can be achieved. Upon engagement of the tool into the workpiece is the cutting material or coating its surface in contact with the workpiece along the cutting face. The Cutting edge undergoes the cutting motion a-wearing Load, which leads to a flattening, the so-called Rake and flank wear. The strain of Surfaces at cutting wedge by pressure and shear forces under the influence of temperature however, is different. A distinction is accordingly different failure modes of the various surface elements, For example, flank wear, crater wear, plastic deformation, notching, Kammrißbildung, fatigue fracture, Ausbröckelung, tool breakage, built-up edge. These types of wear can occur and affect parallel the cutting process and the surface result on Workpiece. In practice, for reasons of economy an abrasive Wear approved. The end of service life of the cutting edge is set as a parameter of passive force, accumulated heat and surface quality. The wear caused by the outbreak of cutting elements is generally defined as end of service life.

The cutting wedges for cost reasons only as small inserts performed to the tool body has many To use service life and to the lowest possible use of expensive cutting materials to achieve. simultaneously in today's machining processes requirements the accuracy of the cutting edges always greater (± 0.01 mm). At the Sintering process is due to the shrinkage, repeat over several batches only with additional retrospective Grinding operations reachable. There have also high demands on the quality of the recordings for the cutting plates be that many insert lifetimes accurate positioning enabling and supporting the interchangeable cutting tips have to. To substitution and attaching the panels must by qualified personnel are carried out, since the cleanliness Seats and the repeatability of the mounting movement positional accuracy the cutting plate affected.

At the cutting edge is in the conventional inserts a Clearance angle necessary. Through a constant feed is in the Workpiece from the cutting edge contour generated continuously in the processing circuit the tool moves. Such a mechanism makes open spaces needed for climb and conventional milling. The lower the proportion of the cutting plate movement at the cutting speed vector is, the less is needed at this kinematic a flank angle. By heating of the workpiece material in the zone behind the cutting edge occurs by thermal expansion to a flaring of the machined workpiece surface. By the spring back of the elastic deformation of the workpiece material by the passive force at the cutting edge, it is advantageous, to have a flank angle. The size of the clearance angle is the ratio of average speed to feed speed and the kinematic motion (external or internal machining, rotating tool or rotating workpiece) affected. At the same cutting parameters takes the free angle required becomes narrower pitch of the tips to. This is advantageously, to achieve lower tool changing times. also is the size of the clearance angle of the cutting edge radius certainly. For the processing must be a reasonable relationship between Nose radius and chip thickness are found. Since the possible effective feed per unit of time during the milling, drilling and spaces the sum of feed / tooth and tooth number / tool is, narrow pitches are desired for economic reasons.

The invention is based on the object, the generic Cutting plate, the generic method, the generic Tool and the generic cutting method in such a way that in a simple manner and with a long service life of the tool or its cutting plate high machining accuracy is achieved on the workpiece.

This object is in the generic insert having the characterizing features of claim 1, in the generic method according to the invention with the characterizing features of claim 18, in the generic Tool according to the invention with the characterizing features of claim 29 and the generic cutting method according to the invention with the characterizing features of Claim 31 dissolved.

In the cutting insert according to the invention the relief angle is at Cutting wedge in the range between 0 ° and about 3 °. Through this low Flank angle which can even be 0 °, in a simple manner achieved a satisfactory treatment result. If the Flank angle 0 °, a cutting surface is formed, which at the Cutting edge connects. With sufficient stabilizing Cutting edge of imprinting in the workpiece surface portion of the cutting insert is reduced to a minimum.

With the inventive method the cutting plate can inexpensively Way can be easily manufactured. On the Insert the chip face and the open space in the form of a applied coating, which is possible in a simple manner. In the the respective coatings cutting materials contained can according to occur during the machining with the cutting plate Loads are selected.

When rotating tool according to the invention are the cutting edges the cutting inserts on the periphery of the tool on a imaginary cylinder jacket or any rotationally symmetric Contour.

When working with the tool according to the invention or the inventive Cutting plate with the open space immediately Following the release of the chip from the workpiece, the exposed Fractured surface smoothed on the workpiece. In this way, in a roughed single operation and settled be. By are smoothing effect occurring when detaching the chip eliminates protrusions in the fracture surface of the workpiece, so that subsequent reworking of the workpiece not required is.

Further features of the invention result from the additional claims, the description and the drawings.

The invention is illustrated with reference to two in the drawings Embodiments explained in more detail. Show it<dl tsize="7"><dt>Fig. 1</dt><dd>a cutting wedge of a tool according to the invention, worn with a chip on a workpiece becomes,</dd><dt>FIG. 2</dt><dd>in an enlarged view of the cutting area of ​​the wedge inventive tool,</dd><dt>Fig. 3</dt><dd>in a representation corresponding to FIG. 2, a second Embodiment of a tool according to the invention.</dd></dl>

at least, the tool is not shown in detail, has a Insert 1, which in a known manner on a tool carrier is attached. The insert 1 has a cutting wedge 2, of a Rake face 3 and an open space 4 is provided. The wedge angle 5 (Fig. 1) is in the range between about 70 ° and 95 ° and is preferably 90 °. The clearance angle at the cutting wedge 2 is in the range between 0 ° and about 3 °, preferably at 0 °.

With the insert 1, a workpiece 6 is machined. Here, a chip is 7 lifted off the workpiece. 6

Since the rake face 3 and the flank face 4 during the cutting Machining of the workpiece 6 are claimed differently, associated with different materials these two surfaces. The flank face 4 is formed by at least one coating 8 Insert 1 formed. The coating 8 has a thickness of 9 more than at least about 0.02 mm. Instead of a layer may also be provided a plurality of thin layers which the forming layer. 8

The rake face 3 has a coating 10 and has a larger Mass fraction than the coating 8 of the flank 4. The Coating 10 is made of impact resistant material with a wear-reducing surface with low roughness, insulating Properties and a low coefficient of friction. This ensures that the clamping surface 3 only a little wear subject.

Since the open space 4 in use of the tool a stronger influence on the workpiece quality than the rake face 3, the Free surface 4 of a cutting material or a cutting material composition, the higher abrasion resistance and a higher hardness than the Cutting material or the cutting material combination of the coating 10 the rake face 3 has. Thus, these two areas 3 and 4 optimally to the stress during the machining be adapted of the work. 6 The material combinations on Cutting wedge 2 can be improved because the respective different Stresses on the rake face 3 and the flank face 4 are each tailored cutting materials or cutting material mixtures assigned. In particular, the flank wear, of the surface quality and the dimensional accuracy of the workpiece 6 determined can be reduced, whereby the quality and / or quantity of producible with the tip 1 workpieces 6 can be increased. By a higher temperature resistance the cutting, the speed of action between increased the tool and the workpiece 6, thereby forming a Productivity gain is achieved.

The rake angle 11 (Fig. 1) of the indexable insert 1 is in the range of about -10 ° to about + 15 °. The open space has a 4 on the cutting edge 12 adjoining portion 13 to the rake face 3 Clearance angle between about 0 ° and 3 °. The region 13 is then in an open space area 14, which has a larger clearance angle 15 has, of the preparation is ch between about 5 ° and 10 °.

On the free surface 4 a very thick wear resistant layer 8 applied, which by simple Umfangsabrichten, similar to dressing a grinding wheel, is processed, whereby a highly accurate Tool is generated. After application of the coating 8 before the first use of the insert 1 and the Tool on the flank 4 a consciously insert wear anticipated. The coating 8 has a binder 16, in the wear-resistant elements are embedded 17th They consist of individual CBN monocrystals or similar hard material particles, such as Al₂O₃ (Corundum), silicon nitride, sapphire, natural or artificial diamond crystals and the same. The monocrystalline cutting elements 17 have a diameter or cross-sectional width in the Order of about 0.05 mm. The binder allows 16 over the lifetime of the insert 1, a sufficient fastening CBN monocrystals 17 occur during the processing of Workpiece 6 on load impacts, the cutting elements 17 can or their cutting edges avoid elastic. The CBN elements 17 are provided only on those active surfaces of the cutting wedge 2, learn the low load impacts. Doing, the CBN elements 17 a great wear resistance and high hot hardness show. At the transition between the shock-loaded clamping surface 3 and the open space 4 there is a plurality of such elements CBN 17, so that after wear of the one element 17 immediately following element for further processing is ready.

The from the CBN mono elements 17 and the binder 16 formed Matrix has a sufficiently high layer thickness, the advantageous is greater than 50 microns and which permits dressing. With him, the sintering accuracy, the mounting accuracy and the Insert seat accuracy in proportion to their respective cost shares be reduced. As the binder 16, for example, comes in Nickel Consideration.

Each CBN element 17 has a cutting edge. The stochastic Probability of failure of a cutting edge as a result of of several CBN elements 17 formed on the cutting edge 12 subsequent area is increased so that a longer service life with can be driven to the tool. If the insert 1 to the open space 4 in the manner described by Umfangsabrichten edited by the machining-specific mechanisms resulting Abdrängkräfte in this anticipated Insert wear on the flank 4 by this particular Surface design incorporated. The cutting edge 12 is sufficiently supported by layer matrix, the wear-resistant CBN elements 17 of the free surface coating 8 a very form low percentage.

With the tool and its inserts 1 is already in Lifting the Schruppspäne 7 a very good workpiece surface reached. This can be a significant process chain shortening to accomplish. By incorporated in the coating 8 of the open space 4 wear-resistant elements 17 with the insert 1 the Schruppspan 7 with a geometrically defined cutting edge and simultaneously a chipping similar to grinding with geome metrically undefined cutting edges performed. The geometrically certain cutting edges are the edges of the monocrystalline wear-resistant elements 17 formed. The essential Werkstückstoffabtrag only of the geometrically defined cutting or its cutting edge 12 are performed.

The wear-resistant members 17 are preferably made of CBN, which is a highly wear-resistant hot hard cutting material is. For this but members are also ceramic materials, diamond and the like into consideration. The embedded in the tie 16 wear-resistant Elements 17 cause an abrasive surface contact between the cutting surface 4 and the workpiece surface 18. As a result, Asperities are smoothed. In this way, the Workpiece 6 roughed in a single operation and settled will. There are no longer two operations for the coarse and the Finishing necessary.

The free space required by the indexable insert 1 is as small as possible kept. There is even a cutting surface in the form of the surface segment 13 a body of rotation allowed that connects to the cutting edge 12th The flank face 4 is a very low percentage designed. This is achieved, that at a sufficient stabilization of the cutting edge 12 of the on the workpiece surface 18 pressing part of the insert 1 a minimum. This is achieved by the individual monocrystalline elements 17, which are embedded in the binder sixteenth The individual grains 17 form with their lying in the surface Edges the geometrically undefined cutting edges, which limited Dimensions a machining is possible. These edges the workpiece surface 18, immediately following the removal chip 17 is smoothed.

Despite these individual wear-resistant elements 17 is a sharp cutting edge 12 by the described dressing after the complete assembly of the tool with the Inserts 1 reached. The resulting risk of cutting edge chipping is determined by the redundancy of the cutting edge 12 forming wear-resistant elements 17 encounters. Within the range 13 (Fig. 1) of the free surface 4 form the one behind the other wear-resistant elements 17 a cutting surface. Since these wear-resistant Elements 17 are on the same tool radius, can a subsequent element 17 a fancy to the cutting edge 12 Replace element 17th Since the wear-resistant elements 17 are included in the binder 16, have the wear-resistant elements 17 is a shock and vibration cushioning and damping Effect, whereby the tendency to break is reduced.

The thickness of the coating 9 8 the free surface 4 may be greater than be 0.02 mm. This large layer thickness allows greater Elasticity of the cutting edge 12 forming the wear-resistant elements 17. By coating with different grains or can deposition times an accurate absolute measurement of the cutting edge 12 be achieved by the plurality of the different wear resistant Elements 17 is formed. The low percentage of Free surface 4, 13, vibrations between the workpiece 6 and the tool steamed.

This fitted with the inserts 1 tool allows a cutting method, wherein the cutting speed in the range between the turning, milling and grinding speeds is, therefore, in the range between about 100 m / min and 2000 m / min. Depending on the machining task in the coarse or fine cutting, the Cutting speed and the feed by the relative movement between the workpiece 6 and the tool coordinated.

, a short between the cutting edge 12 and the free surface 4 flat or curved cutting surface be present. is shown in FIG. 1 the short flat cutting surface 13 is shown. Due to the described Wear anticipation by dressing the flank 4 higher machining accuracy of the insert 1 is achieved. The flank face 4 is composed of a plurality of geometric undefined cutting edges defined by the edges of wear-resistant Elements 17 are formed. However, it is also possible that the clearance face 4 of a plurality of defined cutting edges consists.

The cutting wedge 2 and the insert 1 can be used as wafer by sintering from different cutting materials or cutting material mixtures getting produced.

The tool or the insert 1 consists of various Materials, which according to the stress during processing to be chosen. These materials can in layers be applied, wherein the various layers of material different may have thickness. The insert 1 has a Basic body, which in the described manner on the rake face 3 and at the flank face 4 are each at least one coating 10 or 8. can on the rake face 3 and the flank 4 both on the type and the number of different coatings be provided. These coatings 8, 10 can in turn consist of several individual layers. The coatings 8, 10 are advantageously deposited on the base body. For this, the PVD (physical vapor deposit), the CVD (chemical vapor deposition) and known the arc PVD process. These methods are, since they are known, no further explanation. With the PVD method can coatings to a thickness between about 2 and 5 microns, the CVD process coatings in a thickness of about 12 to 15 .mu.m and at Arc-PVD coatings in a thickness be made up to about 50 microns. Depending on the desired thickness the coatings 8 and 10, is one of these methods advantageously used.

However, it is also possible for the different layers of the coatings 8 and 10 of cutting material or cutting material mixtures by soldering or by electroplating together. These different layers of cutting material or cutting material mixtures can by flame, laser spraying or by plasma deposition advantageously be interconnected.

Fig. 3 shows an embodiment in which the coating 8 on with the wear-resistant elements 17 a thin coating 21 provided is. It consists of TiC, TiN, Al₂O₃, TiCN, etc. and is one of the methods described for the coating 8 applied.

The inserts 1 can be used in tools that be used for turning, milling, broaching or rotary milling. The individual inserts 1 are on the periphery of this tool either on a cylinder jacket or any rotationally symmetric Contour.

Are the tools with the inserts 1 as turning tools used, the open areas 4 or its free surface sections can 13 on the circumference of the tool form a polygon. The relief section 13 can except by the described loops also be processed by laser or other dressing. A sharpening of this section 13 is possible. For the production the open space portion 13 by dressing or sharpening can All known methods of grinding technology to be used, to deliberately remove the layer constituents in the open space. 4 Consists the coating 8 on the surface 4 free in the described , From the wear-resistant elements 17, the elastic in the Binder 16 is embedded, a multitude of geometric undefined cutting edges. They also practice at cutting speeds according to a milling a smoothing effect on the machined workpiece surface 18 from. How. Of Figures 1 and 2 shows is through the insert 1 with the cutting wedge 2 separated from the workpiece 6 of clamping. 7 With this chip formation produced on the workpiece 6 by a leading crack 19, of a rough Fracture surface 20 forms. This rough fracture surface 20 is determined by the subsequent relief section 13 with its variety of geometric smoothed indefinite cutting or polished or sanded. Therefore after roughing is finishing of the workpiece 6 is no longer necessary. At the cutting edge 12 produced an antibody directed against the workpiece 6 pressure, so that the Workpiece is loaded in this area inward. Since the wear-resistant Elements 17 embedded in the elastic tie 16 are, can the respective loaded workpiece area behind the Cutting edge 12 or behind the respective wear resistant elements 17 spring back. The following wear-resistant elements 17 can then these sprung back workpiece area in as described flatten and possibly even grind. A stocked with the described inserts 1 Tool, the workpiece 6 in one operation very closely and edit with low cost. As in the inserts 1 the manner described by the dressing a wear anticipation is achieved, can easily the high machining accuracy be achieved. When wear anticipation by dressing the open space in the area 13 is the well-known Life characteristic of the insert utilized. After 50% of the radial wear of the insert 1 has only 30% of their achieved lifetime. Due to the significantly lower cost of Tip 1, the waiver of up to 30% of the service life be overcompensated. The radius of the cutting edge 12 can be very be kept small, whereby the use of the insert 1 also a correspondingly small Abdrängbelastung the tip 1 is achieved. The dressing can be an extremely sharp Cutting edge achieve 12, whereby the machined workpiece surface 18 has a high accuracy. By abrasive surface contact between the region 13 of the flank 4 of the insert 1 and the workpiece surface 18 are also smoothed the asperities, whereby the machining accuracy is further increased.

In addition, the machining accuracy can additionally be increased by the fact that the machine rigidity mechanically or is increased through control corrections. Also one Increasing the average speed during the cutting process leads to increased machining accuracy. This is also being Avoid transmission relief through several the engaged Inserts 1 at. Moreover, the position accuracy the inserts can be increased for the tool center. The Inserts 1 are now individually with an accuracy of ± 5 microns or ground in series. The board seats of the tool by tuning to an accuracy of up to ± 10 microns Voted. The intelligent combination of these measures, adapted to the respective application (turning, milling, rotary milling, Boring, broaching, vertebrae, and the like), the cutting Process in terms of accuracy and efficiency compared be substantially improved with the known tools.

The simplest and least expensive solution is the turning plate 1 so as to form that the clearance angle at the cutting part 2 between 0 and 3 °, preferably at 0 °. This clearance angle is achieved by dressing the open space 4 in the region. 13 Only through this measure is compared to conventional turning or Inserts 1 a substantially improved accuracy and efficiency achieved. In addition, the previously described further measures are useful combined, thereby the machining accuracy and efficiency even further be improved.

The wear-resistant elements 17, which preferably CBN monocrystals are subject only to those active surfaces of the Insert 1 provided that experienced low load impacts, but with a large wear resistance and high hot hardness must demonstrate. This effective area is the open space 4. The transition between the impact loaded rake face 3 and the CBN crystals seated surface 13 is by a redundancy of the Workpiece surface determining CBN grains marked. This coating 8 is not designed as a fine-grained sintered cutting edge 12, but consists of individual single crystals, which have sufficient have Bewegungsmoglichkeit to today. The binder 16 allows an elastic integration of the CBN grains 17 and allows on the life of the insert 1 sufficient Fixing the CBN grains 17 Under load surges can Cutting edges of the respective CBN grains 17 in the described Way to dodge. After dressing forms the elastic Matrix by wear the low percentage of the region 13 the open space. 4