EP2129483A1

EP2129483A1 - Cutter support and cutter head

Info

Publication number: EP2129483A1
Application number: EP08706784A
Authority: EP
Inventors: Markus Heinloth; Ralf KLÖTZER; Helmut Klein
Original assignee: Kennametal Inc
Current assignee: Kennametal Inc
Priority date: 2007-03-08
Filing date: 2008-01-22
Publication date: 2009-12-09
Also published as: US8297890B2; DE102007011330A1; CN101626858B; RU2009137141A; RU2425735C2; CN101626858A; MX2009009259A; KR20090122939A; WO2008106914A1; JP2010520073A; US20100104383A1; JP5230657B2; CA2678627A1; BRPI0808468A2

Abstract

The invention relates to a cutter support (11) for fastening to a cutter head, comprising a shaft-like pin (11) and a head, having a soldered-in cutter (12) with a minor cutting edge formed by a face (27) and a free surface (28). According to the invention the minor cutting edge has a rounded area (25), the radius of which continuously increases from a minor cutting edge end (25a) at least to the cutting edge center, or to the other minor cutting edge end (25b).

Description

Cutter carrier and milling cutter head

The invention relates to a blade carrier for attachment to a Fräsmesserkopf, consisting of a shaft-shaped pin and a head with soldered cutting edge with a side edge formed by a rake face and an open space.

The invention further relates to a milling cutter head for orthogonal rotary milling with eccentric tool adjustment, in particular for fine milling of bearings of a crank or camshaft with at least two, preferably three eccentrically arranged cutting carriers of the aforementioned type.

A Fräsmesserkopf of the type mentioned is known in principle from DE 40 03 862. The recesses for the blade carrier extend in the blade head described therein from the one end face of its base parallel to the axis of rotation and at a distance from the circumference, the cutting edges of the inserts used projecting only slightly beyond the end face of the base body. Furthermore, the axes of the serving for bracing round wedges each skewed to the axes of the cutting plates supporting cutting plate carrier. Finally, in each case another round wedge with differential screw for axial adjustment of each cutting plate is provided and arranged in a recess which extends radially inwardly from the circumference of the base body. For axial adjustment and radially outward bracing geometrically equal round wedges are used. As an advantage of this cutter head is highlighted that due to the position of the cutting plate carrier receiving recesses parallel to the axis of rotation of the body only radially directed centrifugal forces occur without axial components. These forces can be well intercepted, because the recesses are not located directly on the circumference of the body, but radially inwardly at a distance from the circumference. The knife head is therefore also suitable for extremely high speeds and the centrifugal forces occurring then. Advantageously, a fine adjustment of the cutting elements in the axial direction without interference with radial components is possible. While in the prior art, crankshafts for cars have been subjected to finish machining by grinding or belt grinding, wherein the grinding has been carried out by the use of cooling lubricants, with the development of suitable milling tools, the grinding of the crankshafts could be replaced by milling processes. Due to the design of the crankshaft, an orthogonal rotary milling with eccentric tool adjustment without axial feed is used. In this case, the tool performs a lowering movement, due to which the shape design of the bearing seats is generated exclusively by the tool cutting edge. In this case, the tool must be adjusted to the workpiece so that it is ensured that during the engagement of the minor cutting the entire apex line of the bearing seat is covered. The bearing seat diameter to be manufactured is generated via this vertex line. Due to the process, middle regions of the secondary cutting edge are engaged longer than other regions. This causes the cutting edge in the middle area to show a higher level of wear than in the outer areas.

Further details about orthogonal rotary milling are described, for example, in DE 10 2004 022 360 A1. However, orthogonal rotary milling with eccentric tool adjustment without axial feed has a decisive disadvantage. Due to the fact that the tool cutting edge carries out a lowering operation in this method, the smallest cutting errors or the tool wear immediately have a negative effect on the shape and surface quality to be achieved. Above all, the different forms of tool wear leads to an early form deviation.

Due to a lack of axial feed movement, a correction of the occurring tool wear over the tool feed is just as impossible as possible in other methods possible changes in the path movements of the tools. It is an object of the present invention to eliminate the aforementioned disadvantages, in particular to find a cutting edge education, which simultaneously ensure a dimensionally accurate workpiece machining and the longest possible life.

A further object of the present invention is to specify a suitable milling cutter head for this purpose.

The first object is achieved by a blade carrier according to claim 1, whose secondary cutting edge according to the invention has a rounding, the radius of which increases continuously from one minor cutting edge end at least to the cutting edge center or to the other minor cutting edge end. Thus, this embodiment includes both blade carriers having a minor cutting edge whose minor cutting edge radius continuously increases from one end from a minimum value to the maximum value at the other end of the minor cutting edge, and those embodiments in which the radius continuously increases from a cutting edge corner to the cutting edge center and then to the end of the secondary cutting edge in turn continuously decreases. In the former case results in a single wedge-shaped rounding section, in the second case, there are two wedges, each of which extends from a cutting edge end to the cutting edge center.

In the case of straight ground cutting edges known from the prior art, it has been found that in the center of the cutting edge and in the region lying on both sides there is a high initial wear, ie a large free surface wear. This forms due to the process at the location of the cutting edge, which has the longest contact time with the workpiece. In adjacent areas, which are in shorter contact times with the workpiece, in particular a crankshaft, the wear on the free surface is lower. Further investigations have shown that with straight cutting edges, a steadily increasing open space initially sets itself apart over a relatively long period of time. After expiration of this degressive wear behavior, the flank wear remains constant in a so-called linear wear region over a relatively longer period of time, before a significant wear reinforcement occurs in a progressive wear area, which renders the tool unusable.

A cutting edge rounding of the type according to the invention allows a rounding of the cutting edge with a small radius in the region of the greatest wear and a rounding with a large radius in the region of lower wear. This geometrical configuration effectively counteracts the blade offset, which occurs as a result of the blade wear.

Practically, cutting edge rounding can be made by brushing, where areas where a cutting edge rounding with a larger radius of curvature is to be created are brushed longer and at higher pressure than those areas where the radius of curvature should be small.

Preferred embodiments of said blade carrier are described in subclaims 2 to 10.

Thus, the minimum radius at a cutting edge should differ from the maximum radius of curvature by a maximum of 6 μm, preferably a maximum of 5 μm.

Optimal are fillet widths, d. H. Widths of the rounded edge, considered perpendicular to the cutting edge profile, which go back to 0 mm at one end of the cutting edge.

According to a further embodiment of the invention, a bevel is arranged on the free surface, which has the rounding, ie that the chamfer has a smaller bevel radius at the outer minor cutting edge ends than in the middle of the minor cutting edge or at the other end, depending on whether a simple wedge-shaped Kegelfasenausbildung or a double cone chase to be generated. Preferably, the width of the chamfer runs at a Nebenschneidkantenende to 0 mm, further preferably continuously. The maximum chamfer width is 10 microns, especially a maximum of 4 microns. The chamfer width should decrease continuously to 0mm, especially on both sides from the secondary cutting edge center. Preferably, the cutting edge or bevel is rounded by means of a breast polishing machine, in particular with a joint angle of 89.5 ° to 90 ° to the axis of rotation of the tool carrier convex ground.

According to a further embodiment of the invention, the smallest radius of the convexly ground flank or cutting edge region is 800 mm. Clearance angle of the cutter carrier are preferably at 10 ° ± 2 °.

To solve the problem, a Fräsmesserkopf according to claim 11 or 12 is also proposed. According to the invention, in the milling cutter head with a plurality of cutter carriers of the aforementioned type, the radius of the cutting edge rounding at the cutting edge end, which writes a smaller circle with rotating Fräsmesserkopf, smaller than the radius of the Schneidkantenverrundung, which describes a large circle. Alternatively, a cutter carrier is used which has a rounded chamfer with a chamfer width decreasing outwards to 0 mm, the chamfer width in each case rising from the end of the minor cutting edge to the cutting edge center up to a maximum value. At the outer minor cutting edge corners, the radius of the bevel fillet is minimal and grows toward the cutting edge center toward a larger cone nose radius. Such a edge-prepared cutting edge has an edge stabilization in the region of maximum wear, which effectively counteracts the otherwise usual cutting edge offset as a result of the wear.

Further embodiments and advantages will be discussed below with reference to the drawings. Show it:

Fig. 1 is a perspective view of a Fräsmesserkopfes with

3 blade carriers,

2 shows a wire-model-like representation of the milling cutter head according to FIG. 1, FIG. Fig. 3 is a longitudinal cross section through a Fräsmesserkopf without

Cutting carrier

4 is a side view of a blade carrier,

5 is a schematic diagram of the relative position of a blade carrier to a clamping piece and a wedge body for axial adjustment,

6 is another side view of the cutter carrier,

7 is a partial enlargement of the area "B",

8 is another side view of the cutter carrier,

9 is an enlarged detail of the area "A",

10 is a plan view of the cutting head of FIG. 9,

Fig. 11 is a schematic wear curve and

Fig. 12 is a schematic representation of another embodiment of a

Chamfering or cutting edge rounding.

The milling cutter head shown in FIGS. 1 to 3 consists essentially of a base body 10, in which three blade carriers 11 are soldered to each with soldered cutting edges 12. The blade carriers 11 are each inserted in parallel to the longitudinal axis 13 arranged bores 22 (see FIG. 3). Further bores in the main body 10 are provided substantially in the radial direction or slightly inclined there, in which wedge bodies 14 are arranged, which are displaceable in the radial direction via an adjusting screw 15, preferably a double-threaded screw. As can be seen from FIG. 5, the wedge bodies 14 have wedge surfaces 16, which run obliquely to the radial plane of the base body, so that during a radial movement of the wedge body 14, the blade carrier 11 is displaceable along its longitudinal axis, ie in the axial direction. For clamping the blade carrier, the clamping piece 18, which is centrally located and has three clamping surfaces 19, which bear against corresponding clamping surfaces of the blade carrier 11. The clamping piece 18 can be fixed by means of a screw 21, which is preferably designed as a double-threaded screw. The clamping piece 18 is used in the illustrated case for the fixation of three blade carriers 11, each having a flat surface 20. Due to the formation of the clamping piece 18 and the arrangement of the clamping surfaces 19 in a triangle shape, an exact alignment of the blades 12 and the blade carrier 11 is achieved at an angle of 120 ° to each other (see Fig. 1). Each blade carrier 11 can be adjusted axially via a circular wedge and the associated screw 15. For the axis-parallel alignment of the blade carrier and thus the cutting serve the holes 22. The surface 23 serves to ensure that there is no line contact between the blade carrier 11 and bore 22. As shown in Fig. 4, the cutter support 11 also has an inclined surface 24, the inclination of which corresponds to the inclination of a surface 19 of the clamping piece.

Alternatively, it is possible to use an outer clamping ring in conjunction with an axially centrally arranged clamping piece, between which the blade carriers 11 can be fixed, instead of the precisely fitting holes. The clamping ring is then screwed or shrunk onto the base body 10.

Fig. 7, which shows an enlarged detail of the area B of the soldered blade 12, it can be seen that the free surface 28 is disposed at a clearance angle of 10 °. The Vorverschleißfase designated 29 is a rounded chamfer, which has the task to emulate the characteristic of the process wear pattern, taking into account the required crashing fall. By this measure, the degressive wear curve d, which is at According to the prior art known cutting inserts and shown by the curve 30 in Fig. 11, according to the dash-lined representation considerably shortened in favor of the linear region I. The area of progressive wear is designated by p.

In the upper area of the free surface and as shown in detail in FIGS. 8 and 10, a conically shaped rounded bevel 25 is provided, which has been produced by brush rounding. The rake face 27 (see FIG. 10) is arranged at a rake angle of 0 °. The tapered rounded bevel 25 has a small radius at the first cutting edge end 25a and a large radius at the opposite end 25b. The blade carrier shown in Figs. 6 to 10 is inserted into the milling cutter head such that the end 25a is directed with a small radius toward the tool axis, while the opposite large-radius end 25b is disposed on the tool outer diameter side.

In contrast, FIG. 12 shows a variant embodiment with a double-tapered chamfer in which outer smaller radii 32 for the beveled rounding have been selected in comparison to an inner large radius 33 of the beveled rounding. This results in two% truncated cones, which are set with their bases on top of each other.

With the measure according to the invention a significant reduction of Schneidkantenschartigkeit could be achieved.

Claims

claims

1. cutter support for attachment to a Fräsmesserkopf, consisting of a shaft-shaped pin (11) and a head with soldered cutting edge (12) formed with a rake face and a flank side cutting edge, characterized in that the secondary cutting edge has a rounding (25) whose Radius continuously increases from one minor cutting edge end (25a) at least to the cutting edge center or to the other minor cutting edge end (25b).

2. blade carrier according to claim 1, characterized in that the radius at a cutting edge of a maximum of 6 microns, preferably a maximum of 5 microns different.

3. blade carrier according to claim 1 or 2, characterized in that the width of the rounded edge - viewed perpendicular to the cutting edge profile - at one end (25a) minimized to 0 mm.

4. A blade carrier according to any one of claims 1 to 3, characterized in that on the free surface (28) has a chamfer, which has the rounding that the chamfer at the outer minor cutting edge ends (25 a) have a smaller bevel radiusing than in the middle of Minor cutting edges or as at the other end.

5. blade carrier according to one of claims 1 to 4, characterized in that the width of the chamfer expires at a Nebenschneidkantenende to 0 mm.

6. blade carrier according to one of claims 1 to 5, characterized in that the maximum chamfer width <10 microns, preferably ≤ 4 microns.

7. Schnθidenträger according to any one of claims 5 or 6, characterized in that the chamfer width decreases continuously to 0 mm on both sides.

8. blade carrier according to one of claims 1 to 7, characterized in that the cutting edge or the chamfer (25) is rounded by means of a breast polishing machine, preferably with a camber angle of 89.5 ° to 90 ° to the axis of rotation of the tool carrier is convex ground ,

9. blade carrier according to claim 8, characterized in that the smallest radius of the convex ground free area is at least R = 800 mm.

10. blade carrier according to one of claims 1 to 9, characterized in that the clearance angle is 10 ° ± 2 °.

11. Milling cutter head for orthogonal turning milling with eccentric tool adjustment, in particular for fine milling of bearings of a crank or camshaft with at least two, preferably three eccentrically arranged cutter carriers according to one of the preceding claims, wherein the radius of the Schneidkantenverrundung the cutting edge end, which a smaller circle with rotating Fräsmesserkopf is smaller than the radius of the cutting edge rounding which describes a larger circle of flight.

12. Milling cutter head for orthogonal rotary milling with eccentric tool adjustment, in particular for fine milling of bearings of a crank or camshaft having at least two, preferably three eccentrically arranged cutting carriers with a shaft-shaped pin and a head with soldered cutting edges (12) with one of a rake face (27) and a free surface (28) having a chamfer (25) is formed, wherein the adjacent to the minor cutting edge and on the free surface (28) arranged Bevel (25) has a chamfer width decreasing outwards to O mm, characterized in that the chamfer width increases in each case to the secondary cutting edge center up to a maximum value and that at the minor cutting edge ends the radius of a bevel rounding is minimal and in the secondary cutting edge center maximum.