EP2081718A1

EP2081718A1 - Finishing/roughing mill

Info

Publication number: EP2081718A1
Application number: EP07817605A
Authority: EP
Inventors: Zdenek Vratny; Georg Finger
Original assignee: Hofmann & Vratny oHG
Current assignee: Hofmann & Vratny oHG
Priority date: 2006-10-28
Filing date: 2007-10-01
Publication date: 2009-07-29
Also published as: WO2008052503A1; DE202006016531U1

Abstract

The finishing/roughing mill (1) has a cylindrical tool shank (2) and a milling region (3), which adjoins said shank and has a number of milling faces (4), which are located in the circumferential direction of the mill and extend in a helix with a lead angle set with respect to the centre axis of the mill in the direction of the tool shank. Each milling face (4) has alternating roughing regions (11) and finishing regions (12), each finishing region of a milling face lying at essentially the same axial height as a roughing region of an adjacent milling face in the axial direction of the mill. In the axial direction of the mill (1), the finishing region (12) of a milling face (4) preferably covers or overlaps the roughing region (11) of the milling face (4) that is adjacent in the circumferential direction of the mill (1).

Description

Finishing / Roughing

The invention relates to a finishing / roughing cutter according to the preamble of claim 1.

Such cutters usually have a cylindrical tool shank which can be clamped at one, its upper end, into a milling machine. At this tool shank is followed by a milling area, which has a plurality of milling surfaces located in the Urαfangsrichtung of the cutter, each with a milling edge. Each milling surface extends in a helix with an inclined angle with respect to the central axis of the milling cutter toward the other, lower end of the milling cutter and ends there on the face of the milling cutter in a cutting edge located in a plane perpendicular to the central axis of the milling cutter ,

In a roughing cutter, the milling surfaces are designed as roughing surfaces with a roughened surface or with a serrated edge, which is usually referred to as toothing. With such roughing cutters, workpieces can first be rough cut.

In a finishing mill milling surfaces usually have no teeth but are smooth; These finishing cutters are used for smoothing the surfaces of a workpiece which are pre-milled, for example by a roughing cutter.

Finishing / roughing cutters combine the function of a roughing cutter and a finishing cutter. In each case, these milling cutters have a milling surface formed and serve as Simple milling surface, wherein the adjacent milling surface is formed as a roughing milling surface with a toothing.

Cutters are usually made from a pressed metal powder which is subsequently sintered. The cutter is therefore very hard, but also very brittle at the same time. At high loads, which are exerted on the cutter, this gets into vibration by these loads, which can definitely lead to the breakage of the milling cutter. Thus, it is necessary to achieve a smooth running of the milling cutter when machining workpieces.

In the conventional finishing / roughing cutters, although the roughing surfaces, which are heavily loaded, significantly reduce the stresses exerted on the milling cutter, high stresses can then again occur at the finishing milling surfaces, so that the milling cutter can in turn vibrate and break.

In addition, it is desirable to achieve in such milling as short as possible from the workpiece milled chips, which can then be removed well. Longer shavings can only be dissipated poorly, in some cases resulting in so-called chip clamps, through which, if necessary, the machining process must be interrupted.

In addition, finishing / roughing cutters can only be operated at relatively low feed rates when machining workpieces due to the above-mentioned problems.

The invention has for its object to provide a sizing / roughing, with a virtually vibration-free quiet running can be achieved. Furthermore, the loads of the milling cutter should be reduced in particular by the configuration of the helically extending milling surfaces.

Furthermore, only relatively short chips are to be generated with the cutter, which can be easily dissipated.

Finally, it is an object of the invention to increase the feed rate of a finishing / roughing mill over known milling cutters.

These objects are achieved according to the invention by the features of claim 1.

Accordingly, each helical milling surface alternately roughing and sizing areas, which follow each other in the axial direction of the cutter at relatively short intervals. Each finishing area of a milling surface in the axial direction of the milling cutter lies substantially at the same axial height of a roughing area of an adjacent milling area and preferably covers the roughing area of the adjacent milling area or even slightly overlaps the roughing area of the adjacent milling area on both sides.

It has been found that such a configuration of the milling surfaces, the loads on the cutter when milling a workpiece are significantly reduced, so that the cutter is virtually no longer vibrated and running smoothly. This is essentially attributed to the alternating arrangement of finishing and roughing areas along each milling surface. It has been shown that a finishing / roughing mill according to the invention oscillates significantly less than a conventional cutter, in each case a milling surface as a finishing milling surface and the adjacent milling surface is designed as a roughing-milling surface. For this reason, fractures of the milling cutter or damage to the milling surfaces or their cutting are practically prevented.

In addition, due to the overlapping or overlapping of the roughing area of an adjacent milling surface in the axial direction through the finishing area of the adjacent trailing milling surface, a reworking of the workpiece, for example a smoothing of the surface, is no longer necessary in many cases.

A further improvement in the stability of the milling cutter can be achieved if it is unevenly divided. An uneven pitch of the milling cutter means that the cutting edges on the face of the milling cutter are not arranged at regular angular intervals. In addition, the pitch angle of adjacent milling surfaces have different pitch angles. By such a design, the forces are better distributed to the cutter, so that a swinging of the cutter prevented and a smooth running is ensured.

For example, in a sizing / roughing mill with four helical milling surfaces, two opposite milling surfaces have a pitch of 30 ° with respect to the center axis of the cutter, while the other two milling surfaces have a dynamic pitch angle that is about 30 ° in the area of the face of the cutter and continuously increases toward the tool shank up to, for example, 35 °. The cutting edges in the end face of the milling cutter lie radially in pairs opposite each other, wherein the cutting edges of the milling surfaces are offset by a few degrees, for example 5 °, with the dynamic pitch angle in the circumferential direction in relation to the cutting edges of the milling surface with a constant pitch angle. The distance between the cutting edges of the With this configuration, milling surfaces become increasingly narrow in the direction of the clamping end of the milling cutter, so that shorter chips are also produced here.

Cutters with unequal pitch are known per se, but this uneven pitch in conjunction with the configuration of the milling surfaces with alternating finishing and roughing areas gives an additional advantageous effect in that practically the cutter no longer vibrates, so that a particularly smooth running is generated.

It goes without saying that the given numerical values for the uneven pitch are exemplary and can be modified depending on the material of the workpiece to be machined. In addition, such uneven pitch roughing / roughing cutters may be milling cutters having two, four, six, eight, etc. milling surfaces.

With a finishing / roughing cutter according to the invention, the machining time of a workpiece can be reduced by up to 30% compared to conventional milling cutters, the workpiece, as already mentioned, having a smooth surface, which frequently does not have to be reworked.

The invention is explained in more detail in an embodiment with reference to the drawing. In this represent:

Figure 1 is a view of a finishing / roughing cutter with four helically extending milling surfaces according to the invention;

FIG. 2 shows a detail view of alternating roughing and finishing areas along a milling surface in the milling cutter according to FIG. 1; FIG. 3 shows a development of the four milling surfaces of the milling cutter according to FIG. 1; and

Figure 4 is a plan view of the end face of the cutter with the located in this cutting.

A finishing / roughening cutter 1 has, according to FIG. 1, a cylindrical tool shank 2, which is clamped with its upper end in FIG. 1 into a milling machine (not shown here). The adjoining the smooth cylindrical tool shank 2 region of the milling cutter 1 is provided as a milling section 3 with four angularly along the circumference of the milling cutter offset milling surfaces 4, which are located in the periphery of the milling cutter and band-shaped from a clamping end of the tool shank 2 opposite End face 5 each extend in a screw gear in the direction of the upper end of the milling area. The milling surfaces each have a milling edge 6. Between adjacent milling surfaces 4, respectively, hollow chip removal grooves 7 are located, via which the chip groove arising during milling is removed.

The milling surfaces 4 terminate in the end face 5 of the milling cutter in each case in a cutting edge; Here, from the center of the front side radially opposite cutting two milling surfaces with 8-1 and 8-2 respectively; see. figure

As can be seen from FIG. 1, each milling surface 4 alternately has short roughing regions 11 and sizing regions 12 in the axial longitudinal direction of the milling cutter 1. The roughing regions 11, as shown in Figure 2, each have a serrated edge, whereas the sizing regions 12 have a lying in the periphery of the milling cutter smooth surface. The roughing regions 11 cover in the axial direction of the milling cutter, for example, a length of 5 mm, the sizing regions 12 a range of for example 6 mm. These numerical values are merely exemplary.

As can be seen from the partial representation of a development of the milling area 3, the trailing sizing area 12, seen in the axial direction of the milling cutter, cover the roughing areas 11 of a circumferentially adjacent leading milling surface 4, or overlap on both sides, as this by the dotted lines 13 and 14 is shown in FIG.

In addition, the mill 1, as known per se, an uneven pitch, that is, that the cutting edges 8-1 of two radially opposite milling surfaces 8-1 and 8-2 in the circumferential direction of the milling cutter 1 have an angle different from 90 ° , In this case, the angle between the cutting edge 8-1 and the cutting edge 8-2 is 95 °, the angle between this second cutting edge 8-2 and the subsequent cutting edge 8-1 is 85 ° and so on.

In addition, the milling surfaces 4 with the cutting edges 8-1 relative to the central axis of the milling cutter 1 a pitch angle of 30 ° in this case, the milling surfaces with their cutting 8-2 a different pitch angle, which is 30 ° in the region of the front page continuously increased in this case 35 °, as this is exaggerated in Figure 3 is shown. It should be noted that the numerical values given are merely exemplary; Among other things, they depend on the material of the workpiece to be machined.

Claims

protection claims

1. sizing / Schruppfräser (1) with a cylindrical tool shank (2) which is clamped at one, upper end in a milling machine, and with a subsequent to the tool shank milling area (3), which has a plurality of circumferentially of the milling cutter milling surfaces (4), each having a milling edge (6), wherein each milling surface extends in a helical gear with an employee compared to the central axis of the cutter pitch angle towards the other, lower end of the cutter and there on the front side (5) of the cutter in a cutting edge (8-1, 8-2) which is located in a plane perpendicular to the central axis of the milling cutter, wherein the milling surfaces are formed as roughened surfaces (11) with a roughened surface and as smooth surface finishing surfaces (12) characterized in that each milling surface (4) alternately roughing areas

(11) and sizing regions (12), and that each sizing region of a milling surface in the axial direction of the milling cutter lies on a substantially same axial height of a roughing region of an adjacent milled surface.

2. Milling cutter according to claim 1, characterized in that the finishing area (12) of a milling surface (4) in the axial direction of the milling cutter (1) the roughing area (11) in the circumferential direction of the milling cutter (1) adjacent milling surface

(4) covered.

3. Milling cutter according to claim 2, characterized in that the sizing region (12) of a milling surface (4) in the axial direction of the milling cutter (1) overlaps the roughing region (11) of the adjacent milling surface on both sides.

4. Milling cutter according to one of the preceding claims, characterized in that the cutter (1) is divided equally, wherein the cutting edges (8-1, 8-2) in the circumferential direction of the milling cutter (1) adjacent milling surfaces (4) in the end face ( 5) of the milling cutter are arranged at regular constant angular intervals.

5. Milling cutter according to one of claims 1 to 3, characterized in that the cutter (1) is divided unequally, wherein the cutting edges (8.1, 8-2) in the circumferential direction of the milling cutter adjacent milling surfaces (4) in the end face (5) Milling cutter are arranged at irregular angular intervals.

6. Milling cutter according to one of the preceding claims, characterized in that the pitch angle of at least one milling surface (4) varies over the axial length of the milling area.

7. Milling cutter according to claim 6, characterized in that the changing pitch angle of the at least one milling surface (4) starting from the end face (5) of the milling cutter (1) increases continuously.

8. cutter according to claim 6 or 7, characterized in that in the circumferential direction of the milling cutter (1) alternately milling surfaces (4) with a constant pitch angle and milling surfaces (4) with changing pitch angle are arranged.

9. Milling cutter according to one of the preceding claims, characterized in that the cutter (1) paired milling surfaces

(4), which, as well as their cutting edges (8-1, 8-2) in the front side of the cutter, in the circumferential direction of the cutter at an angle of 180 ° opposite.

10. Milling ^' he according to one of the preceding claims, characterized in that the cutter (1) in the circumferential direction has four milling surfaces (4).