WO2009147461A1

WO2009147461A1 - Milling tool

Info

Publication number: WO2009147461A1
Application number: PCT/HU2009/000049
Authority: WO
Inventors: László VILMÁNYI
Original assignee: VILMÁNYI, Gábor
Priority date: 2008-06-06
Filing date: 2009-06-04
Publication date: 2009-12-10
Also published as: JP3172438U; KR20110003520U; FIU20100551U0; AT12539U1; CZ22318U1; FI9221U1; DE212009000076U1; SK5894Y1; AT12539U8; RO201000069U2; RO201000069U8; SK50782010U1; RO201000069U3

Abstract

The object of the invention is a milling tool having a tool body, a shank portion, and cutting edges adapted for machining a workpiece, the cutting edges being disposed on the tool body. Corner edges (3) of the tool, formed at the junction of peripheral (1) and front (2) edges, are arranged such that the corner edges of adjacent cutting edges have different geometrical arrangements.

Description

Milling tool

Technical field

The object of the invention is a milling tool having a tool body, a shank portion, and cutting edges adapted for machining a workpiece, where the cutting edges are disposed on the tool body.

Background art

Milling tools are devices generally applied in machining technology for removing stock from workpieces.

Fig. 1 illustrates the operation of a conventional shank-type milling tool. The tool revolves around its own axis with an angular velocity ω and also advances with an instantaneous velocity v relative to the workpiece. The milling tool S has cutting edges arranged either parallel with the axis of symmetry of the tool S or along a helical line coaxial with the axis of symmetry. These cutting edges are the peripheral edges 1 of the tool S. The pitch angle (the angle between the tangent of the edge line and the principal axis of the tool) of a helically arranged edge may be: a./ constant (constant-pitch helix) b./ variable (variable-pitch helix).

Variants a./ and b./ may also be combined in different ways in actual implementations. For instance in case of a tool with 6 edges edge pairs consisting of facing edges numbered 1 and 4, 2 and 5, 3 and 6 respectively have constant pitch angles of 60°, 55°, and 65°. According to another possible implementation with 6 edges, facing edges 1 and 4 have a constant pitch angle of 60°, whereas edges 2 and 5 have a variable pitch angle linearly decreasing from 65° to 55°. Cutting edges disposed on the front surface of the tool are the front edges 2 of the tool. Corner edges of the tool S are formed at the intersection of peripheral edges 1 and front edges 2. Conventional corner edge arrangements are illustrated in Figs 3a-3d. These typical corner edge arrangements are the following: a./ sharp corner edge b./ singly bevelled corner edge c.l multiply bevelled corner edge

6.1 radiused corner edge. A common characteristics of conventional corner edge arrangements is that all corner edges 3 of the tool S have identical geometrical arrangement (a./, b./, c.l, d.).

Operating parameters - such as cutting depth, cutting speed, feed rate - as well as the service life of the tool are greatly influenced by the geometrical arrangement of the corner edges.

In case the tool S has no chip-breaking grooves 4 on its cutting edges each cutting edge removes a chip element having a width B and thickness H, as it is illustrated in Fig. 4a.

Conventional milling tools S often comprise so-called chip-breaking grooves 4. Chip-breaking grooves are produced by forming multiple grooves

4 having a width d on cutting edges of the tool such that there is an axial distance L between grooves and grooves disposed on adjacent edges are shifted in an axial direction relative to each other by a distance L/2. Thereby, as it is illustrated in Fig. 4b, chip elements removed by individual edges will have a maximum width L-d, which is advantageous as far as usability and tool workload are concerned.

Disclosure of Invention

The objective of the present invention is to provide a milling tool that has longer service life and better usability (under the same operational conditions) than conventionally arranged milling tools, and/or is capable of machining operations conforming to higher technological requirements.

The present invention is based on the recognition that the configuration of the corner edge of the tool critically affects service life and other technological parameters.

The milling tool according to the invention has a tool body, a shank portion and cutting edges adapted for machining a workpiece, the cutting edges being disposed on the tool body or on insert plates attached to the tool body, and is characterised by that corner edges of the tool-, formed at the junction of peripheral and front edges, are arranged such that the corner edges of adjacent cutting edges have different geometrical arrangements.

A preferred embodiment of the milling tool according to the invention has a shank-type or disc-type configuration.

Another preferred embodiment of the milling tool according to the invention has cutting insert plates, where the corner edge of each insert plate is formed by adjoining sections of different geometrical arrangement.

A further preferred embodiment of the milling tool according to the invention has such a geometrical arrangement where the tool has an even number (2, 4 2n) of edges, with the odd edges (1 , 3, 2n-1 ) having a radiused configuration and the even edges (2, 4, ..., 2n) having a bevelled configuration.

Brief description of drawings

A known-art milling tool implementation as well as preferred embodiments of the milling tool according to the invention are explained in detail with reference to the attached drawings where

Fig. 1 shows a conventional, known-art shank-type milling tool in operational position,

Fig. 2 shows the edges of a known-art milling tool, Fig. 3a-3d illustrate known corner edge configurations, Fig. 4a shows the side view of a known milling tool without chip breaking grooves,

Fig. 4b shows the side view of a known milling tool comprising chip breaking grooves, Fig. 5 shows the schematic view of the tool according to the invention,

Fig. 6 illustrates an embodiment of the milling tool according to the invention adapted for producing a bevelled corner,

Fig. 7 illustrates an embodiment of the milling tool according to the invention adapted for producing a curved corner, Fig. 8 illustrates the geometry of the stock removal process of the milling tool of Fig. 6, and

Fig. 9 shows the geometry of the stock removal process of the milling tool of Fig. 7.

Best mode of carrying out the invention

Figs. 1 -4 illustrate the geometrical arrangement of various known-art milling tools presented in detail above in the section describing the prior art for the milling tool according to the present invention.

Fig. 5 is the schematic view of the shank-type milling tool according to the invention, illustrating the configuration of the peripheral edges 1 , front edges 2, corner edges 3, and the chip removal groove 7.

The area of the tool S receiving the highest stress is the corner edge 3.

Fig. 6 shows the geometry of a corner edge 3 machining a bevelled- edge corner, where the front edge 3 consists of a first edge portion, of legs 9, 10 of a right-angled triangle, and an adjoining curved edge portion having a radius R.

Thereby the corner is substantially formed in a single step. Fig. 7 illustrates another embodiment of the milling tool according to the invention, applicable for machining rounded comer portions. Here the first portion of the front edge 3 of the tool consists of a hypotenuse 1 1 portion connecting the legs 12, 13 of a right-angled triangle having an angle α, and an adjoining curved portion having a radius R.

The essential feature of the invention is that chip breaking is achieved at corner edges 3 of the tool S by configuring adjacent corner edges 3 such that they have different geometrical arrangements.

Fig. 8 shows chip cross section shapes of chips cut by the milling tool having different corner edge 3 geometries on adjacent cutting edges as illustrated in Fig. 6. Cross sections are shown as a function of chip thickness H in drawings 1 -4 as the cutting edge having a bevelled corner edge geometry proceeds on a surface portion machined by a cutting edge having a radiused corner edge geometry.

Fig. 9 shows chip cross section shapes of chips cut by the milling tool having different corner edge 3 geometries on adjacent cutting edges as illustrated in Fig. 7. Cross sections are shown as a function of chip thickness H in drawings 1 -4 as the cutting edge having a radiused corner edge geometry proceeds on a surface portion machined by a cutting edge having a bevelled corner edge geometry.

Corner edges 3 of the milling tool according to the invention may have geometrical arrangements different from the geometry described above, provided that adjacent cutting edges have different - such as radiused or multiply bevelled corner edge geometries Bevelled portions may have shapes described by parabolic or any other functions.

Also, by applying corner edges with other geometrical arrangements, single-step plane milling may be performed to provide a good-quality machined surface that does not require finishing. List of references

S tool

M workpiece

V instantaneous velocity ω angular velocity

1 peripheral edge

2 front edge

3 corner edge

4 groove

5 shank portion

6 peripheral surface

7 groove

8 leg

9 leg

10 leg

1 1 hypotenuse

12 leg

13 leg

14 chip width

H chip thickness d groove width

L axial groove distance α bevel angle

Claims

1 . Milling tool having a tool body, a shank portion (5) and cutting edges (1 , 2, 3) adapted for machining a workpiece (M), the cutting edges (1 , 2, 3) being disposed on the tool body or on insert plates attached to the tool body, characterised by that corner edges (3) of the tool (S), formed at the junction of peripheral (1 ) and front (2) edges, are arranged such that the corner edges (3) of adjacent cutting edges have different geometrical arrangements.

2. The milling tool according to Claim 1 , characterised by that it has a shank-type or disc-type configuration.

3. The milling tool according to Claims 1 or 2, characterised by that it has cutting insert plates, where the corner edge of each insert plate is formed by adjoining sections of different geometrical arrangement.

4. The milling tool according to any one of Claims 1 -3, characterised by that it has such a geometrical arrangement where the tool has an even number (2, 4, ..., 2n) of edges, with the odd edges (1 , 3, 2n-1 ) having a radiused configuration and the even edges (2, 4, ..., 2n) having a bevelled configuration.

5. The milling tool according to any one of Claims 1-3, characterised by that the tool (S) has such a geometrical arrangement where edge radiuses R are between 0.5-5 mm and edge bevel angles α are between 15-75°.