HK1023741B

HK1023741B - Tool for chip-removal

Info

Publication number: HK1023741B
Application number: HK00102989.9A
Authority: HK
Inventors: 本特‧斯特兰德; 卡尔-埃里克‧贝里勒夫
Original assignee: 塞科机床公司
Priority date: 1996-12-03
Filing date: 1997-10-31
Publication date: 2003-03-14

Description

Chip removal cutter

The present invention relates to a tool for rotary chip removing machining and to a cutting head for a tool.

The US patent application US-A-4,850,759 has long been known as A solution to the problem of small-sized milling cutters and drilling tools with replaceable cutting edges. However, in some high speed rotation conditions, known tools tend to vibrate on the workpiece, creating unwanted pattern or chatter marks. These, along with the knives sometimes becoming too hot, present problems to the user.

It is an object of the present invention to provide a tool that maintains rigidity even at high rotational speeds.

Another object of the present invention is to provide a tool with better cooling effect.

It is a further object of the present invention to provide a cutting head having improved stability and improved cooling.

These and other objects of the present invention are achieved by the above described tool and cutting head. According to one aspect of the invention, there is provided a tool for rotary chip removing machining, the tool comprising: cutting head, a retention means and a tool shank, wherein the cutting head is provided with at least one cutting edge which is integrally formed with the cutting head, said cutting head and retention means comprising overlapping first and second asymmetric means of different materials for mounting the cutting head to the tool shank, the first asymmetric means of the cutting head comprising a central recessed portion of reduced mass, and the tool comprising an axial channel extending through at least the first asymmetric means for conveying flushing medium on the one hand and for reducing the mass of the first asymmetric means on the other hand.

According to another aspect of the present invention there is provided a cutting head with at least one cutting edge for mounting on a tool for rotary chip removing machining, the tool comprising: cutting head, a retention means and a tool shank, wherein the cutting head is provided with at least one cutting edge which is integrally formed with the cutting head, said cutting head and said retention means comprising mutually overlapping asymmetric means of different materials for mounting the cutting head to the tool shank, the first asymmetric means of the cutting head comprising a mass-reducing recess portion which extends through the first asymmetric means for, on the one hand, conveying flushing medium and, on the other hand, reducing the mass of the first asymmetric means.

Embodiments of the invention are described below with reference to the accompanying drawings, in which:

FIG. 1 is a partial cross-sectional view of the present tool in an assembled state;

fig. 2A and 2B are side views showing the cutting head of the present invention in greater detail;

FIG. 3 shows a bottom view of the cutting head of the present invention;

fig. 4 is a top view of the cutting head of the present invention;

fig. 5 is a cross-sectional view taken along line V-V in fig. 2A.

The embodiment of the tool of the present invention shown in fig. 1 comprises a cutting head 10, a locking screw 11 and a shank 12. The tool comprises an axial channel extending beyond the hook means 15, 19 on the cutting head and the locking screw, respectively. The channel passes through the hook means 15 of the cutting head but preferably not through the hook means 19 of the locking screw. The function of this channel is on the one hand to convey the flushing medium and on the other hand to reduce the mass of the device. The channel penetrates the edge surface of the hook means 15 of the cutting head, and in the area of the hook means the channel occupies a larger space in the cutting head than in the locking screw. In this way the centre of gravity of the hook-shaped device region is arranged closer to the rotational axis CL of the tool, so that the tool is dynamically centered. The asymmetric device 15 made of the material of the highest specific gravity comprises a mass-reducing recess 34.

The cutting head 10 is arranged with at least one cutting edge on the end 13 facing away from the shank 12, which cutting edge is given a different design depending on the range of use. Fig. 2A-5 show in detail a preferred front end shape of the cutting head 10. The cutting head 10 is made of a hard material, preferably cemented carbide, and comprises three helical first or major cutting edges 27. The number of main cutting edges may alternatively be one, two or four to six. Each major cutting edge 27 is formed along the intersection of a clearance surface or projecting edge land 28 and a chip surface or chip flute 29. The main cutting edges 27 lie on a common, imaginary cylinder whose axis coincides with the cutting-head axis of rotation CL of the tool. Each chip flute 29 is concavely formed, and each chip flute 29 extends in an axially inward direction from a adjoining second or secondary cutting edge 30 to the beveled or free end 13 of the cutting head. The secondary cutting edges 30, which are formed at the intersection of the chip flutes 29 and the end surfaces 31 and extend substantially radially inwardly from the imaginary cylinder, are connected substantially to the axis of rotation CL of the cutting head, so that the tool can drill down into the workpiece during milling. Each pair of main and auxiliary cutting edges is fed with flushing medium through the hole 33. The three holes 33 are suitably symmetrically arranged about the axis of rotation of the cutting head. The bores are connected to a central channel 34, and the central channel 34 terminates in the surface of the other free end of the cutting head.

The cutting head is provided with a first conical portion 14 at the end facing the tool shank 12, which conical portion 14 is provided with first coupling means 15, which first coupling means 15 in the embodiment shown comprises a first male portion 16 and a first female portion 17. The cutting head 10 is provided with a wedge-shaped clamping means 32 in the middle, the use of which is explained below.

The locking screw 11 is preferably made of steel, which locking screw 11 has a second conical portion 18 at the end facing the cutting head, which second conical portion 18 is provided with second coupling means 19, which second coupling means 19 are intended to cooperate with the first coupling means 15. The configuration of the second connecting means 19 means that a substantial part of the second conical portion 18 has been removed, as shown in fig. 1. The second connecting means 19 comprise a second male portion 20 and a second female portion 21. In the operating state, the first projecting portion 16 cooperates with the second recessed portion 21, while the second projecting portion 20 cooperates with the first recessed portion 17. The second projection 20 is preferably intact, i.e. there is no recess in this projection through which the flushing medium flows, so that the mass of the second connecting means 19 is relatively the same as the mass of the first connecting means 15, so that wobbling is substantially prevented.

The locking screw 11, which is axially located in the second connecting means 19, has an externally threaded, preferably cylindrical, part 22 in the axial direction. A hexagonal wedge-shaped clamping device 23 is arranged at the axially innermost end of the locking screw 11, so that it is possible to effect loosening or tightening of the locking screw 11 via an internal channel 24 of the shank 12. In general, however, the loosening or tightening of the locking screw 11 is effected by means of an external wedge-shaped clamping device 32. Alternatively, the thread 26 may be provided on one end of the releasable sleeve, which is then provided with an external thread and a wedge-shaped clamping means on the other end.

On the end of the shank 12 facing the cutting head 10, a conical seat 25 is arranged, which conical seat 25 is intended to receive the respective first conical portion 14 and second conical portion 18 of the cutting head 10 and the locking screw 11. The shank 12 has, inside the conical seat 25, a substantially cylindrical, internally threaded portion 26, which portion 26 cooperates with the externally threaded portion 22 of the locking screw 11. This portion 26 is located axially outside the above-mentioned channel 24.

The US patent application US-A-4,850,789 describes the mounting and dismounting of the tool in more detail and is hereby incorporated into the present description. The mating relationship between the external and internal threads 22, 26 causes the lock screw 11 and the cutting head 10 to move axially into the shank 12 until the tapered portion 14 abuts the tapered seat 25, i.e., the position of fig. 1 is reached. The cutting head 10 is now secured in the tool shank 12 in a satisfactory manner. Thus, a flushing medium flow channel through the tool is formed by the recesses 24, 24A, 34 and 33.

Threads 22 and 26 are formed as right-hand threads on a right-hand cutting tool and threads 22 and 26 are formed as left-hand threads on a left-hand cutting tool.

For the above embodiments, the taper angle of the cutting head and the seat should be less than 25 °. Furthermore, it should be noted that the described embodiments relate to milling cutters, i.e. tools that rotate about their longitudinal central axis. A milling cutter with a small cutting portion should be the first aspect of the application of the invention, but a drilling tool also falls within the scope of the invention.

The invention is in no way limited to the above-described embodiments and many variations are possible within the scope defined in the following claims.

Claims

1. A tool for rotary chip removing machining, the tool comprising: cutting head (10), a retention means (11) and a tool shank (12), wherein the cutting head (10) is provided with at least one cutting edge (27, 30) which is integrally formed with the cutting head, said cutting head and retention means comprising overlapping first (15) and second (19) asymmetric means of different materials for mounting the cutting head to the tool shank, characterized in that: the first asymmetric means (15) of the cutting head (10) comprises a central recessed portion (34) of reduced mass, and the tool comprises an axial channel (24, 24A, 33, 34) extending at least through the first asymmetric means (15) for conveying flushing medium on the one hand and for reducing the mass of the first asymmetric means (15) on the other hand.

2. The tool according to claim 1, wherein: the overlapping asymmetrical means consist of hook-shaped means (15, 19), the cutting head being made of cemented carbide and the second asymmetrical means (19) being made of steel.

3. The tool according to claim 1 or 2, wherein: the retention means (11) has an externally threaded portion (22) and is intended to cooperate with an internally threaded recess (26) in the shank (12) in the operative condition of the tool, a conical portion (14) being provided on the cutting head (10), the shank (12) being provided with a conical seat (25), the conical seat (25) receiving the conical portion (14) in the operative condition of the tool, the cutting head (10) being releasably coupled to the retention means (11) by hook means (15, 19).

4. The tool according to claim 3, wherein: the channels penetrate the edge surfaces of the hook means (15) of the cutting head (10).

5. A cutting head with at least one cutting edge (27, 30) for mounting on a tool for rotary chip removing machining, the tool comprising: cutting head (10), a retention means (11) and a tool shank (12), wherein the cutting head (10) is provided with at least one cutting edge (27, 30) which is integrally formed with the cutting head, said cutting head and said retention means comprising overlapping asymmetric means (15, 19) of different materials for mounting the cutting head to the tool shank, characterized in that: the first asymmetric means (15) of the cutting head (10) comprises a mass-reducing recessed portion (34), which recessed portion (34) extends through the first asymmetric means (15) for conveying flushing medium on the one hand and for reducing the mass of the first asymmetric means (15) on the other hand.

6. The cutting head according to claim 5, wherein: the first asymmetric means consists of hook means (15) and the cutting head is made of cemented carbide.

7. The cutting head according to claim 6, wherein: the central recessed portion (34) penetrates the edge surface of the hook-shaped means (15) of the cutting head.

8. The cutting head according to claim 7, wherein: the cutting head (10) comprises one to six helical main cutting edges (27), each of said main cutting edges (27) being formed along the intersection of a clearing surface (28) and a chip-receiving surface (29), the main cutting edges (27) being arranged on a common, imaginary cylinder, the axis of which coincides with the axis of rotation CL of the cutting head.

9. The cutting head according to claim 8, wherein: each primary cutting edge (27) is connected to a secondary cutting edge (30), each pair of primary and secondary cutting edges being supplied with flushing medium through holes (33), said holes (33) being symmetrically arranged around the axis of rotation CL of the cutting head, the holes leading to a central recessed portion (34) terminating in a surface at the other free end of the cutting head (10).