TOOL FOR METAL CUTTING

Abstract: The present invention relates to a tool for metal cutting, said tool in working position preferably rotating around its longitudinal centre axis, and that the tool comprises a cutting body (10;10a;10b;10c) and a shaft (12;12a;12b;12c), that supports the cutting body (l0;10a;10b;10c). The aim of the invention is to solve the problem to design milling, drilling and turning tools of small dimensions having exchangeable cutting edges. The present invention is characterized inthat the cutting body of the tool is designed as a uniform body comprising integrated cutting edges. By means of a locking screw (11; 11a;11b;11c) the cutting body (10;10a;10b;10c) is detachably fixed in the shaft (12;12a;12b;12c).

Description: This invention relates to a tool for metal cutting, said tool comprising a cutting body and a shaft that supports the cutting body, said cutting body having at least one cutting edge that is integral with the cutting body, said cutting body being detachably connected to a locking screw via hook-shaped means, said hook-shaped means transferring axial forces between the cutting body and the locking screw, said locking screw being provided with an externally threaded portion that is connected to an internally threaded recess provided in said shaft, said locking screw being movable in axial direction by relative rotation of the externally threaded portion and the internally threaded recess, said threaded portions being designed as right hand threads for right hand cutting tools and as left hand threads for left hand cutting tools as defined in the precharacterizing portion of claim 1, see GB-A-990 353. The invention also relates to a cutting body per se according to the precharacterizing portion of claim 5, see GB-A-990 353. It is previously known to use exchangeable cutting edges in the shape of indexable inserts for different types of tools for metal cutting. However, this technique in practice has its limitations due to strength reasons when dealing with milling and drilling tools having a cutting diameter of less than or equal to about 10 mm. From GB-A-990 353 is known a device for securing a tool to a machine tool spindle. Said device transfers axial forces between a tool holder and a locking element. However, said device can only to a limited extent transfer rotational movement between said tool holder and said locking element. This gives rise to problems in respect of handling and securing. The aim of the present invention is to present a design for milling, drilling and turning tools of small dimensions having exchangeable cutting edges, said design avoiding the problems of the known prior art. The aim of the invention is realized by a tool of the type mentioned above that has been given the characteristics of the appending claims. Below embodiments of the invention will be described with reference to the accompanying drawings, where Fig. 1 discloses the elements of a tool according to the invention before they are mounted together; Fig. 2 discloses a tool according to the invention in mounted position; and Fig. 3 discloses in greater detail a side view of a cutting body according to the invention. The embodiment disclosed in Figs 1 and 2 of a tool according to the invention comprises a cutting body 10, a locking screw 11 and a shaft 12. The end 13 of the cutting body 10 that is directed from the shaft 12 is provided with at least one cutting edge that can be given different designs due to the field of application. Thus, the cutting edge or edges are straight and parallel to the longitudinal centre axis of the cutting body when dealing with a shank end mill while the cutting edges are circular when dealing with a radial mill. The enumeration is only exemplifying and the front end of the cutting body 10 is not shown in detail in Figs 1 and 2 since it can be varied in many ways and does not constitute an essential part of the present invention. At the end of the cutting body 10 that is directed towards the shaft 12 a first conical portion 14 is provided that has a first engagment means 15 comprising a first tonque 16 and a first recess 17. In Fig. 3 the cutting body 10 is disclosed more in detail and viewed in the plane of the paper in Figs 1 and 2. From Fig. 3 it can be learnt that the free end 13 of the cutting body 10 is provided with a key handle 32. The use of said key handle 32 is explained below. The locking screw 11 has a second conical portion at the end that is directed towards the cutting body, said second conical portion having a second engagement means 19 that is intended to cooperate with the first engagement means 15. As is obvious from Figs 1 and 2 the arrangement of the second engagement means 19 has caused an essential portion of the second conical portion 18 to be deleted. The second engagement means 19 comprises a second tongue 20 and a second recess 21. In working condition the first tongue 16 cooperates with the second recess 21 and the second tongue 20 with the first recess 17. Inside of the second engagment means 18, in axial direction, the locking screw 11 has an externally threaded, preferably cylindrical portion 22. An Allen key insert 23 is arranged at the innermost end of the locking screw 11 thus making it possible to loosen and tighten the locking screw 11 through the internal duct 24 of the shaft 12. However, normally the tightening and loosening of the locking screw 11 is carried out via the external key handle 32. The shaft 12 is provided with a conical seat 25 at the end that is directed towards the cutting body 10. Said conical seat 25 receives the first and second conical portions 14 and 18 of the cutting body 10 and the locking screw 11, respectively. Inside of the conical seat 25 the shaft 12 has a substantially cylindrical, internally threaded portion 26 that cooperates with the externally threaded portion 22 on the locking screw 11. Inside of the portion 26 the duct 24 mentioned above is located. In Fig. 1 the starting position for mounting of the cutting body 10 in the shaft 12 is disclosed. In this position the locking screw 11 is displaced axially towards the open end of the conical seat 25. Thereby it is possible that the first engagement means 15 of the cutting body 10 is inserted into the conical seat 25 and automatically takes a position for engagement with the second engagment means of the locking screw 11. When rotating the cutting body 10 in the direction of the arrow 27, preferably by a wrench that is engaging the key handle 32, the locking screw 11 will also rotate in the direction of the arrow 27. Cooperation between the external thread 22 and the internal thread 26 causes the locking screw 11 and also the cutting body 10 to be displaced axially into the shaft 12 until the conical portion 14 contacts the conical seat 25, i.e. the position according to Fig. 2 has been achieved. The cutting body 10 is now in a satisfying way anchored in the shaft 12. In this connection it should be pointed out that the thread 22 of the locking screw 11 has two purposes, namely first to place the cutting body 10 in a fixed position in the shaft in the mounting state, and second, during use of the cutting tool, always to guarantee that the cutting body 10 remains in its fixed position regardless of how the dimensions of the cutting body 10 and the shaft 12 are affected by heat generated from the machining. The threads 22 and 26 are designed as right hand threads for right hand cutting tools and as left hand threads for left hand cutting tools. When the cutting body 10 is to be exchanged one acts in the opposite way compared to the mounting, i.e. rotation of the cutting body 10 in opposited direction to the arrow 27 is carried out until the position of Fig. 1 is achieved. At that position the cutting body 10 can be removed from the shaft 12. In the embodiment described above the cone angle for the cutting body and the seat should be less than 25°. It is also pointed out that the embodiment described above refer to a mill, i.e. a tool that rotates relative to its longitudinal centre axis. Mills having small cutting tips are probably the dominating application field for the present invention but also drilling and turning tools are within the scope of the invention. The invention is in no way restricted to the embodiment described above but can be freely varied within the scope of the appending claims.

Claims: Tool for metal cutting, said tool comprising a cutting body (10) and a shaft (12) that supports the cutting body (10), said cutting body (10) having at least one cutting edge that is integral with the cutting body (10), said cutting body (10) being detachably connected to a locking screw (11) via hook-shaped means (15,19), said hook-shaped means transferring axial forces between the cutting body (10) and the locking screw (11), said locking screw (11) being provided with an externally threaded portion (22) that is connected, to an internally threaded recess (26) provided in said shaft (12), said locking screw (11) being movable in axial direction by relative rotation of the externally threaded portion (22) and the internally threaded recess (26), said threaded portions (22,26) being designed as right hand threads for right hand cutting tools and as left hand threads for left hand cutting tools, characterized in that the shaft (12) is provided with a conical seat (25), that the cutting body (10) is insertable in or removable from the conical seat (25) when the locking screw (11) is displaced from its innermost position to an intermediate position, that the hook-shaped means (15,19) includes tongues (16,20) and recesses (17,21) of the cutting body (10) and locking screw (11), resp, said tongues (16,20) and recesses (17,21) cooperating to permanently transfer rotational movement, in" either direction of rotation, between the cutting body (10) and the locking screw (11) when the locking screw (11) is in a position between the intermediate position and the innermost position, that the cutting body (10) is provided with a circumferential conical portion (14) that is received in the conical seat (25) of the shaft in working position of the tool, and that the tongue (16) and the recess (17) of the cutting body (10) are located inwardly of an imaginary extension of the outer periphery of the conical portion (14). Tool according to claim 2, characterized in that the hook-shaped means is designed as a dove-tail connection. Tool according to any one of the previous claims, characterized in that the cutting body (10) between the cutting edge and the conical portion (14) is provided with a key handle (32). Tool according to any one of the previous claims, characterized in that the shaft (12) is provided with an internal duct (24) in order to give access to a hand implement when disconnecting the cutting body (10) from the locking screw (11). Cutting body (10) to be used in a tool for metal cutting according to any one of claims 1-4, said cutting body (10) having at least one cutting edge that is integral with the cutting body (10), said cutting body (10) at its end remote from the cutting edge being provided with hook-shaped means (15), including a tongue (16) and a recess (17), said recess (17) being located between the tongue (16) and the cutting edge, characterized in that the hook-shaped means (15) is provided in a conical portion (14) of the cutting body (10), that said tongue (16) and said recess (17) are located inwardly of an imaginary extension of the outer periphery of the conical portion (14), and that said tongue (16) and said recess (17) are facing directly towards said imaginary extension of the outer periphery of the conical portion (14). Cutting body according to claim 5, characterized in that the hook-shaped means is designed as one part of a dove-tail connection. Cutting body according to any one of claims 5 or 6, characterized in that a key handle (32) is provided between the cutting edge and the conical portion (14).

Inventors: EKLUND, SVEN, STRAND, BENGT
Applicants: SECO TOOLS AB
Application year: 1988
Main classification: B23B51
IPC codes: B23B31, B23C5