TOOL AND COUNTERSINKER FOR CHIP REMOVING MACHINING

Abstract: The present invention relates to a tool for chip removing machining, said tool comprising a drill (1) and a countersinker (3) mounted thereto, which has at least one cutting insert (14) for chip removing machining, said drill (1) being provided with at least one chip flute (6) which extends in the axial direction of the drill (1). The invention also relates to a countersinker (3), per se. The characterising features for the tool according to the present invention are that the countersinker (3) has means (7) that is received in the chip flute (6) and which is connected by form locking thereto. The countersinker (3) comprises two halves (5).

Description: TOOL AND COUNTERSINKER FOR CHIP REMOVING MACHINING Technical field of the invention The present invention relates to a tool for chip removing machining, said tool comprising a drill and a countersinker mounted thereto, which has at least one cutting insert for chip removing machining, said drill being provided with at least one chip flute which extends in the axial direction of the drill. The invention also relates to a countersinker, per se. Prior art Through US-A-3,575,520 is previously known a tool in the shape of a drill, on which a countersinker is provided. The countersinker has an internal hole and a radial slot that extends from the internal hole to the external peripheral surface. The diameter of the internal hole of the countersinker conforms in principle to the external diameter of the drill. The radial slot allows the internal diameter of the countersinker to be somewhat widened, which in turn allows the countersinker to be pushed onto the drill in its axial direction. The countersinker is fixed on the drill by a screw in the area of the radial slot clamping the countersinker around the drill, i.e. the countersinker is fixed relative to the drill by means of friction between the internal hole of the countersinker and the peripheral surface of the drill. Through US-A-3,635,573 is known a tool in the shape of a drill, on which a countersinker is provided. The countersinker has an internal hole, which has a diameter that is somewhat larger than the external diameter of the drill. This means that the countersinker can be mounted on the drill by pushing it on the drill in its axial direction. Fixation of the countersinker, relative to the drill, is made through a substantially radially directed screw that extends through the wall of the countersinker and is received at its free end by a chip flute of the drill. Thereby the countersinker is fixed relative to the drill both in axial and circumferential direction. A general problem of the above described countersinks is that since the internal hole of each countersinker is circular and the drill is provided with a number chip flutes spaces will be formed between the internal bore wall of the countersinker and the chip flutes, such that chips will frequently get stuck in said spaces. This leads to chip stopping. SE-C1 -62052 discloses a one-piece countersinker held to the drill by means of a screw. The known countersinker needs bushings to remain in the wanted axial position. Objects of the invention A primary object of the present invention is to provide a tool and a countersinker of the above-captioned type, wherein the tool carrying the countersinker to the utmost possible extent does not lead to chip stopping. Still another object of the present invention is to provide a tool where driving of the countersinker will depend on contact between co-operative surfaces, and not through friction. Still another object of the present invention is to provide a tool where cutting inserts of the countersinker will obtain an exact positioning in the axial and circumferential direction of the drill. Still another object of the present invention is to provide a tool where the countersinker shall have a relatively low weight. At least the primary object of the present invention is realized by means of a tool and a countersinker that have obtained the features of the appended independent claims. Preferred embodiments of the invention are defined in the dependent claims. Brief description of the drawings An embodiment of the invention is described below with reference to enclosed drawings, where: Fig. 1 shows a perspective view of a tool according to the present invention, i.e. a drill, on which a countersinker is mounted, Fig. 2 shows a perspective view of a countersinker according to the present invention, Fig. 3 shows a perspective view of a half of the countersinker according to Fig. 2, Fig. 4 shows a cross-section through the countersinker according to Fig. 2, wherein the cross-section lies in a plane perpendicular to the axis of rotation of the drill in Fig. 1 , Fig. 5 shows a side view of the countersinker according to Fig. 2, as viewed towards a longer side of the countersinker, Fig. 6 shows an end view of the countersinker according to Fig. 2, as viewed towards the end which is provided with cutting inserts, and Fig. 7 shows a side view of the countersinker according to Fig. 2, as viewed towards a shorter side of the countersinker. Detailed description of a preferred embodiment of the invention The in Fig. 1 shown tool according to the present invention comprises according to the shown embodiment a conventional helix drill 1 , which has a tool part 2 as well as a shank 4, which is intended to be received in a holder (not shown) of a machine tool. A number of chip flutes 6 are formed in the tool part 2, two pieces in the shown embodiment, which run helically along the tool part 2. A countersinker 3 according to the present invention is provided on the tool part 2. The countersinker 3 according to the present invention shown in Figs. 1- 7 comprises two identical halves 5, of which only one is shown in Fig. 3. Each half 5 has a first joining portion 8a and a second joining portion 8b, which in each half 5 are mutually connected by a connection portion 7. Each half 5 has a first through hole 9 in the first joining portion 8a and a second through hole 10 in the second joining portion 8b. The first or the second through hole 9 and 10, respectively, is intended to receive, together with the opposite, co-operative hole 10 and 9, respectively, of the second half 1, a first screw 11, see Fig. 2. Thereby is understood that the first through hole 9 is internally threaded. The first joining portion 8a of each half 5 also has a cutting insert pocket 12, see Fig. 3, with an associated internally threaded third hole 13. In the insert pocket 12 a cemented carbide cutting insert 14 is received and secured by means of a second screw 15, which extends into in the third hole 13. The joining portion 8a is provided with a collar 16 at the side facing away from the insert pocket 12, which collar is compounded of three substantially straight portions. The collar 16 constitutes in principle an extension of the external bordering surfaces of the first joining portion 3. The second joining portion 8b has a notch 17 at the same side of the half 5 as the collar 16, where material has been removed along the three external edges of the second joining portion 8b. The collar 16 is received by the notch 17 in an assembled state of the both halves 5, see Fig. 4, whereby a so called labyrinth seal is formed, which in an efficient manner prevents chips from enter in between the halves 5. The connection portion 7 of each of the halves 5 generally has a shape that corresponds to a part of the helical chip flutes 6 of the tool part 2. The connection portion 7 comprises a convex surface 18, see Fig. 3, which extends helically in the axial direction of the drill 1 when the countersinker 3 is mounted to the drill 1. The convex surface 18 is situated at the side of the countersinker 3 that in assembled state thereof is facing towards the drill 1. The connection portion 7 also comprises a concave surface 19, see Fig. 2, which extends helically in the axial direction of the drill 1 when the countersinker 3 is mounted to the drill 1. The concave surface 19 is situated at the side of the countersinker 3 that in assembled state thereof faces away from the drill 1. Consequently, the convex surface 18, in assembled state of the countersinker 3, will be form locked to a chip flute 6 of the drill 1 to which the countersinker 3 is mounted. From Fig. 1 is evident how the connection portion 7 is received in a chip flute 6 of the helical drill 1 forming part of the tool according to the present invention. When mounting the countersinker 3 to the drill 1 the first screws 11 are unscrewn such that the available space between the halves 5 becomes somewhat enlarged. Thereby it is possible to "screw" the countersinker 3 onto the drill 1 from its free end, whereby the displacement of the countersinker 3, along the axial direction the drill 1 , continues until the countersinker 3 has assumed the wanted position on the tool part 2. Subsequently, the first screws 11 are tightened and the countersinker 3 is fixed axially and circumferentially on the tool part 2 of the drill 1. Thereby, the connection portion 7 of each half 5 will be received by the associated chip flute 6 of the helix drill 1 and the convex surface 18 comes into form locked abutment against the associated chip flute 6. Thereby, entering of chips in between the countersinker 3 and the drill 1 is prevented in an extremely effective manner. The associated concave surface 19, at the external surface of the countersinker 3, thereby will serve as a chip flute, i.e. the concave surface 19 forms in principle, an extension of the associated chip flute 6 at the external surface of the countersinker 3. The connection portion 7 is form locked and received in an associated chip flute 6 in connection with fixation of the countersinker 3 on the drill 1 by tightening of the first screws 11 , which causes an extraordinary reliable driving of the countersinker 3 when the drill 1 rotates. Through the compulsive guiding between the chip flute 6 and the connection portion 7 is ensured that the cutting inserts 14 of the countersinker 3 are always situated at a protruding land of the drill 1. The fact that the countersinker 3 is not rotation symmetrical but has a generally elongated flat shape entails that its weight is reduced compared to a rotation symmetrical countersinker. According to the shown embodiment the countersinker 3 is provided with two diametrically oppositely positioned cutting inserts 14, which are fixed in their insert pockets by means of second screws 15. In the operative position of the tool according to the present invention, i.e. when the drill 1 generates a hole, the cutting inserts 14 will during the end of the machining operation cause a countersink or chamfer around the hole. Chips are generated during the entire machining operation and these chips are transported in the chip flutes 6, from the drill tip in direction towards the shank. At the end of the machining operation also the cutting inserts 14 will generate chips, which likewise shall be transported away from the cutting inserts 14. Most chips shall pass the countersinker 3, said chips which are transported in the chip flutes 6, i.e. the chips which have been generated by the drill tip, will be guided past the countersinker 3 via the concave surface 19, which in principle constitutes an extension of the associated chip flute 6. The chips that are generated by the cutting inserts 14 will generally not need any chip flutes. Since the connection portion 7 in which the concave surface 19 is included, is connected by form-locking to the associated chip flute 6 via the convex surface 18 it is in principle no risk for chip stopping at the interface between the drill 1 and the countersinker 3. With the expression "form locked" or similar in the present invention patent application shall be understood that the cooperating surfaces do not need to abut absolutely tightly against each other but that there can be a gap between portions of the cooperating surfaces. It shall be noted in this connection that co- operation between the discussed surfaces must cause an adequate fixation of the countersinker 3 on the drill 1 , both in the axial and circumferential direction of the drill 1. Modifications of the invention According to the above described embodiment of a tool according to the present invention it comprises a conventional helix drill 1 , i.e. the chip flutes 6 extends helically in the longitudinal direction of the drill 1. However one can within the framework of the present invention conceive that the tool comprises also other types of drills, for example those with straight chip flutes which extend in the axial direction of the drill. Naturally, an adaptation of the countersinker according to the present invention must be done, foremost of the connection portion, depending on which type of drill on which the countersinker shall be mounted. According to the above-described embodiment the countersinker 3 is shaped such to cooperate with two chip flutes 6. However within the framework of the present invention the countersinker can be formed such to cooperate with another number of chip flutes, naturally depending on how many chip flutes the drill has on which the countersinker shall be mounted. According to the above-described embodiment of the countersinker according to the present invention this is provided with two diametrically oppositely positioned cutting inserts 14. However one can within the framework of invention conceive that the countersinker is provided with only one cutting insert, whereby in that case there can arise problems with the balance of the tool when it is in operative situation. According to the above-described embodiment the countersinker 3 consists of two identical halves 5, which are mutually connected by means of two screws 11. However, one can within the framework of the present invention also conceive that the halves are not completely identical and in that they are mutually connected with a hinge mounting at one end of the countersinker and in that a screw or similar connects the halves at the area of the other end of the countersinker.

Claims: Claims 1. Tool for chip removing machining, said tool comprising a drill (1) and a countersinker (3) mounted thereto, which has at least one cutting insert (14) for chip removing machining, said drill (1) being provided with at least one chip flute (6) which extends in the axial direction of the drill (1), characterized in that the countersinker (3) has means (7) which is received by the chip flute (6) and said means being connected by form locking to the chip flute (6) and in that the countersinker (3) comprises two halves (5). 2. Tool according to claim 1 , characterized in that the halves (5) are identical, and in that each half (5) has two joining portions (8a, 8b) and an intermediate connection portion (7), which constitutes the means received by the chip flute (6). 3. Tool according to claim 2, characterized in that the halves (5) are fixed to the drill (1) by means of screws (11) connecting the halves (5). 4. Tool according to claim 3, characterized in that the connection portion (7) has an against the chip flute (6) connecting convex surface (18) and an opposite surface (19), which in principle forms a continuation of the chip flute (6). 5. Tool according to anyone of the preceding claims, characterized in that the drill (1) consists of a helix drill with at least one helically formed chip flute (6). 6. Tool according to anyone of the preceding claims, characterized in that the countersinker (3) has two cutting inserts (14) for chip removing machining, which are diametrically oppositely positioned with regard to the axis of rotation of the tool. 7. Countersinker (3), which is intended to be mounted on a drill (1) for chip removing machining, said countersinker (3) having at least one cutting insert (14) for chip removing machining, characterized in that the countersinker (3) has means (7) which is intended to be received in a chip flute (6) of the drill (1) when the countersinker (3) is mounted thereto, and in that in said mounted situation, means (7) is connected by form locking to the chip flute (6) and in that the countersinker (3) comprises two halves (5). 8. Countersinker (3) according to claim 7, characterized in that the halves (5) are identical, and in that each half (5) has two joining portions (8a, 8b) and an intermediate connection portion (7), which constitutes the means which is intended to be received by the chip flute (6) when the countersinker (3) is mounted on a drill (1). 9. Countersinker (3) according to claim 8, characterized in that the connection portion (7) in a mounted position of the countersinker (3) on the drill (1) has a towards the chip flute (6) connecting convex surface (18) and an opposite surface (19), which in principle constitutes an extension of the chip flute (6) when the countersinker (3) is mounted on the drill (1). 10. Countersinker (3) according to claim 8 or 9, characterized in that a first joining portion (8a) has a collar (16), that a second joining portion (8b) has a notch (17), and in that the collar (16) and the notch (17) are intended to cooperate, for achieving a labyrinth seal between the halves (5), when the countersinker (3) is mounted to the drill (1).

Inventors: KARLSSON RONNY, KARLSSON, RONNY
Applicants: SECO TOOLS AB
Application year: 2001
Main classification: B23B51
IPC codes: B23B51