The technical field of the invention The present invention relates to a tool and a countersink for chip removing machining, according to the appended independent claims.

Through US-A-5,915, 895 is previously known a tool for drilling and chamfering, wherein the tool comprises a base body, in which a drill is received. At the end of the base body situated closest to the drill tip means are provided in order to achieve chamfering. These means are made of specially designed cutting inserts that are fixed on the base body via a screw and clamp combination. The tool according to US-A-5,915, 895 does not show any arrangement for precisely adjusting the positions of the cutting inserts.

Through US-A-5,265, 988 is previously known a tool for drilling and chamfering, wherein the tool comprises a tool holder having a chamfering head at its forward end, where two cutting blades are held, diagonally opposite to each other. A drill with a shank portion is received in the tool holder. The cutting blades are held by screw and clamp combination. The cutting blades are received in grooves that form a certain angle with the axis of rotation of the tool, wherein the cutting blades are adjustable in grooves in connection with that it is mounted on the chamfering head.

The tool according to US-A-5,265, 988 does not show any arrangement for precisely adjusting the positions of the cutting blades.

WO 95/07787 shows a tool for chip removing machining. The known tool comprises cutting inserts that are intended to perform an additional machining operation, for example chamfering or countersinking. The tool has means for adjusting the positions of the cutting insert. These means comprise a slide with a oblong hole, carrying a cutting insert. The slide can be displaced relative to a locking screw, which fixes the slide in position. The displacement of the slide occurs wholly manually.

The objects of the invention A primary object of the present invention is to provide a tool of the above-captioned type, which tool enables a precise adjustment of the cutting inserts forming a parts of the countersink to the actual operative diameter of the standard drill forming a part of the tool.

Another object of the present invention is to simplify the mounting of the countersink on the drill.

Still another object of the present invention is to achieve an infinitely variable adjustment of the cutting inserts producing the chamfer.

Still another object of the present invention is to achieve an infinitely variable adjustment of the drill depth.

At least the primary object of the present invention realized by a tool having obtained the features indicated in the subsequent independent claim 1.

Preferred embodiments of the invention are defined in the dependent claims.

Brief description of the drawings Below an embodiment of the invention will be described with reference to the enclosed drawings, wherein: Fig. 1 shows a side view of a tool according to the present invention; Fig. 2 shows a side view of the tool according to Fig. 1, however the tool being rotated 90° around its axis of rotation as compared with Fig. 1; Fig. 3 shows a cross-section along the line 111-111 in Fig. 2; Fig. 4 shows an exploded view in perspective, obliquely from the front, of the countersink forming a part of the tool according to the present invention; Fig. 5 shows an exploded view in perspective, obliquely from behind, of the countersink forming a part of the tool according to the present invention; Fig. 6 shows a cross-section along the line VI-VI in Fig. 3; and Fig. 7 shows a cross-section along the line VII-VII in Fig. 3.

Detailed description of a preferred embodiment of the invention The tool according to the present invention shown in Figs. 1-3 comprises a countersink 1, which is mounted on a drill 3, which may be of standard configuration. In the shown embodiment the drill 3 is a helix drill, which has at least one protruding land 4 and a chip flute 6.

The countersink 1 forming a part of the tool according to the present invention is shown in Figs. 1-3 and in Figs. 4 and 5. The countersink 1 comprises an anchoring portion 5 and an insert-receiving portion 7, wherein the anchoring portion 5 is provided with a male thread 9 while the insert-receiving portion 7 is provided with a female thread 10. The male thread 9 and the female thread 10 can be brought into engagement with each other during forming of a thread joint.

A collar 11 is provided in connection with the male thread 9, wherein this collar 11 will get into abutment against an end surface 12 of the insert-receiving portion 7. Thereby, a connection is achieved between the anchoring portion 5 and the insert-receiving portion 7, which can receive relatively large bending stresses.

The anchoring portion 5 is generally designed as a sleeve, which is intended to be placed over a shank portion 13, see Fig. 3, of the drill 3 that also comprises a hole-making portion 14. Along the greater part of its length the anchoring portion 5 is provided with slots 15 that alternately opens into the free end of the anchoring portions 5 and extend forwardly to the collar 11, respectively. The provision of slots 15 makes that the anchoring portion 5 becomes somewhat flexible, which facilitates attachment of the anchoring portion 5 on the shank portion 13 of the drill 3. By dividing the countersink 1 into an anchoring portion 3 and an insert- receiving portion 7 adaptation can be made to different combinations of diameters of the shank portion 13 and the hole-making portion 14.

The insert-receiving portion 7 comprises two insert pockets 20 for a cutting insert for chip removing machining, two cutting insert 21 provided in these insert pockets, first means 22 for clamping the cutting inserts 21 in the insert pockets 20 and second means 23 for adjusting the positions of the cutting inserts 21 in their respective insert pockets 20. In order to convey the tool a symmetrical counterbalance the insert pockets 20 are placed diametrically opposed with regard to the axis C-C of rotation of the tool. In the shown embodiment the insert pockets 20 are provided with first serrations 24 and the lower side of the cutting inserts 21 are provided with second serrations 25, wherein the first serrations 24 and the second serrations 25 come into engagement with each other when a cutting insert 21 is placed in its associated cutting insert pocket 20. The longitudinal direction of the first serrations 24 that coincides with the cross-sectional line VI-VI in Fig. 3, slopes a certain angle a relative to the axis C-C of rotation of the tool.

The first means for clamping a cutting insert 21 in its associated cutting insert pocket 20 is according to the shown embodiment made of a center screw 22, which is received by a center hole 26 of the cutting Insert 21. Each insert pocket 20 is also provided with a through-going first hole 27, through which the center screw 22 passes when it is in active position.

Second means 23 for adjusting of the cutting insert 21 position in its respective insert pocket 20 is provided in connection with each insert pocket 20.

Each second means 23 in the shown embodiment comprises two second and third holes 28 and 29 arranged beside each other in the insert-receiving portion 7. The holes 28 and 29 are provided in immediate connection with its associated insert pocket 20 and each having an extension longitudinally along the longitudinal direction of the first serrations 24. The second hole 28 is not threaded while the third hole 29 is threaded. In Fig. 6 it is visible that the second hole 28, in which a pin 30 or a displaceable member is received, said pin 30 having a threaded, through-going fourth hole 31 extending laterally to the longitudinal direction of the pin 30. The mutual dimensions of the second hole 28 and the pin 30 are such that the pin 30 is displaceable in the second hole 28, i. e. slide fit is present between the second hole 28 and the pin 30. The fourth hole 31 is intended to cooperate with the center screw 22, i. e. the center screw 22 can be threaded into the fourth hole 31. An adjustment screw or adjustment member 32, which likewise forms a part of the means for adjusting the cutting insert 21 positions in their respective insert pockets 20, is received in the third hole 29 and cooperates with a surface of the pin 30 that is generally lateral to the longitudinal direction of the in 30.

When a cutting insert 21 shall be fixed in its associated cutting insert pocket 20, see Figs. 6 and 7, the cutting insert 21 is placed in the insert pocket 20, whereby the first and second serrations 24,25 are brought into engagement with each other. The center screw 22 is received in the center hole 26 of the cutting insert 21, whereafter it extends through the first hole 27 in the insert pocket 20 and forms a thread joint with the fourth hole 31 in the pin 30, which is arranged in the second hole 28. Also the adjustment screw 32 is placed in the third hole 29, whereby the adjustment screw 32 is brought to abutment against the lateral surface of the pin 30.

Initially a complete tightening of the center screw 22 is not performed, which enables the pin 30 to be displaced by the adjustment screw 32 being rotated in its threaded third hole 29. Thereby, a fine adjustment of the cutting insert 21 position in the insert

pocket 20 is made possible, such that displacement of the cutting insert 21 thereby occurs in the longitudinal direction of the serrations 24,25. When the final position of the cutting insert 21 has been reached the cutting insert 21 is fixed by further tightening the center screw 22. Thereby, the displaceable member 30 is developed to be brought into a force transmitting engagement with the second means 22 for fixing the cutting insert 21.

Consequently, the tool according to the present invention comprises the above-described countersink 1 and the drill 3, on which the countersink 1 is mounted.

Thereby, the anchoring portion 5 of the countersink 1 is provided on the shank portion 13 of the drill 3, wherein the shaping of the anchoring portion 5 as a slotted sleeve-makes that the countersink 1 easily can be mounted on the drill 3 and be displaced in the longitudinal direction of the drill 3. Thereby is made sure that the nose of the cutting insert 21 facing towards of the drill 3 tip is situated in the area of the protruding land 4 of the drill 3, i. e. one nose 34 of the cutting insert 21 abuts against the protruding land 4 of the drill 3, which thus constitutes a stop abutment for the cutting insert 21. In order to still improve cooperation between the cutting insert 21 and the drill 3 the cutting insert 21 is provided with a chamfer 35 in the area of the cutting insert 21 intended to abut against the protruding land 4 of the drill 3. The chamfer 35 has an axial dimension that is substantially parallel with the axial extension of the protruding land 4. The abutments of the cutting inserts 21 against the drill 3 contribute to some degree to the stability of the free end of the drill.

The anchoring portion 5 can be displaced in axial direction relative to the drill 3 by having a flexible anchorage on the shank portion 13 of the anchoring portion 5, whereby the drill depth easily can be varied. At this displacement the nose 34 of the cutting insert 21 facing towards the drill 3 tip is positioned in connection to a protruding land 4 of the drill 3. At use of the tool according to the present invention both the anchoring portion 5 and the internally located shank portion 13 are provided in a chuck or similar. The slots 15 of the anchoring portion 5 thereby bring about that the anchoring portion 5 and the shank portion 13 will become rigid in the rotational direction relative to each other.

After performing drilling and chamfering of a number of holes normally there is a need to exchange drill. Then the anchoring portion 5 and the shank portion 13 are loosened from the chuck. Then the center screw 22 and the associated adjustment means 31,32 for the respective cutting insert 21, thereby allowing the

cutting inserts to be pushed away from the drill 3 such that it can be dismounted from the countersink 1. A new drill 3 is then mounted in the countersink 1, whereafter the cutting inserts are tightened again and are brought to abutment against the drill 3 in the above-described manner. After finely adjusting the positions of the cutting inserts 21 the tool according to the present invention again ready to be used.

Conceivable modifications of the invention In the above-described embodiment of the tool the countersink 1 is mounted on a helix drill 3, which seems be the most preferred combination. However, one may within the limits of the present invention also imagine the countersink 1 being mounted on another type of drill.

In the above-described embodiment the center screws 22 clamp the cutting inserts 21. Within the limits of the invention one can however imagine that the cutting inserts are clamped by an alternative method, wherein in exemplifying and but not limiting purpose top clamps can be mentioned.