TOOL COUPLING

Abstract: The present invention relates to a tool coupling, preferably for turning tools, the tool coupling couples together a tool body (10; 23') and a part (1; 22'; 22'') which carries or constitutes cutting inserts for chip removing machining, the tool coupling comprising a male part (3; 3'), which has a first centre axis (7; 7'), and a female part (11; 11''), which has a second centre axis (13; 13''), and that the male part (3; 3') and the female part (11; 11'') are intended to be received in each other. The invention also separately relates to a male part, a female part and a cutting insert for chip removing machining. Characteristic of the invention is that the male part (3; 3') comprises a number of first teeth (5; 5') extending in the direction from the first centre axis (7, 7'), which teeth are spaced-apart from each other by a number of first recesses (9; 9') extending in the direction of the first centre axis (7; 7'), which recesses are situated between the teeth (5; 5') and interconnect the same, that the female part (11; 11'') comprises a number of second teeth (12; 12'') protruding in the direction of the second centre axis (13; 13''), which teeth are spaced-apart from each other by a number of second recesses (14; 14'') extending in the direction from the second centre axis (13; 13''), which recesses are situated between the second teeth (12; 12''), and that the driving angle ( alpha ) in the contact point between the teeth (5, 12; 5'; 12'') of the male part (3, 3') and the female part (11; 11''), respectively, is in the interval -5 DEG - +45 DEG , preferably -2 DEG - +25 DEG .

Description: TOOL COUPLING Technical Field of the Invention The present invention relates to a tool coupling, preferably for turning tools, the tool coupling couples together a fastening part denominated adaptor and a tool body which is intended to carry or by itself constitute a cutting insert for chip removing machining, the tool coupling comprises a male part, which has a first centre axis, and a female part, which has a second centre axis, and that the male part and female part are intended to be received in each other. The invention also separately relates to a male part, a female part and a cutting insert for chip removing machining. Prior Art A replaceable cutting body, a so-called loose top, that is attached to a shaft is previously known from DE-OS 34 02 547. The tool in question is especially suited for internal turning. The connection between the cutting body and the shaft is formed in such a way that three radial grooves are recessed in the end of the shaft turned towards the cutting body, while three radial ridges are arranged on the cutting body. In the active position of the connection, an axial screw extends through the cutting body and into the shaft, the ridges being received in the grooves. Thereby, a torque may be transferred from the shaft to the cutting body. By virtue of the relatively flat inclination of the co-operating flanks of the grooves and the ridges, a relatively high axial force is required between the shaft and the cutting body in order to transfer torque of the magnitude desired in this connection from the shaft to the cutting body. The high axial force may lead to an elongation of the screw. Furthermore, it is difficult to define where abutment between the ridges and grooves will take place since these have a linear extension. Aims and Features of the Invention A primary aim of the present invention is to describe a tool coupling of the kind defined in the introduction, the tool coupling being capable of transmitting large torques. Another aim of the present invention is that also at a moderate axial prestress, there is to be an exceptionally small risk of the transmission of torque failing to work. Yet another aim of the present invention is that the tool coupling should be self- centering. An additional aim of the present invention is that according to one embodiment of the tool coupling, the same is to be free of play. At least the primary aim of the present invention is realised by means of a tool coupling having the features given in the subsequent independent claim 1. Preferred embodiments of the invention are defined in the dependent claims. Short Description of the Drawings Below preferred embodiments of the tool coupling according to the present invention will be described, reference being made to the accompanying drawings, where Fig 1 shows a perspective view of a tool holder for a parting tool, said tool holder having a male part included in the tool coupling according to the present invention; Fig 2 shows a perspective view of tool body, which has a female part included in the tool coupling according to the present invention; Fig 3 shows an exploded view in perspective of the parts included in a tool, the tool having a tool coupling according to the present invention; Fig 4 shows a section along A-A in Fig 9 through a contact area between the male and female parts in an assembled state and included in the tool coupling; Fig 5 shows a planar view of a turning tool, which has a tool coupling according to the present invention; Fig 6 shows a section along B-B in Fig 5; Fig 7 shows a perspective view obliquely from below of a cutting insert which is provided with a male part which is included in a tool coupling according to the present invention; Fig 8 shows a perspective view obliquely from below of a circular cutting insert, which is provided with a female part which is included in a tool coupling according to the present invention; Fig 9 shows in detail how teeth and recesses co-operate in a tool coupling according to the present invention; and Figs 10-14 show additional embodiments of co-operating teeth and recesses, which are included in a tool coupling according to the present invention. Detailed Description of Preferred Embodiments of the Present Invention The tool illustrated in Figs 1-3 is intended to be used for, for instance, parting and grooving, said tool comprising an adaptor in the form of a tool holder 1, which is provided with a male part 3 included in the tool coupling according to the present invention, which male part will be described in more detail below. The tool holder 1 also comprises an insert seat 2 for receipt of a cutting insert (not shown) for chip removing machining. The male part 3, which is most clearly seen in Fig 1, comprises a number of first teeth 5, which are spaced-apart from each other, and which form a tangent to an imaginary circle having the centre on a first centre axis 7, and are directed away from said first centre axis 7. The first teeth 5 are spaced-apart by a number of first recesses 9, which are also spaced-apart from each other, and which form a tangent to an imaginary circle having the centre on the first centre axis 7, and are directed away from said first centre axis 7. The male part 3 preferably has a slightly conical shape, if so, the cone angle β, see Fig 4, being of the order of l°-30°, preferably 2°-14°. In the centre of the male part 3, a first internally threaded cylindrical hole 6 is recessed having the centre thereof on the first centre axis 7. In Fig 2 a tool body 10 is shown, one end of which is intended to be coupled to a machine tool. At the opposite end thereof, the tool body 10 has a female part 11 included in the tool coupling according to the present invention, which female part is formed to fit with the male part 3, i.e. the male part 3 should be received in the female part 11. Correspondingly, as for the male part 3, the female part 11 comprises a number of second teeth 12, which are spaced-apart from each other, and which form a tangent to an imaginary circle having the centre on a second centre axis 13, and are directed towards said second centre axis 13. The second teeth 12 are spaced-apart by a number of second recesses 14, which are also spaced-apart from each other, and which form a tangent to an imaginary circle having the centre on the second centre axis 13, and extend in the direction of said second centre axis 13. Preferably, also the female part 11 has a slightly conical shape, with a conicity equalling the conicity of the male part 3. In the centre of the female part 11 , a second internally threaded cylindrical hole 15 is recessed having the centre thereof on the second centre axis 13. In the embodiment according to Figs 1-3, the teeth 5, 12 have a convex free end and the recesses 9, 14 have a concave bottom. However, the shape of the teeth 5, 12 and the recesses 9, 14 may vary widely within the scope of the invention, which is illustrated in Figs 10-14. As mentioned above, the tool coupling according to the present invention comprises a male part 3 and a female part 11 , the same being formed to be received in each other and to force-wise co-operate with each other as for the transmission of torque between the tool holder 1 and the tool body 10, the first and second the centre axes 7, 13 coinciding with each other, in the assembled state of the tool coupling according to the present invention. In Fig 3, an exploded view of the tool holder 1 and the tool body 10 is shown where the same are in the position to be coupled together, i.e. the male part 3 should be received in the female part 11. In order to bring about the necessary axial force, a screw 17 is arranged, said screw 17 being provided with external threads 18, 19 at the two ends thereof. Said external threads 18, 19 co-operate with the internally threaded holes 6 and 15, respectively, at which the male part 3 will be received in the female part 11, at rotation of the screw 1, 7. Normally, in that connection, a very safe securing of the tool holder 1 in relation to the tool body 10 takes place. In Fig 4, the section A-A in Fig 9 through the contact area for the mutual abutment between the male part 3 and the female part 11 is shown, at which direct abutment takes place between the conical surfaces while there is a limited play between the surfaces of the tool coupling according to the present invention which are situated farthest away from the centre of rotation. There is a larger play between the end surface of the male part 3 and the bottom of the female part 11. This means that on additional axial displacement of the male part 3 and the female part 11 towards each other, the surfaces situated outermost from the centre of rotation will come to abutment against each other, while the opposite surfaces of the male part 3 and the female part 11 will not be in contact with each other. The fact that abutment takes place at the surfaces situated outermost from the centre of rotation, leads to an increased stability of the tool coupling being obtained, especially pertaining to bending loads, in comparison with if the opposite surfaces of the male part 3 and female part 11 abut against each other. In Figs 5 and 6 a turning tool 21' is shown, which has a triangular cutting insert 22' which is received in a insert seat in a holder 23' included in the turning tool 21'. The cutting insert 22' is in the usual way secured in the insert seat by means of a securing screw 24' extending through a central hole 25' of the cutting insert 22'. The centre of the hole 25' is situated on a centre axis T, which also is the centre axis of the screw 24'. As is seen in Fig 6, but still more clearly in Fig 7, the cutting insert 22' is provided with a male part 3' which is included in the tool coupling according to the present invention. Said male part 3' has principally the same design as the male part 3 in the embodiment according to Figs 1-4, i.e. the male part 3' comprises a number of first teeth 5', which are spaced-apart from each other, and which form a tangent to an imaginary circle having the centre on the centre axis 7', and extend in the direction away from said centre axis 7'. The first teeth 5' are spaced-apart by a number of first recesses 9', which also are spaced-apart from each other, and which form a tangent to an imaginary circle having the centre on the rotation axis T, and extend in the direction of said rotation axis T. Correspondingly, as for the male part 3, the male part 3' has a slightly conical shape. As is schematically seen in Fig 6, the insert seat of the holder 23' is provided with a female part 11', which has principally the same design as the female part 11. Thus, when the cutting insert 22' is situated in the insert seat thereof, the male part 3' of said cutting insert will be received in the female part 11' in the insert seat of the holder 23'. By tightening the securing screw 24', the male part 3' and the female part 11 ' will come into abutment against each other, preferably in the way which is illustrated in Fig 4. When the cutting insert 22' is indexed, the securing screw 24' is loosened and the cutting insert 22' is turned to a position where the male part 3' and the female part 11 ' again fit into each other. Then the securing screw 24' is retightened. In Fig 8, a circular cutting insert 22" is shown, which on the bottom side thereof is provided with a female part 11" included in a tool coupling according to the present invention, which part has principally the same design as the female part 11, i.e. the female part 11 " is provided with a number of second teeth 12", which are spaced-apart from each other, and which form a tangent to an imaginary circle having the centre on a second centre axis 13", and are directed towards said second centre axis 13". The second teeth 12" are spaced-apart by a number of second recesses 14", which also are spaced-apart from each other, and which form a tangent to an imaginary circle having the centre on the second centre axis 13", and extend in the direction of said second centre axis 13". Preferably also the female part 11" has a slightly conical shape, with a conicity which preferably equals the conicity of the female part 11. In the centre of the female part 11 ", a second internally threaded cylindrical hole 15" is recessed having the centre thereof on the second centre axis 13". The cutting insert 22" is intended to be secured in an insert seat of a holder (not shown), in said insert seat a male part being arranged having a shape fitting to the female part. The circular cutting insert 22" is secured in the insert seat in a corresponding way as the triangular cutting insert 22', i.e. by means of a securing screw (not shown). In Figs 9-14, a number of embodiments of co-operating teeth and recesses, respectively, are shown, which are included in the tool coupling according to the present invention, i.e. the illustrated tooth is normally included in a male part while the illustrated recess normally is included in a female part. In Fig 9, a detail of a tooth 5 of the male part 3 and a tooth 12 of the female part 11 are shown. In the above-described embodiments, the female part 11 applies a rotation to the male part 3 by the fact that the tooth 12 of the female part 11 is in contact with the tooth 5 of the male part 3. In doing so, one or more contact areas P arise between these co- operating teeth 5 and 12. With a driving angle , it should in this connection be understood the angle α which is formed between a line L which is perpendicular to the plane of force F in the contact area P between the teeth 5, 12 as well as a symmetry line CL for the tooth 5 of the male part 3. In Figs 10-14, the driving angles α are drawn in for different embodiments of teeth and co-operating recesses of the male part 3 and the female part 11 according to the present invention. As is seen in Figs 10-14, a tooth and the co-operating recess do not need to have a shape corresponding with each other. In this connection, the essential is that a contact area P is formed between the teeth 5 and 12, at which there in principle do not have to be any mutual abutment between the teeth and the appurtenant recess besides said contact area P. According to the invention, the driving angle α, as it is defined in Fig 9, should be in the interval -5° - +45°, preferably -2° - +25°. The number of teeth of the male part 3 ; 3 ' and the female part 11 ; 11 ' may vary between 3-12, preferably 6-8. Feasible Modifications of the Invention In the above-described embodiments, the male parts and female parts are formed with identical teeth around the entire circumference thereof. However, it is possible, within the scope of the present invention, that the teeth of the male part and the female part according to the present invention have a different design along the circumference of the male part and the female part, respectively. Thereby, a guiding of the mutual indexing of the male part and the female part can take place, i.e. they only fit together in a limited number of positions. In the above-described embodiments, all teeth have an equally large extension from the centre axis 7, 13; 7'; 13". However, it is also possible, within the scope of the present invention that some tooth or teeth have an extension from the centre axis 7, 13; 7'; 13" deviating from the other teeth. This may, for instance, be the case if the tool coupling is desired to be indexed in a special position. In the above-described embodiments, the male part 3; 3' is alternatively situated on the part of the tool which carries the cutting members/constitutes the cutting member for the chip removing machining or on the proper tool body/holder. The same is valid for the female part 11; 11". This variation of the location of the male part 3; 3' and the female part 11; 11" is general. In the above-described embodiments, the male part 3 ; 3 ' and the female part 11; 11 " are slightly conical while it within the scope of the present invention is fully possible that the male part and the female part generally are cylindrical. However, in this connection, it should be pointed out that with a cylindrical variant, it is difficult to bring about a coupling free of play, which, however, is obtained if the male part and the female part are slightly conical. Above, the tool coupling according to the present invention has been described in connection with a tool for parting and a turning tool, respectively. However, this only constitutes examples of tools where the tool coupling according to the present invention may be applied. In the introduction of the description of the present patent application, it is stated that the tool coupling according to the present invention preferably is intended for turning tools. The cutting insert illustrated in the embodiment according to Figs 5-7 is secured to a holder for turning. However, cutting inserts for chip removing which are provided with either a male part or a female part, which are included in a tool coupling according to the present invention may also be used together with rotary tools, for instance milling cutters or drills. List of reference designations 1 tool holder 2 insert seat 3 male part 5 first teeth 5' first teeth 6 first cylindrical hole 7 first centre axis T second centre axis 9 first recess 10 tool body 11 female part 11" female part 12 second teeth 12" second teeth 13 second centre axis 14 second recess 14" second recess 15 second cylindrical hole 15" second cylindrical hole 17 screw 18, 19 external threads 21' turning tool 22' triangular cutting insert 22" cylindrical cutting insert 3' holder 4' securing screw 5' central hole

Claims: Claims 1. Tool coupling, preferably for turning tools, the tool coupling couples together a fastening part denominated adaptor (10; 23') and a tool body (1) which carries or constitutes cutting inserts (22'; 22") for chip removing machining, the tool coupling comprising a male part (3; 3'), which has a first centre axis (7; 7'), and a female part (11; 11"), which has a second centre axis (13; 13"), and that the male part (3; 3') and the female part (11; 11") are intended to be received in each other, plus element (17; 24') which holds together the male parts (3, 3') and the female parts (11; 11') in the axial direction of the tool coupling, c h a r a c t e r i z e d in, that the male part (3 ; 3 ') comprises a number of first teeth (5; 5') extending in the direction from the first centre axis (7; T), which teeth are spaced-apart from each other by a number of first recesses (9; 9') extending in the direction of the first centre axis (7; ), which recesses are situated between the teeth (5; 5') and interconnect the same, that the female part (11; 11") comprises a number of second teeth (12; 12") protruding in the direction of the second centre axis (13; 13"), which teeth are spaced-apart from each other by a number of second recesses (14; 14") extending in the direction from the second centre axis (13; 13"), which recesses are situated between the second teeth (12; 12"), and that the driving angle (α) in the contact area (P) between the teeth (5, 12; 5'; 12") of the male part (3, 3') and the female part (11; 11"), respectively, is in the interval -5° - +45°, preferably -2° - +25°, and that the male part (3; 3') and the female part (11; 11 ") are slightly conical. 2. Tool coupling according to claim 1, c h ar a c t e r i z e d in, that the teeth (5, 12; 5'; 12") form a tangent to a first imaginary circle having the centre on anyone of the centre axes (7, 13; 7'; 13") and that the recesses (9, 14; 9'; 14") form a tangent to a second imaginary circle having the centre on anyone of the centre axes (7, 13; 7'; 13"). 3. Tool coupling according to one or any one of claims l or 2, c h a r a c t e r i z e d in, that the teeth (5, 12; 5'; 12") and recesses (9, 14; 9'; 14") are arranged with constant pitch around the centre axes (7, 13; 7'; 13"). 4. Tool coupling according to one or any one of claims 1-3, characterized in, that the teeth (5, 12; 5'; 12") have convex free ends, and that the recesses (9, 14; 9'; 14") have concave bottoms. 5. Male part (3; 3'), included in a tool coupling, preferably for turning tools, the male part (3; 3') having a first centre axis (7; 7'), characterized in, that the male part (3; 3') comprises a number of first teeth (5; 5') protruding in the direction from the centre axis (7; 7'), which teeth are spaced-apart from each other by a number of first recesses (9; 9') extending in the direction of the centre axis (7; 7'), which recesses are situated between the teeth (5; 5') and interconnect the same and that the male part (3; 3') is slightly conical. 6. Female part (11; 11 "), included in a tool coupling, preferably for turning tools, the female part (11; 11') having a first centre axis (13; 13"), characterized in, that the female part (11; 11") comprises a number of second teeth (12; 12") protruding in the direction of the centre axis (13; 13"), which teeth are spaced-apart from each other by a number of second recesses (14; 14") extending in the direction from the centre axis (13; 13"), which recesses are situated between the second teeth (12; 12") and interconnect the same and that the female part (11; 11") is slightly conical. 7. Cutting insert (22') for chip removing machining, which is provided with a male part (3'), which has a first centre axis (7'), characterized in, that the male part (3') comprises a number of first teeth (5') protruding in the direction from the centre axis (7'), which teeth are spaced-apart from each other by a number of first recesses (9') extending in the direction of the centre axis (7'), which recesses are situated between the teeth (5') and interconnect the same. 8. Cutting insert (22") for chip removing machining, which is provided with a female part (11 "), which has a first centre axis (13"), characterized in, that the female part (11 ") comprises a number of second teeth (12") protruding in the direction of the centre axis (13"), which teeth are spaced-apart from each other by a number of second recesses (14") extending in the direction from the centre axis (13"), which recesses are situated between the second teeth (12") and interconnect the same.

Inventors: HANSSON PER, SJOEOE STURE, HANSSON, PER, SJOEOE, STURE
Applicants: SANDVIK AB, SANDVIK AKTIEBOLAG
Application year: 2001
Main classification: B23B29
IPC codes: B23B27, B23B31