SHANK FOR A MILLING TOOL INCLUDING RECESSES FOR COOPERATION WITH A CHUCK

Abstract: The present invention relates to a shank (30; 60) for a milling tool, preferably an end mill, said shank (30; 60) including a first position (31; 61) and a second portion (32; 62), said first portion (31; 61) having at least a first recess (34; 64). The invention also relates to a coupling arrangement for the connection of a shank (30; 60) to a chuck (40; 50; 70; 80). When prior art shanks for milling tools are coupled to a chuck then the stability achieved in such a connection is not satisfying. The aim of the present invention is to increase the stability and consequently the load that the shank is subjected to. The present invention is characterized by having a transition surface (33; 63) between the first (31; 61) and the second (32; 62) portion, said first portion (31; 61) having a smaller diameter than the second portion (32; 62), said transition surface (33; 63) having an extension transverse to the longitudinal extension of the shank (30; 60). When coupled to a chuck (40; 50; 70; 80) the transition surface (33; 63) of the shank (30; 60) will cooperate with a contact surface (47; 57; 75; 85) of the chuck (40; 50; 70; 80).

Description: SHANK FOR A MILLING TOOL 12* UDING RECESSES FOR COOPERATION WITH A CHOCK The present invention relates to shank for a milling tool, preferably an end mill, said shank including a first portio 5 and a second portion, said first portion having at least a first recess. The invention also relates to a coupling arrangement between a shank for a milling tool and a chuck. Rotating tool shanks of cylindrical shape can be clamped in 10 holders of different types, e.g. Weldon-chucks and Whistlenotch-chucks. In said chucks the axial locking and the rotational driving are special for each type of holder. Examples of standard types of a Weldon-chuck and a Wistlenotch-chuck will be given below. 15 The prior art holders for cylindrical tool shanks are not stabilized to a sufficient degree. The present invention deals with designing the tool shank in such a w,ay that an increased stability is achieved also when using standard 20 holders, e.g. prior art Weldon-chucks and Whistlenotch- chucks. The aim of the present invention is achieved by a cylindrical tool shank that has been given the 25 characteristics of the appending claims. Below prior art embodiments and embodiments of the present invention will be described, reference being made to the accompanying drawings, where Fig.l shows a Weldon-chuck with a prior art shank; Fig.2 shows a Whistlenotch-chuck with a prior art 30 shank; Figs.3a-3c show different views of an embodiment of a tool shank according to the present invention; Fig.4 shows a Weldon-chuck with a shank according to Figs.3a-3c; Fig.5 shows a Wistlenotch-chuck with a shank according to Figs.3a-3c; Figs.6a-6c show different views of a further 35 embodiment of a tool shank according to the present invention; Fig.7 shows a Weldon-chuck with a shank according A to Figs.6a-6c; and Fig.8 shows a Whistlenotch-chuck with a ^ shank according to Figs.6a-6c. /08946 2 The device shown in Fig.l includes a standard chuck 10 of Weldon type and a prior art standard shank 11 that is received in a axial boring 12 of the chuck 10. A. first locking screw 13 and a second locking screw 14 are arranged in mating first and second radial borings 15 and 16 in the chuck 10, said radial borings 15 and 16 having a longitudinal extension generally transverse to the longitudinal centre axis 17 of the boring 12. Said longitudinal centre axis 17 is also the longitudinal centre axis of the chuck 10 and the shank 11 when said shank 11 is mounted in the boring 12 of the chuck 10. The locking screws 13 and 14 are externally threaded while the radial borings 15 and 16 are internally threaded. When rotating the locking screws 13 and 14 they are displaced in radial direction of the chuck 10 either inwardly or outwardly depending upon the direction of rotation of the locking screws 13 and 14. The shank 11 is provided with two recesses 18 and 19 having a certain extension both radially and axially. The recesses 18 and 19 are designed to cooperate with the locking screws 13 and 14. Before clamping the shank 11 in the boring 12 of the chuck 10 it is checked that the locking screws 13 and 14 are in a position to allow the shank 11 to be inserted in the boring 12. After the shank 11 is inserted in the boring 12 to a predetermined extent.the locking screws 13 and 14 are displaced radially inwardly by rotating the locking screws 13 and 14 in a predetermined direction. As is indicated in Fig.l the first locking screw 13 is in its active position cooperating with the recess 18 and exerting forces upon the shank 11 that will lock the shank 11 in axial direction. It is also indicated in Fig.l that the second locking screw 14 in its active position cooperates with the recess 19 and exerting a force upon the shank that will prevent said shank 11 from rotating relative to the chuck 10. 08946 3 The device in Fig.2 shows a standard chuck 20 of Whistlenotch type and a prior art standard shank 21 that is received in an axial boring 22 of the chuck 20. A locking screw 23 is received in a radial boring 24 of the chuck 20. The screw 23 is externally threaded while the radial boring 24 is internally threaded. The longitudinal axis of the locking screw 23 has an extension transverse to the longitudinal centre axis 25 of the axial boring 22. Said longitudinal centre axis 25 is also the longitudinal centre axis of the chuck 20 and the shank 21 when said shank 21 is mounted in the axial boring 22. However, the longitudinal axis of the locking screw 23 is not perpendicular to the longitudinal centre axis 25 of the chuck 20 but angled 2° to exert an axial force upon the shank 21 that is directed towards the bottom of the axial boring 22. The shank 21 has a planar recess 26 that runs generally in the longitudinal direction of the shank 21, said planar recess being angled relative to the longitudinal axis of the shank 21. By cooperation of the locking screw 23 and the recess 26 the shank 21 will be forced towards the bottom of the axial boring 22. This means that the screw 23 locks the shank 21 against axial displacement outwardly and simultanously against rotation around its longitudinal centre axis 25 relative to the chuck 20. In Figs.3a-3c an embodiment of a tool shank 30 according to the present invention is shown. The tool shank 30 has a first portion 31, hereinafter called a clamping portion, and a second portion 32, hereinafter called a machining portion that carries the cutting inserts (not shown) . The clamping portion 31 has a significantly smaller diameter than the machining portion 32. The transition between the clamping portion 31 and the machining portion 32 is in the shape of a radially extending surface 33 that is located in a plane transverse, preferably perpendicular, to the longitudinal extension of the tool shank 30. /08946 4 The clamping portion 31 is provided with a first recess 34 and a second recess 35. The first recess 34 has a sloping, preferably circumferential border wall 36. The second recess 35 includes two, preferably planar, portions 37 and 38 that are somewhat inclined relative to each other, the inclination normally being in the order of 2 β . In Fig. the shank according to Figs.3a-3c is clamped in a Weldon-chuck 40, said Weldon-chuck having an axial boring 41 and a first and a second locking screw 42 and 43, resp. , received in mating first and second radial borings 44 and 45 in the chuck 40. At their inner ends the locking screws 42 and 43 have a bevelled portion 42a and 43a, resp.. The radial borings 44 and 45 have a longitudinal extension generally transverse, preferably perpendicular, to the longitudinal centre axis 46 of the axial boring 41. Said longitudinal centre axis 46 is also the longitudinal centre axis 46 of the chuck 40 and the shank 30 when said shank 30 is mounted in the axial boring 41. The locking screws 42 and 43 are externally threaded while the radial borings 44 and 45 are internally threaded. When rotating the locking screws 42 and 43 they are displaced in radial direction of the chuck either inwardly or outwardly depending upon the direction of rotation of the locking screws 42 and 43. The chuck 40 also has a contact surface 47 at the entry of the axial boring 41, said contact surface extending transverse, preferably perpendicular, to the longitudinal centre axis 46. Before clamping the clamping portion 31 of the shank 30 in the axial boring 41 of the chuck 40 it is checked that the locking screws 42 and 43 are in such a position to allow the clamping portion 31 to be inserted in the axial boring 41 until the transition surface 33 abuts the contact surface 47 of the chuck 40. In mounted position of the shank 30 in the chuck 40 the transition surface 33 has an extension transverse, preferably perpendicular, to the longitudinal centre axis 46. When clamping is effected the locking screws 42 and 43 are displaced towards the clamping portion 31 and come into engagement with the recesses 34 and 35 resp.. It is recommendable to have the first locking screw 42 activated first. As can be learnt from Fig.4 the location of the first recess 34 is such that said first recess 34 is contacted by the bevelled portion 42a of the first locking screw 42 at the portion of the first recess 34 that is closest to the second recess 35. This means that the cooperation between the first locking screw 42 and the first recess 34 tends to force the shank 30 further to the right in Fig.4 thus establishing an increased contact pressure between the surfaces 33 and 47. The clamping of the clamping portion 31 in the axial boring 41 also involves an engagement between the second locking screw 43 and the second recess 35. Said engagement, together with the engagement between the first locking screw 42 and the first recess 34, prevents the clamping portion 31 from rotating relative to the chuck 40. The increased contact pressure referred to above results in an improved stability of the shank/chuck assembly that allows a load increase in the range of 50%. For a tool being subjected to radially forces, e.g. a milling tool, this means that the cutting depth can be increased by at least 50% before unacceptable vibrations arise. In Fig.5 the same shank 30 as in Fig.4 is clamped in a chuck 50 of so-called Whistlenotch type. The chuck 50 has an axial boring 51 and a first and a second locking screw 52 and 53, resp., received in mating first and second radial borings 54 and 55 in the chuck 50. At their inner ends the locking screws 52 and 53 have a bevelled portion 52a and 53a, resp.. The radial borings 54 and 55 have a longitudinal extension generally transverse to the longitudinal centre axis 56 of the axial boring 51. Said longitudinal centre axis 56 is also the longitudinal centre axis of the chuck 50 and the 3/08946 6 shank 30 when said shank 30 is mounted in the axial boring 51. However, the longitudinal extension of the radial borings 54 and 55 is not perpendicular to the longitudinal centre axis 56 but offset an angle of 2 β from the perpendicular direction. The inclination of the radial borings 54 and 55 is such that the inner end of said borings 54 and 55 is located further away from a contact surface 57 at the entry of the axial boring 51 than the outer end of said borings 54 and 55. The contact surface 57 has an extension transverse, preferably perpendicular, to the longitudinal centre axis 56. Before clamping the clamping portion 31 of the shank 30 in the axial boring 51 of the chuck 50 it is checked that the locking screws 52 and 53 are in such a position as to allow the clamping portion 31 to be inserted in the axial boring 51 until the transition surface 33 abuts the contact surface 57 of the chuck 50. In mounted position of the shank 30 in the chuck 50 the transition surface 33 has an extension transverse, preferably perpendicular, to the longitudinal centre axis 56. When clamping is effected the locking screws 52 and 53 are displaced towards the clamping portion 31 and come into engagement with the recesses 34 and 35, resp.. It is recommendable to have the first locking screw 52 activated first. As can be learnt from Fig.5 the location of the first recess 34 is such that said first recess 34 is contacted by the bevelled portion 52a of the first locking screw 52 at the portion of the first recess that is closest to the second recess 35. This means that the cooperation between the first locking screw 52 and the first recess 34 tends to force the shank 30 further to the right in Fig.5 thus establishing an increased contact pressure between the surfaces 33 and 57. The clamping of the clamping portion 31 in the axial boring 51 also involves an engagement between the second locking screw 53 and the second recess 35. Said engagement, together with the engagement between the first /08946 7 locking screw 52 and the first recess 34, prevents the clamping portion 31 from rotating relative to the chuck 50. Concerning the advantages of the increased contact pressure reference is made to what is said in that respect in connection with the embodiment of Fig.4. In Figs.6a-6c an embodiment of a tool shank 60 according to the present invention is shown. The tool shank 60 has a clamping portion 61 and a machining portion 62 that carries the cutting inserts (not shown) . The clamping portion 61 has a significantly smaller diameter than the machining portion 62. The transition between the clamping portion 61 and the machining portion 62 is in the shape of a radially extending surface 63 that is located in a plane transverse, preferably perpendicular, to the longitudinal extension of the tool shank 60. As a difference compared to the shank 30 the clamping portion 61 of the shank 60 is provided with only one recess 64. The recess 64 has a sloping, circumferential border wall 65. In Fig.7 the shank 60 according to Figs.6a-6c is clamped in a Weldon-chuck 70, said Weldon-chuck having an axial boring 71 and a single locking screw 72 received in a mating radial boring 73 in the chuck 70. At its inner end the locking screw 72 has a bevelled portion 72a. The radial boring 73 has a longitudinal extension generally transverse, preferably perpendicular, to the longitudinal centre axis 74 of the axial boring 71. Said longitudinal centre axis 74 is also the longitudinal centre axis of the chuck 70 and the shank 60 when said shank 60 is mounted in the axial boring 71. The locking screw 72 is externally threaded while the radial boring 73 is internally threaded. When rotating the locking screw 72 it is displaced in radial direction of the chuck 70 3/08946 8 either inwardly or outwardly depending upon the direction of rotation of the locking screw 72. The chuck 70 also has a contact surface 75 at the entry of the axial boring 71, said contact surface 75 having an extension transverse, preferably perpendicular, to the longitudinal centre axis 74. Before clamping the clamping portion 61 of the shank 60 in the axial boring 71 of the chuck 70 it is checked that the locking screw 72 is in such a position as to allow the clamping portion 61 to be inserted in the axial boring 71 until the transition surface 63 abuts the contact surface 75 of the chuck 70. In mounted position of the shank 60 in the chuck 70 the transition surface 63 has an extension transverse, preferably perpendicular, to the longitudinal centre axis 74. When clamping is effected the locking screw 72 is displaced towards the clamping portion 61 and comes into engagement with the recess 64. As can be learnt from Fig.7 the location of the recess 64 is such that said recess 64 is contacted by the bevelled portion 72a of the locking screw 72 at the portion of the recess 64 that is closest to the free end of the clamping portion 61. This means that the cooperation between the locking screw 72 and the recess 64 tends to force the shank 60 further to the right in Fig.7 thus establishing an increased contact pressure between the surfaces 63 and 75. The engagement between the locking screw 72 and the recess 64 also prevents rotation of the clamping portion 61 relative to the chuck 70. Concerning the advantages of the increased contact pressure reference is made to what is said in that respect in connection with the embodiment of Fig.4. In Fig.8 the same shank 60 as in Fig.7 is clamped in a chuck 80 of so-called Whistlenotch type, said chuck 80 having an axial boring 81 and a single locking screw 82 received in a /08946 9 mating radial boring 83 in the chuck 80. At its inner end the locking screw 82 has a bevelled portion 82a. The radial boring 83 has a longitudinal extension generally transverse to the longitudinal centre axis 84 of the axial boring 81. However, the longitudinal extension of the radial boring 83 is not perpendicular to the longitudinal centre axis 84 but offset an angle of 2" from the perpendicular direction. Said longitudinal centre axis 84 is also the longitudinal centre axis of the chuck 80 and the shank 60 when said shank 60 is mounted in the axial boring 81. The locking screw 82 is externally threaded while the radial boring 83 is internally threaded. When rotating the locking screw 82 it is displaced in radial direction of the chuck 80 either inwardly or outwardly depending upon the direction of rotation of the locking screw 82. The chuck 80 also has a contact surface 85 at the entry of the axial boring 81. Said contact surface 85 has an extension transverse, preferably perpendicular, to the longitudinal centre axis 84. Before clamping the clamping portion 61 of the shank 60 in the axial boring 81 of the chuck 80 it is checked that the locking screw 82 is in such a position as to allow the clamping portion 61 to be inserted in the axial boring 81 until the transition surface 63 abuts the contact surface 85 of the chuck 80. In mounted position of the shank 60 in the chuck 80 the transition surface 63 has an extension transverse, prefereably perpendicular, to the longitudinal centre axis 84. When clamping is effected the locking screw 82 is displaced towards the clamping portion 61 and comes into engagement with the recess 64. As can be learnt from Fig.8 the location of the recess 64 is such that said recess 64 is brought into contact with the bevelled portion 82a of the locking screw 82 at the portion of the recess 64 that is closest to the free end of the clamping portion 61. This means that the cooperation between the locking screw 82 and the recess 64 /08946 10 tends to force the shank 60 further to the right in Fig.8 thus establishing an increased contact pressure between the surfaces 63 and 85. The engagement between the locking screw 82 and the recess 64 also prevents rotation of the clamping portion 61 relative to the chuck 80. Concerning the advantages of the increased contact pressure reference is made to what is said in that respect in connection with the embodiment of Fig.4. It should also be pointed out that the different chucks shown in the appending igures are prior art standard chucks. This means that by using a shank according to the present invention in combination with prior art standard chucks significant improvements as regards stability of the shank are achieved. The invention is in no way restricted to the embodiments described above but can be freely varied within the scope of the appending claims.

Claims: 93/08946 11 Claims 1. Shank (30;60) for a milling tool, preferably an end mill, said shank (30;60) including a first portion (31;61) and a second portion (32;62), said first portion (31;61) having at least a first recess (34;64), c h a r a c t e r i z e d in that the first portion (31;61) has a smaller diameter than the second portion (32;62), that the transition between the first portion (31;61) and the second portion (32;62) includes a surface ((33;63) that extends transverse to a longitudinal extension of the shank (30;60) . 2. Shank (30;60) according to claim l, wherein said shank (30;60) has a longitudinal centre axis (46;56;74;84) , c h a r a c t e r i z e d in that the transition surface (33;63) between the first (31;61) and the second (32;62) portion extends perpendicular to the longitudinal centre axis (46;56;74;84) . 3. Shank according to claim 1 or 2, c h a r a c t e r i z e d in that the first recess (34;64) has a sloping border wall (36;65) at least in the portion that is closest to the free end of the the first portion (31;61). 4. Shank according to any of the preceding claims, c h a r a c t e r i z e d in that a second recess (35) includes two portions (37,38) that are somewhat inclined relative to each other. 5. Shank according to claim 4, c h a r a c t e r i z e d in that the inclination between the two portions (37,38) of the second recess is in the order of 2° . 6. Coupling arrangement for the connection of a shank (30;60) of a milling tool to a chuck (40;50;70;80) , said /08946 12 shank (30;60) having a first (31;61) and a second (32;62) portion, said first portion having at least a first recess (34;64), said chuck (40;50;70;80) having an axial boring (41;51;71;81) that receives the first portion (31;61) of the shank (30;60), said chuck ((40;50;70;80) having at least a first locking screw (42;52;72;82) that has a longitudinal extension generally transverse the longitudinal extension of the axial boring (41;51;71;81) , said first locking screw (42;52;72;82) being displaceable into engagement with the first recess (34;64) of the first portion (31;61) when said first portion (31;61) is received in the axial boring (41;51;71;81), c h a r a c t e r i z e d in that the transition between the first portion (31;61) and the second portion (32;62) includes a surface (33;63) that extends transverse to the longitudinal direction of the shank (30;60), that the first recess (34;64) and the first locking screw (42;52;72;82) are so oriented relative each other that when the transition surface (33;63) contacts a contact surface (47;57;75;85) of the chuck (40;50;70;80) at the entry of the axial boring (41;51;71;81) then the engagement between the first locking screw (42;52;72;82) and the first recess (34;64) will increase the contact pressure between the transition surface (33;63) and the contact surface (47;57;75;85) . 7. Coupling arrangement according to claim 6, c h a r a c t e r i z e d in that the transition surface (33;63) and the contact surface (47;57;75;85) have an extension perpendicular to a common longitudinal centre axis (46;56;74;84) of the shank (30;60) and the chuck (40;50;70;80) . 8. Coupling arrangement according to claim 6 or 7, c h a r a c t e r i z e d in that the engagement between the first locking screw (42;52;72;82) and the first recess (34;64) establishes a contact between the first locking screw (42;52;72;82) and a portion of the first recess (34;64) that is closest to the free end of the first portion (31;61) . 9. Coupling arrangement according to claim 8, c h a r a c t e r i z e d in that contact is established between a bevelled portion (42a;52a;72a;82a) at the inner end of the first locking screw (42;52;72;82) and a sloping border wall (36;65) of the first recess (34;64). 10. Coupling arrangement according to any of claims 6-9, wherein a second locking screw (43;53) of the chuck (40;50) engages a second recess (35) in the first portion (31) of the shank (30) , c h a r a c t e r i z e d in that the second recess (35) has two portions (37,38) that are inclined relative to each other, preferably in an inclination angle in the order of

Inventors: ANDERSSON KJELL, RIVIERE BERTRAND, ANDERSSON, KJELL, RIVIERE, BERTRAND
Applicants: SECO TOOLS AB
Application year: 1992
Main classification: B23C5
IPC codes: B23B31, B23C5, B23Q3