METHOD AND DEVICE FOR CONNECTING A HOLDER BODY WITH A TOOL HEAD

Abstract: The present invention refers to a method and a device for connecting a holder body (10) with a tool head (26), a plug (11) of the tool body (10) being inserted in a recess of the tool head (26). The device according to the invention also has a draw bar (14) arranged adjacent to the plug (11), said draw bar comprising a head (24) and a portion (25) tapering away from the head (24), means (18) for displacing the draw bar (14) in its longitudinal direction relative to the holder body (10). Characterizing for the invention is that clamping jaws (13) first are given a radial outwardly directed displacement and then an axial displacement until the tool head (26) is clamped against the holder body (10).

Description: This invention refers to a method and a device for connecting a holder body with a tool head, a plug of the holder body being inserted in a recess of the tool head, and clamping jaws being arranged adjacent to the plug. The device according to the invention also has a draw bar provided in connection with the plug, said draw bar having a head and a portion tapering from the head, and means for displacing the draw bar in its longitudinal direction relative to the holder body, and said clamping jaws being arranged adjacent to the draw bar, said clamping jaws having transverse to and along the longitudinal direction of the draw bar displacable portions. From e g US-A-4 406 195 it is known a device of the type mentioned above. However, said device having obvious disadvantages due to the fact that the clamping force transmitted to the tool head has a radial component of considerable magnitude. The device according to US-A-4 406 195 also causes great friction losses between the draw bar, the clamping pins and the tool head. From DE-A-32 43 948 it is known a device having clamping jaws that cooperate with a draw bar. Upon activation said clamping jaws are displaced radially towards each other and eventually perform a clamping action upon a central spigot. The aim of the present invention is to disclose a method and a device of the type mentioned above, the clamping force mainly having axial direction and the friction losses between cooperating force transmitting means are eleminated. The aim of the present invention is realized by a method and a device that have been given the characteristics of the appending claims. Below an embodiment of the invention will be described, reference being made to the accompanying drawings, where Fig 1 shows a longitudinal section of an embodiment according to the invention; Fig. 2 shows a section along II-II in Fig 1; Fig. 3 shows a section along III-III in Fig 1; Fig 4 shows an initial phase of a connection between a tool head and a holder body by means of the device according to the invention; and Fig 5 shows the final connection between a tool head and a holder body by means of a device according to the invention. The device according to the invention as disclosed in Figs 1-5 comprise a holder body 10, that has a plug 11. An internal recess 12, preferably with circular cross-section, is provided in the plug 11. Three clamping jaws 13 and an intermediate portion 14a of a draw bar 14 are received in the recess 12. The longitudinal centre axis for the plug 11 and the draw bar 14 is designed by reference numeral 15. From the bottom of the recess 12 a boring 16 continues, said boring having reduced diameter relative to the recess 12 in a direction from the plug 11. The boring 16 emerges in a space 17 in the holder body 10. An eccentric mechanism 18 is provided in said space 17 and connected to the draw bar 14, e.g. by means of a thread connection 19. When the eccentric mechanism 18 is activated the draw bar 14 is given a displacement towards or away from the space 17. As is most appearent from the Figures 1, 4 and 5 the clamping jaws 13 are L-shaped, the stem 13a of the L extends down into the recess 12 along the draw bar 14 while the shank 13b of the L extends radially away from the draw bar in a direction transverse to the longitudinal direction of the stem 13a. In the disclosed embodiment both the stem 13a and the shank 13b have a shape that tapers towards their joining point, seen in a plane through a clamping jaw 13 and the centre axis 15 of the plug 11. In the plug 11 slots 20 are provided, said slots extend from the free end of the plug 11 and in axial direction of the plug 11 a limited distance. The width of the slots 20 in the tangential direction of the plug 11 is somewhat bigger than the width of the shank 13b of the clamping jaws 13 in order to make it possible to displace them out through the slots 20. The stems 13a of the clamping jaws 13 have on their side that is directed from the intermediate portion 14a of the draw bar 14 grooves 21 that have an extension transverse to the longitudinal direction of the stems 13a. In the disclosed embodiment two grooves 21 are arranged on each stem 13a. A resilient O-ring 22 is received in associated grooves 21 of the stems 13a. This means that in the disclosed embodiment each O-ring 22 passes through three grooves 21. The O-rings 22 are given such a diameter that they are only slightly pre-stressed in the position of the clamping jaws 13 according to Fig 1. At the bottom of the recess 12 a further resilient O-ring 23 is located, said O-ring supporting the clamping jaws 13. The draw bar 14 has a head 24 at its end that is directed from the plug 11. A portion 25 that tapers from the head, preferably conically, constitutes a transition between the head 24 and the intermediate portion 14a of the draw bar 14. In Figs 4 and 5 a tool head 26 is drawn with dotted lines. This tool head supports in the disclosed embodiment a cutting insert 27. Within the scope of the claims other types of tool heads, e.g. a milling cutter, can be used. The tool head 26 has an axially extending through hole 28 that has a diameter that corresponds to the diameter of the plug 11, i.e. the hole 28 has a so-called slide fit relative to the plug 11. At the end of the hole 28 that is directed towards the cutting insert 27, said hole 28 has a portion 29 with a greater diameter than the rest of the hole 28. In the transition between the portion 29 and the rest of the hole 28 a step 30 is provided, said step having an extension in radial direction relative to the centre axis of the hole 28, said axis coincides with the centre axis 15 of the plug 11 and the draw bar 14. When the tool head 26 is to be connected to the holder body 10 the head 26 is pushed on the plug 11, said plug being received in the hole 28. The clamping mechanism itself is in the position according to Fig 1. In order to activate the device according to the invention the draw bar 14 is displaced in direction towards the space 17. This displacement is realized by means of the eccentric mechanism 18. In the initial phase of the displacement of the draw bar 14 in direction towards the space 17 the portion 25 will cooperate with the L-shaped clamping jaws 13 so that their shanks 13b are displaced radially outwards to the position of Fig 4 where the shanks extend through the slots 20. This radial displacement of the shanks 13b of the clamping jaws 13 is in the disclosed embodiment realized through rotation of the stem 13a around its contact point against the recess 12. In the second phase of the displacement of the draw bar 14 in direction towards the space 17 there is a cooperation between the head 24 itself and the shank 13b that results in an axial displacement of the clamping jaws 13 in the recess 12 in the same direction as the displacement of the draw bar 14. In connection therewith the shanks 13b of the jaws 13 come into contact with the step 30 of the tool head 26 and thereby a locking of the tool head 26 to the holder body 10 is carried out. In order to guarantee that any rotation of the tool head 26 relative the holder body 10 not takes place a wedge 31 of the holder body 10 is intended to cooperate with a groove 32 in the tool head 26. The force that presses the shanks 13b against the step 30 is contolled by means of the eccentric mechanism 18 and can of course be varied according to requirements. As especially is appearant from Fig 5 a prolongation of the O-rings 22 and a compression of the O-ring 23 in its cross-sectional direction occur when connection is effected. When the connection between the tool head 26 and the holder body 10 has expired the O-rings 22 and 23 will cause the clamping jaws to assume the position disclosed in Fig 1. According to the disclosed preferred embodiment the stems 13a and the shanks 13b of the clamping jaws 13 has a shape that tapers towards their joining point. For the stems 13a this result in the above-mentioned rotation around their contact with the recess 12 that is favourable since only the ends of the stems 13a that are directed towards the shanks 13b need to be displaced. For the shanks 13b the tapering shape means that the radially outmost portion of the shanks 13b will contact the step 30 when the clamping jaws are displaced axially. this is favourable as a bigger distance in radial direction between the clamping jaws gives a more steady anchoring of the tool head 26. Also it is avoided that the wall of the hole 28 is damaged. The invention is in no way restricted to the embodiment described above. Thus, instead of O-rings springs or the like can be used as return means for the clamping jaws 13. The tool head 26 must not be provided with a through hole 28 but it is also possible to have a recess provided with a step. The expression "tool head" is to be given a general interpretation and thus also incorporate milling heads, turning tools etc.. Also in other respects the invention can be freely varied within the scope of the appending claims.

Claims: Method to connect a holder body (10) with a tool head (26), a plug (11) of the holder body (10) being inserted in a recess of the tool head (26), clamping jaws (13) being arranged adjacent to the plug (11), characterized in that said clamping jaws being displaced in a direction transverse to the centre axis of the plug (11), whereafter the clamping jaws (13) are displaced along the direction of the centre axis of the plug (11) until the clamping jaws contact a bearing surface (30) of the tool head (26), that the displacement of the clamping jaws (13), in a direction transverse to the centre axis of the plug (11), is carried out against the action of a counter force, and that the radially outmost, in relation to the centre axis of the plug (11), portions of the clamping jaws (13) first contact the bearing surface (30) of the tool head (26). Device for connecting a holder body (10), comprising a plug (11), with a tool head (26), comprising a recess (28), said recess (28) being adapted to receive said plug (11), said holder body (10) being provided with a draw bar (14) that is arranged adjacent to the plug (11), said draw bar (14) comprising a head (24) and a portion (25) tapering from the head, and means (18) for displacing the draw bar (14) in its longitudinal direction relative to the holder body (10), and at least three adjacent to the draw bar (14) arranged clamping jaws (13) having transverse to and along the longitudinal direction of the draw bar (14) displacable portions (13b), characterized in that said clamping jaws (13), when activating the draw bar (14), are adapted to cooperate with the tapering portion (25) of the draw bar (14) so as to displace said portions (13b) radially outwardly and to cooperate with the head (24) of the draw bar (14) so as to define a radially outmost and radially fixed position of the clamping jaws (13) and effect an axial displacement of the clamping jaws (13) in an internal recess (12) of the plug (11), means (22) for applying a retaining force to the portions (13b) of the clamping jaws (13) when said portions (13b) are displaced in a direction away from the draw bar (14), that the tool head (26) has a bearing surface (30) for the clamping jaws (13) when they are in their radially outmost position, said bearing surface (30) being provided adjacent to the recess (28) and having an extension in radial direction relative to the longitudinal centre axis (15) of the recess (28). Device according to claim 2, characterized in that the clamping jaws (13) are L-shaped, the stem (13a) of the L having an extension in the longitudinal direction of the draw bar (14) and the shank (13b) of the L having an extension transverse to the longitudinal direction of the draw bar (14). Device according to claim 3, characterized in that the stems (13a) of the L-shaped clamping jaws (13), seen in a plane through a clamping jaw (13) and the centre axis (15) of the plug (11), has a towards the shank (13b) tapering shape. Device according to claim 3 or 4, characterized in that the shanks (13b) of the L-shaped clamping jaws (13), seen in a plane through a clamping jaw (13) and the centre axis (15) of the plug (11), has a towards the stem (13a) tapering shape. Device according to anyone of claims 2 - 5, characterized in that the portion (25) of the draw bar (14) has a conical envelope surface. Device according to anyone of the claims 2 - 6, characterized in that the means for applying a retaining force to the clamping jaws (13) constitutes of O-rings (22) that are received in grooves (21) in the stems (13a) of the clamping jaws (13). Device according to anyone of claims 2 - 7, characterized in that the head (24) comprises a radially outmost located portion in a plane substantially perpendicular to the longitudinal direction of the draw bar (14). Device according to anyone of claims 2 - 8, characterized in that the means for displacing the draw bar (14) is constituted of an eccentric mechanism (18).

Inventors: ANDERSSON, KJELL
Applicants: SECO TOOLS AB
Application year: 1987
Main classification: B23B29
IPC codes: B23B29