|1.||A tool for machining and/or chucking a workpiece, determined .that its one end is attachable to a spindle of a rototable machine (12) where said end has cylindrical characteristic and is designed to be attached to said spindle c h a r a c t e¬ r i z e d in, that the tool is tubeshaped at the other end, where it is slotted insuch a way that a plurality of fingers (14) are formed which have an internal and external taper (16, 18) at which the fingers within their length are radially displaced and surrounded by a screwed collar 20) acting against the external taper (16) for radial displacement of the fingers inwards, or together with a pressure plate (22) giving the fingers a radial displacement outwards by activation of a screwed device (20, 26) cooperating with the internal taper (18) and the finger ends are edged for machining operations.|
|2.||A tool as claimed in claim 1 c h a r a c t e r i z e d in that every finger at its free end is edged for machining.|
|3.||A tool as claimed in claim 1 c h a r a c t e r i z e d in that the free ends of the fingers, the external or/and the internal surfaces are profiled to provide good gripping of a workpiece.|
|4.||A tool as claimed in claim 3 c h a r a c t e r i z e d in that the profiled surfaces have a conventional thread (14).|
|5.||A tool as claimed in some of the above claims c h a r a c t e r¬ i z e d in that at least one of said fingers (48) is removable.|
|6.||A tool as claimed in at least one of above claims c h a r a c t e r i z e d in that it contains at least one preferable in front of said axial positioned flat cutting drill insert (40), a centre drill (42) or a spring loaded centering dowel (38).|
The object of the tool according to the invention is to simplify chucking of a workpiece that separate tools are no longer needed. The recess for chucking is accomplished by the tool itself in a precise way, after which the tool can chuck with safe grip.
After turning is done the workpiece can be removed from the tool and recentred with good repeating centricity. Another object with the invention is that the recess accomplished is looking attractive.
The tool can also be used as an adjustable holesaw or a flat cutting drill.
The invention will now be more fully described with reference to accompanying drawings.
Fig. 1 shows perspectively the tool cylinder 10 and the screwed collar 20 and a recess at the bottom of a bowl 24.
Fig. 2, 5, 6 and 7 show tool cross sectional.
Fig. 2 shows the tool assembled with the pressure plate 22, screw 26 and a spring loaded centering dowel.
Fig. 3 shows the pressure plate separated.
Fig 4 shows how the tool can grip in contraction and expansion mode.
Fig. 5 and 6 show chucking of a cylindrical workpiece 36 in combination with plate 22, screw 26, a supporting face plate 34 and screwed collar with a taper 28.
Fig. 7 shows the flat cutting drill-insert 40 assembled with the centre drill 42.
-Fig. 8 shows a jaw chuck 46 tipped with cutting bits 48.
The tool according to the invention is built up around a body 10 which at one- end is attachable to a rotatable machine. The shown end 12 relates to DIN 800, has a radial guide and a thread 32. The opposite end is axially slotted and provided with holesaw fingers 14, which have a fine thread both internally and externally deter¬ mined for forced drilling at low speed and/or for safe gripping. The fingers 14 have at each front end an axially positioned cutting edge. At their rear side the fingers are tapered both on the inside 18 and outside 16. On the body's external thread 30 a screwed collar 20 is screwed against the external taper 16 whereby the fingers contract.
Fig. 2 shows the pressure plate 22 assembled and now the screwed collar 20 pressed against the noses of the plate 21 whereby the inside of the pressure plate is pressed on to the taper 18 where¬ after the fingers expand. The radial displacements of the fingers result in a variation of diameter when drilling alternatively chucking when turning. The spring loaded centering dowel 38 can be used both for drilling and chucking.
When chucking a cylindrical workpiece 36 in expanding mode the screwed collar 20 is replaced by a face plate 34 alternatively a screwed collar with a taper 28. The expansion of the fingers is obtained when the screw 26 is pressed against the pressure plate 22.
Fig. 7 is showing the tool as a drill only. The flat cutting drill insert 40 is assembled on screw 26 which also carries the centre drill 42. In order to avoid unwanted movement of screwed collar 20 this can be secured by means of a nut 44. Alternatively the function of drilling and chucking can be obtained by assembling of at least one profiled finger 48 to jaws 46 to a conventional jaw chuck.