Cutting by use of rotating axially moving tool – Tool of specific diverse material
Patent
1997-04-02
1999-05-18
Howell, Daniel W.
Cutting by use of rotating axially moving tool
Tool of specific diverse material
408230, 408233, 408713, B23B51/02
Patent
active
059044551
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a drill having the characteristics listed in the preamble to claim 1, Such a drill is disclosed in EP-B1-172 148. In this drill, the drill point part is embodied in several parts. Moreover, it is clamped by means of clamping screws penetrating the shaft groove radially.
The object of the invention is to provide a drill of the type mentioned at the beginning with a clamping device that is improved in terms of efficiency and is easier to operate. This objective is attained through clamping the drill point part on its side faces which correspond to the flanks of the groove in a force-locking manner by an insertion-clamping fit in the shaft groove owing to resilient pressure exerted by the groove flanks.
The solution is characterized by "self-grip" features. The drill point part only needs to be Inserted into the shaft groove. The dimensional relations between the clamped wall thickness of the drill point part and the distance between the two groove flanks ensure firm clamping. The drill point part is supported in the advance direction of the drill through the base of the shaft groove.
Providing an additional guide face in a radial direction between the flanks of the shaft groove and the clamping grooves which springs back in an approximately radial direction towards the outside and runs basically parallel to the drill shaft axis and forms an obtuse angle with the groove flanks, and providing counter guide faces on the drill point part corresponding to and opposite the guide faces on corresponding shoulders which shoulders protrude radially toward the outside so that the drill point part is clamped with these shoulders in a force-locking manner in addition between the counter guide faces improves the clamping. The clamping pressure introduced into the additional guide faces, together with the pressure exerted by the groove flanks, create resultant pressure, by means of which the drill point part is pressed in particular in the radially outer regions towards the flank walls of the shaft groove.
Providing a slit in the drill shaft approximately in the middle and substantially parallel to the shaft groove, and starting from the groove base in an axial direction allows for the flexible clamping pressure behavior to be adjusted. Specifically, the slit can have a depth which extends in an axial direction for adapting the springing behavior of the groove flanks or of the guide faces assigned to them.
Providing a slit in the base of the groove approximately centered and substantially parallel to the shaft groove, which slit extends substantially in the axial direction, and providing a groove base that rises on both sides starting from the groove flanks radially toward the inside, in the direction of the axial slit, and thereby forming a roof-form, and providing a base surface of the drill point part which is hollowed out with a slightly smaller ridge angle of a roof form and clamping, in particular screwing, the drill point part in an axial direction on the drill shaft in such a manner against the slit that the clamping pressure exerts an opposing clamping pressure on the flanks of the shaft groove, is a modified embodiment for attaining the objective of the invention, which is not or is less dependent on the existence of a flexible clamping pressure exerted by the groove flanks on the drill point insert. Here, the radial clamping pressure taking effect an the drill point part can be generated or supported through axial bracing of the drill point part, and for this solution, the additional guide faces described above are not required, even If they could advantageously be used in this embodiment.
Providing a positioning screw approximately concentric to the shaft axis, penetrating the shaft slit and protruding with its screw threading into the drill point part, which positioning screw is accessible for operational purposes from the rear shaft end, contains a solution for clamping the drill point part in an easily manageable manner. Further characteristics of the embodiment are described below.
REFERENCES:
patent: 4728231 (1988-03-01), Nagatoshi et al.
patent: 4744704 (1988-05-01), Galvefors
patent: 5154549 (1992-10-01), Isobe et al.
patent: 5228812 (1993-07-01), Noguchi et al.
Jager Horst
Krenzer Ulrich
Mueller Gebhard
Howell Daniel W.
Kennametal Hertel AG
Prizzi John J.
Tabaddor Rouz
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