This invention relates to a tool assembly formed essentially of a basic tool holder and a tool head in which a cutting tool--such as a drill or a cutting insert--is immobilized and which is coupled to the basic tool holder by a cylindrical fitting and mechanical clamping (locking) elements. The invention is in particular concerned with metal cutting tools which are essentially formed of a basic tool holder and a cutting tool head. The loosening and tightening of the clamping elements may be effected manually or mechanically.
Mechanically coupled cutting tools of the above-outlined type are widely known; among these are, for example, boring bars, that is, tools adapted for internal turning and having replaceable boring heads which are connected with the boring bar by means of a dovetail or a cylindrical fitting. Couplings of this type are disadvantageous in that in general they require additional tightening screws which, for replacing the head, have to be manually loosened and then tightened. Consequently, this type of coupling is not adapted for an automated machining cycle which includes robot-performed replacement of the tool head.
It has already been proposed to equip numerically controlled machine tools with tool changing devices which provide that the cutting tools, including the tool holders, can be moved manually or by a tool changer from a work position, such as a tool turret or a work spindle, to a tool magazine where they are deposited and then another tool is brought into the work position. In such assemblies, however, the machining cycle can be automated only to a limited extent, because for each changing of the cutting tool every time the expensive and usually very heavy basic tool holder has to be replaced too. Because of this kind of replacement process, the machine tools cannot be utilized in an optimal manner. It is a further disadvantage of the machine tools outlined above that a manual tool replacement is time-consuming and circumstantial.
There has been, however, proposed a fully automated machine cycle with cutting insert exchanger in turning operations. Upon a control command, the cutting insert exchanger automatically substitutes a new cutting insert from a magazine for the used cutting insert after the service time of the latter has lapsed. Such apparatuses, however, can be used only in special operations and are limited to the use of cutting tools of predetermined uniform configurations and dimensions. A replacement of different cutting tools is thus not feasible with such an arrangement. In machining runs, however, a plurality of different operations have to be performed, such as internal or external machining, threading drilling, etc.