Drilling systems by vibrations
BACKGROUND OF THE INVENTION 
     The present invention concerns a drilling systems operable by vibrations. 
     In this kind of system, a tool such as the driller of the type described notably in the French Pat. No. 82/18545, is inserted into a housing set obliquely in relation to the axis of the tool-holder, itself equipped with a device generating vibrations, for instance a pneumatic turbine, whereof the rotor comprises an unbalance and whereof the rotation at very high speed generates vibrations of about the frequency 300 HZ. 
     A device known for fastening the tool, particularly a drill, in its housing consists of a socket co-axial to the tool-holder, and that, by screwing towards above the external form of the said tool-holder, till the contact of the drill determines the blocking of the same. 
     This device shows a disadvantage that is inherent in the system itself. Namely, by functionning of this system through vibrations, these ones cause inevitably the unscrewing of this socket and therefore the unclamping of the driller that, even if not freed from its housing, receives no longer the vibrations achieving its efficiency. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to remedy this disadvantage. It consists in securing the blocking of the tool in its housing through a first element that is forcibly driven on to the conical seat of the tool-holder, this first element being itself kept in the place by a socket similar to the socket of the known system. Thus it is obtained an effect of counter-nut or lock nut of the second element upon the first, securing its immobility and therefore the locking of the drill in place, in spite of vibrations to which it is submitted. 
     The fit of the first element on the tool-holder can simply be made by means of friction upon its seat, but preferably it is made by screwing, even in the same direction as the socket, in the same way as the real assemblage nut/counter-nut. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention is better understood by the attached drawing, whereof the single FIGURE, is a sectional view along the axial symmetry plane of the system according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     On this drawing are shown the tool-holder 1 comprising on its posterior portion the mechanism 2 generating vibrations, as type already known in itself, for instance a pneumatic turbine with unbalance In the housing passage 3 of the head of this tool-holder is inserted the tool 4, such as a drill that is oblique in relation to the axis of the tool-holder. According to the invention, this drill is blocked or locked in its position through the upper edge 5 of a first element of fastening 6, consisting of a threaded cone sleeve screwed on the fore part of the tool-holder, this first element being itself immobilized by screwing on its rear part through a second element or sleeve 7, equally screwed on the tool-holder in the same way as the single socket of the principal patent. 
     The sleeve socket 7 blocks the element 6 precluding its unscrewing in the same way as happens to a lock nut against a lock nut. Nut 2T prevents the element 6 from moving axially away from the drill 4 by uncoupling it from the vibrating tool-holder 1; here is the aim of this invention. 
     Of course the first element 6 could be conical as well as cylindrical, fitted through friction or screwing on the head of the tool-holder.