A device for securing a boring device to a boring grate provided with a plurality of positioning bores , said securing device comprising: - a body ; - first means for securing said body to said boring device ; - second means for securing said body to said boring grate , said second securing means comprising an expandable hub, said expandable hub comprising: - an expandable ring traversed by a conical bore formed along a longitudinal axis of said expandable ring ; - an expansion cone housed inside said conical bore of said expandable ring and whose outer peripheral contour is complementary to said conical bore , - means for translating said expansion cone inside said conical bore along said longitudinal axis between at least: - a release position wherein said cone is moved to the side with the larger diameter of said conical bore of said expandable ring so that the latter is in a released state wherein its outer diameter is smaller than that of said positioning bores so that it can be inserted therein or extracted therefrom; - a locking position wherein said cone is moved to the side with the smaller diameter of said conical bore of said expandable ring so that the latter is in an expanded state wherein its outer diameter is increased so as to maintain said securing device secured to said boring grate by friction of said expandable ring against the internal walls of one of said positioning bores , characterised in that said expandable hub further comprises locking balls each housed in an orifice formed in said expandable ring , said expansion cone acting on said locking balls to place them in: - an unblocking position, taken when said cone is in its release position, wherein they do not protrude from the outer peripheral surface of said expandable ring ; - a blocking position, taken when said cone is in its locking position, wherein they protrude from the outer peripheral surface of said expandable ring so as to be able to be housed in a peripheral blocking housing secured to said positioning bores . - a body ; - first means for securing said body to said boring device ; - second means for securing said body to said boring grate , said second securing means comprising an expandable hub, said expandable hub comprising: - an expandable ring traversed by a conical bore formed along a longitudinal axis of said expandable ring ; - an expansion cone housed inside said conical bore of said expandable ring and whose outer peripheral contour is complementary to said conical bore , - means for translating said expansion cone inside said conical bore along said longitudinal axis between at least: - a release position wherein said cone is moved to the side with the larger diameter of said conical bore of said expandable ring so that the latter is in a released state wherein its outer diameter is smaller than that of said positioning bores so that it can be inserted therein or extracted therefrom; - a locking position wherein said cone is moved to the side with the smaller diameter of said conical bore of said expandable ring so that the latter is in an expanded state wherein its outer diameter is increased so as to maintain said securing device secured to said boring grate by friction of said expandable ring against the internal walls of one of said positioning bores , - an unblocking position, taken when said cone is in its release position, wherein they do not protrude from the outer peripheral surface of said expandable ring ; - a blocking position, taken when said cone is in its locking position, wherein they protrude from the outer peripheral surface of said expandable ring so as to be able to be housed in a peripheral blocking housing secured to said positioning bores . <EOS>