Abstract: A boring tool comprising a tool head provided with a slot extending transverse to the axis of the tool head in which a pair of opposite cutting knives are guided movable in longitudinal direction of the slot. A spacer is guided in the tool head movable between a first and a second position. In the first position the spacer is located between inner ends of the cutting knives which are spring biased to engage the spacer to be movable with the latter in the longitudinal direction of the slot while holding the cutting knives in a cutting position. In the second position the spacer frees the cutting knives to move under the influence of the biasing springs toward each other to an inactive position.

Abstract: The present boring head is constructed for drilling or boring deep holes or bores of substantial axial length whereby so-called veering off from the longitudinal boring axis is to be prevented. For this purpose three cutting members are distributed about the circumference of a base in such a manner that the cutting members are located at 0.degree., 95.degree., and 190.degree. with a position tolerance of .+-.5.degree. for each cutting member relative to a polar coordinate system. At least one guide rod is arranged at an angle of 55.degree. and another guide rod is located at an angle of 305.degree.. Each guide rod position may have a tolerance of .+-.10.degree. in said polar coordinate system.

Abstract: A floating knife of a boring tool for machining the inner surfaces of cylinders, has a cutter member and a support element arranged on both sides of the floating knife. The support elements are arranged for cooperation with the respective cutter member. The support elements are arranged behind the cutter member as viewed in the feed advance direction. The support surface of the support element is spaced behind the cutter member in the floating direction of the floating knife by a spacing corresponding to the extent of the allowable yielding of the cutter member in the radial direction, whereby the cutter member is able to machine the inner surface of a cylinder even if the latter has cross-apertures in its wall because the support member limits the radial floating of the knife to a safe extent.

Abstract: A boring tool having a tool head rotatable about its axis and movable in direction of the axis along a working stroke and a return stroke. A knife having a pair of opposite cutting edges is floatingly mounted in a slot of the tool head extending transverse to the axis thereof and tiltable in the slot between a working position and a withdrawal position in which the cutting edges of the knife project a smaller distance beyond the periphery of the tool head than in the working position to prevent damage of the machined surface during the return stroke of the tool head.

Abstract: A method for finish rolling workpieces of substantially circular cross-section to a selected diameter, in which the workpiece is engaged at circumferentially spaced portions by two rolls, at least one of which is driven for rotation about its axis, and in which at least one of the rolls is moved towards the other, until the portions of the rolls engaging the workpiece have reached a predetermined distance from each other in accordance with the selected diameter of the workpiece, and in which reaching of the predetermined distance is determined by measuring the distance of the peripheral surfaces of the rolls at selected points spaced from the portions thereof engaging the workpiece, and an apparatus for carrying out the method.