A hydraulic chuck device includes a cylinder portion operated by pressure oil, a chuck opened and closed by operation of the cylinder portion, a pressure oil supply controlling pressure of pressure oil supplied to the cylinder portion, and a chuck controller controlling the pressure oil supply. When controlling the pressure oil supply to cause a jaw portion to perform a clamping operation, during movement of the jaw portion from an unclamping position to a preliminary position situated before a clamping position, the chuck controller supplies pressure oil set at a first pressure into a cylinder chamber for clamping to move the jaw portion quickly, and during movement of the jaw portion from the preliminary position to the clamping positon, the chuck controller supplies pressure oil set at a second pressure lower than the first pressure into the cylinder chamber for clamping to move the jaw portion slowly.

Methods and devices for controlling a mechanical joining or forming process, in particular friction drilling in thin-walled materials, apply several reverse pulses acting on a process parameter to bring the course of an actual curve of the parameter more into line with the course of a predetermined nominal curve of the process parameter. The number and length of the reverse pulses and the length of the intervals between the pulses are determined as a function of at least one immediately detectable variable associated with the process parameter.

Methods and devices for controlling a mechanical joining or forming process, in particular friction drilling in thin-walled materials, apply several reverse pulses acting on a process parameter to bring the course of an actual curve of the parameter more into line with the course of a predetermined nominal curve of the process parameter. The number and length of the reverse pulses and the length of the intervals between the pulses are determined as a function of at least one immediately detectable variable associated with the process parameter.

A counter bearing for machining spindles of machine tools has at least one expansion bushing with an elastically deformable wall that delimits at least one pressure chamber. The pressure chamber accommodates a pressure medium. A supply line for the pressure medium opens into the pressure chamber. A pressure conduit opens into the pressure chamber. A mechanically actuatable pressure element is disposed in the pressure conduit and actuated by an actuating tool. A piston is slidably arranged in the pressure conduit and actuated by the pressure element, wherein the piston loads the pressure medium.

A machining apparatus capable of drilling a long workpiece from an end surface of a diameter-expanded part and drilling a short workpiece from an end surface of a stem part without inverting orientation of a collet and a sleeve in a chuck device is provided, as well as a method of using the same, and a chuck device for the machining apparatus. A deep hole drilling machine and a chuck device are included with a sleeve and a collet included inside the chuck device, and the collet and the sleeve each have both end openings opened toward the outside of the chuck device. The opening on one end side of each of the sleeve and the collet is directed to the deep hole drilling machine, and the collet is disposed on the other end side of the sleeve.

A hydraulic chuck device includes a cylinder portion operated by pressure oil, a chuck opened and closed by operation of the cylinder portion, a pressure oil supply controlling pressure of pressure oil supplied to the cylinder portion, and a chuck controller controlling the pressure oil supply. When controlling the pressure oil supply to cause a jaw portion to perform a clamping operation, during movement of the jaw portion from an unclamping position to a preliminary position situated before a clamping position, the chuck controller supplies pressure oil set at a first pressure into a cylinder chamber for clamping to move the jaw portion quickly, and during movement of the jaw portion from the preliminary position to the clamping positon, the chuck controller supplies pressure oil set at a second pressure lower than the first pressure into the cylinder chamber for clamping to move the jaw portion slowly.

A machining apparatus capable of drilling a long workpiece from an end surface of a diameter-expanded part and drilling a short workpiece from an end surface of a stem part without inverting orientation of a collet and a sleeve in a chuck device is provided, as well as a method of using the same, and a chuck device for the machining apparatus. A deep hole drilling machine and a chuck device are included with a sleeve and a collet included inside the chuck device, and the collet and the sleeve each have both end openings opened toward the outside of the chuck device. The opening on one end side of each of the sleeve and the collet is directed to the deep hole drilling machine, and the collet is disposed on the other end side of the sleeve.

A machine control system for a multi-spindle machine includes a controller (42, 86). The controller is operative to reduce the risk of potentially damaging machining chip formation by controlled disengagement of a low speed clutch (18) of a transmission (14) which drives spindles (36) which rotate work pieces. Automatically selectively varying timing and duration of periods of disengagement of the low speed clutch breaks the continuity of chips to reduce the risk of developing damaging conditions as a result thereof.

A counter bearing for machining spindles of machine tools has at least one expansion bushing with an elastically deformable wall that delimits at least one pressure chamber. The pressure chamber accommodates a pressure medium. A supply line for the pressure medium opens into the pressure chamber. A pressure conduit opens into the pressure chamber. A mechanically actuatable pressure element is disposed in the pressure conduit and actuated by an actuating tool. A piston is slidably arranged in the pressure conduit and actuated by the pressure element, wherein the piston loads the pressure medium.

A collet adaptor (10) including a body (11, 12) having forward and rear ends and an axial bore (17) extending through the forward and rear ends. A drawbar (13) disposed at least partly within the bore (17) for connection to a collet (14). The drawbar (13) is secured within the bore (17) and a biasing arrangement (42) acts on the drawbar (13) in a direction tending to shift the drawbar (13) rearwardly within the bore (17). The drawbar (13) is displaceable within the bore (17) against the biasing influence of the biasing arrangement (42) to shift forwardly within the bore (17).